First Fall 2023 CM 2100 -Final Exam Study Guide Module 1-7

1. The construction and operation of buildings only accounts for a small amount of the world’s energy consumption and carbon dioxide emissions. FALSE 2. Building construction and operation contribute to many forms of environmental degradation and place a significant burden on the earth’s resources. TRUE 3. Sprawling buildings tend to consume prime agricultural land and degrade natural ecosystems. TRUE 4. The construction and operation of buildings does not affect the quality of the air but does pollute water and soil. FALSE 5. The definition of sustainability has expanded to address the human health impacts of buildings and to include issues of social and economic fairness. TRUE 6. Though ideal, it’s impossible to design a sustainable building that consumes no energy or even generates excess energy, causes no air pollution or even helps clean the atmosphere, and so on. FALSE 7. Sustainable building performance continues to improve while the premium in cost and effort to design and construct such buildings continue to rise as well. FALSE 8. Reducing reliance on electrical lighting also reduces excess heat generated from electrical lighting which allows the building’s cooling system to be reduced in capacity and physical size. TRUE 9. The Green Building Council provides sustainability ratings to new buildings as well as already existing ones. TRUE 10. The highest goal of The International Living Future Institute’s Living Building Challenge is the aspiration to designs buildings that do less environmental harm. FALSE 11. Designing sustainable buildings requires access to information about the environmental and health impacts of the materials used in their construction. TRUE 12. Information about building materials and products come from a single standardized source. FALSE 13. Information about building materials and products may be self-reported by the product manufacturer, or it may come from an independent, trusted third party. TRUE. 14. The scope of information provided on a Product Data Sheet (PDS) is left entirely to the manufacturer, and the information is not independently verified. TRUE 15. Environmental labels, also called ecolabels, are third-party environmental ratings. TRUE 16. Product disclosures and ecolabels always rate the sustainability of a product in a standardized format for easy comparison of alternative materials or products. FALSE 17. Environmental Product Declarations (EPDs) describe the full, life-cycle environmental impacts of building materials and products. TRUE

54. A design/build project begins when the owner developing a conceptual design or program that describes the functional or performance requirements of the proposed facility including detail of its form and how it is to be constructed. FALSE 55. Design/build project delivery gives the owner a single source of accountability for all aspects of the project. TRUE 56. As in design/build construction, the construction manager participates in the project prior to the onset of construction, introducing construction expertise during the design stage. TRUE 57.In turnkey construction, an owner contracts with multiple entities that provide the design, construction services, and financing for the project as well. FALSE 58. A single-purpose entity consists of the owner, architect, and contractor as joint members. TRUE 59. Means of egress describes how far back a building sits from the road. FALSE 60. Swimming pools are regulated by health codes that also govern food-service operations, schools, and healthcare facilities. TRUE 61. Fixed-fee, or lump-sum, compensation means the general contractor or other construction entity is paid at the end of the project after the actual cost of the project is once. FALSE 62. Cost plus a fee compensation means the owner pays the construction entity for the actual cost of construction—whatever that may turn out to be—plus an additional amount to account for overhead and profit. TRUE 63. Guaranteed maximum price (GMAX or GMP) compensation describes the maximum fee the owner may be required to pay. Until reaching that maximum, the compensation is handled as regular cost plus a fee. TRUE 64. Incentive provisions are set through agreements between owner and contractor to reward a contractor for timely and professional attitude throughout the project. FALSE 65. Surety bonds are bought from third party to protect the owner from the risks of default by the construction contractor—a performance bond assures the completion of the construction, and a payment bond assures full payment to suppliers and subcontractors. TRUE 67. In sequential construction, each major phase in the design and construction of a building is completed before the next phase begins, and construction does not start until all design work has been completed. TRUE 68. In phased construction, or fast track construction, each major phase in the design and construction of a building is completed before the next phase begins, and construction does not start until all design work has been completed. FALSE 69. A Gantt chart consists of a series of horizontal bars used to represent the various teams working on different parts of a project, providing an easy-to-understand representation of construction tasks and who is in responsible for it. FALSE 70. The critical path of a project is the sequence of activities that determines the least amount of time in which a project can be completed. TRUE 71. The critical path method (CPM) is a technique for optimizing the deployment of the right number of people to work on a certain task in order to fulfill the project’s critical path. FALSE

Construction Specifications Institute (CSI): MasterFormat  Outline for Construction Specifications  Numbering system for the organization of construction materials and systems  Developed by CSI and Canadian counterpart Construction Specifications Canada (CSC)  50 major Divisions  Often used by Contractors for Construction Cost Coding Divisions are subdivided in Sections, that define the work of individual trades or suppliers. Sections may be further subdivided if needed. Division 05 – Metals  Section 05 10 00 – Structural Steel Framing  Section 05 21 00 – Steel Joist Framing  Section 05 31 00 – Steel Decking  Section 05 40 00 – Cold-Formed Metal Framing  Section 05 50 00 – Metal Fabrications o Section 05 51 33 – Metal Ladders  Section 05 51 33.13 Vertical Metal Ladders The Work of the Construction Professional: Constructing Buildings Providing Construction Services  Owner- a finished project that meets its functional requirements & its expectations for design and quality at the lowers possible cost and on a predictable schedule.  Contractor- quality work, earn a profit, & complete the project in a timely fashion.  Building process is fraught with uncertainties o Variable workforce, material prices, & weather  Owner-Contractor relationship- must be structured to share the rewards & risks. Construction Project Delivery Methods Design/Bid/Build  Owner separately hires design team and construction team  Advantage: Separate design and construction entities provide useful checks and balances  Disadvantage: Difficult to integrate construction expertise into design Design/Build  Owner hires one entity that provides both design and construction services  Advantage: Allows fuller collaboration between design and construction teams  Disadvantage: Lack of independent advocate for design; fewer built in checks and balances Construction Management  Owner hires CM as independent entity to oversee design and construction services provided by multiple entities  Advantage: Independent construction expertise is available to owner throughout project  Most commonly associated with large scale, complex projects Other project delivery forms:  CM at risk : combines aspects of construction manager with general contractor.  Turnkey construction entity : provides financing as well as construction services  Single-purpose entity : combines owner, design, and construction teams into one legal entity and many more variations Sequential vs. Fast Track Construction Sequential Construction  Each major project phase begins only after the preceding phase is completed  Design is completed before construction begins Phased /Fast Track Construction  Design and construction phases overlap

Caisson, drilled pier: A cylindrical sitecast concrete foundation unit that penetrates through incompetent soil to rest upon an underlying stratum of rock or satisfactory soil; an enclosure that permits excavation work to be carried out underwater. Also called a drilled pier. Pile: A long, slender piece of material driven into the ground to act as an element of a foundation. Pile cap: A thick slab of reinforced concrete poured across the top of a pile cluster to cause the cluster to act as a unit in supporting a column or grade beam. Grade beam: A reinforced concrete foundation element that transmits the load from a bearing wall into spaced foundations such as pile caps or caissons. Piledriver: A machine for driving piles. Heaving: The forcing upward of ground or buildings by the action of frost or pile driving. Base isolator: A device at foundation level that diminishes the transmission of seismic motions to a building. Underpinning: The process of placing new foundations beneath an existing Structure. Up-down construction: A sequence of construction activity in which construction proceeds downward on the sublevels of a building at the same time as it proceeds upward on the superstructure. Guided Reading Questions Answers 1. Dead load is the combined weight of all wasted materials accumulated throughout the construction process. FALSE 2. Live loads are nonpermanent loads caused by the weights of the building’s occupants, furnishings, and movable equipment. TRUE 3. Rain and snow loads act primarily downward on a building, while wind loads act laterally(sideways). FALSE 4. Buoyant uplift forces caused by underground water are identical to the forces that cause a boat to float. TRUE 5.Horizontal thrust forces come from long-span structural components, such as arches, rigid frames, domes, vaults, or tensile structures. TRUE 6. Dead and live load, heavy and light loads, rain and snow loads, wind loads, seismic loads, lift and drag load, and lateral soil pressure loads are all examples of various loads that can act on a building. FALSE 7. A well-constructed building will not experience settling of its foundation. FALSE 8. Earth materials are classified according to particle size, the presence of organic content, and, in the case of finer0grained soils, sensitivity to moisture content. TRUE 9.Consolidated rock, or bedrock, is a dense, continuous mass of mineral material that cannot be mined through. FALSE 10. Natural rock often occurs as monolithic and unvarying in composition or structure. FALSE 11. Bedrock is generally the strongest and most stable material on which a building can be founded. TRUE 12. Soil is a general term referring to any earth material that is a particulate. TRUE 13. Gravel and sand are collectively referred to as fine-grained soils. FALSE

44. An example of ground improvement is to remediate biologically or chemically contaminated soil by adding chemicals that neutralize the contamination. TRUE 45. A slurry wall is a coating of quick drying cement sprayed over loose ground to prevent runoff. FALSE 46. A clamshell bucket is used in the excavation for a slurry wall, operated by a crane. TRUE 47. A slurry is a viscous mixture of water and bentonite clay or polymers used to exert pressure against the earthen walls during a deep excavation. TRUE 48. Contiguous pier excavation support consists of cylindrical concrete piers spaced widely apart and formed with steel reinforcing. FALSE 49. When contiguous piers are spaced so that their edges encircle the perimeter of the construction site, it’s called a tangent wall. FALSE 50. Rakers and crosslot bracing make the excavation process easier by decreasing the limitations on earth removal methods and equipment. FALSE 51. Excavation in fractured rock must always be done with sheeting to stabilize the blocks. FALSE 52. Soil nailing involves a length of steel bar inserted into a nearly horizontal hole drilled deep into the soil and injected with grout to bind the bar (or nail) to the surrounding soil. TRUE 53. The function of bracing and tiebacks in excavations is eventually taken over by the floor structure of the basement levels of a building, which is designed to resist lateral loads from the surrounding earth acting on the substructure walls. TRUE 54. Most excavations require some form of dewatering, or removal of water from the excavation or surrounding soil. TRUE 55. Low points in the excavation, where water tends to accumulate, are called sumps. TRUE 56. Well points are used to depress the water table, made of vertical pipes inserted into the ground with screened openings at the bottom that keep out soil particles. TRUE 57. Soil freezing is when an array of vertical pipes is used to freeze water in excavation tunnels to help support the earthen walls. FALSE 58. Shallow foundations transfer building loads to the earth close to the base of the structure. TRUE

85. In areas where very strong earthquakes are common, very large buildings may be protected from the strong lateral forces by means of base isolators. TRUE 86. Underpinning is the strengthening and stabilizing of an existing foundation. TRUE 87. Where building substructures enclose basements, parking garages, or other useable spaces, substantial concrete barriers are used to keep groundwater out. FALSE 88. Waterproofing and dampproofing are similar methods of protecting enclosed substructures from water entry from very wet soils or when foundations are submerged below the surrounding water table. FALSE 89. Integral waterproofing is added to wet concrete mixture to plug up small pores and microcracks in hardened concrete, making the concrete itself more watertight. TRUE 90. Waterstops made of plastic, synthetic rubber, metal, or other materials can be cast into joints that occur in foundation construction between separate concrete pours to block the passage of water through these especially vulnerable locations. TRUE 91. Horizontal membranes are used to guard against future foundational leaks and must be tested and inspected on its ability to keep all groundwater out of the soil beneath the building. FALSE 92. One method for testing the integrity of a horizontal membrane is flood testing, in which a building is pumped full of water overnight and then checked for leaks. FALSE 93. Concrete slab on grade foundations do not require insulation when sufficiently far below grade. TRUE 94. Radon is a cancer-causing gas that occurs naturally within soils and whose prevalence varies by region and locality. TRUE 95. Passive radon control is used to minimize gas infiltration into a building with certain air conditioner filters certified for this use by ASTM and other independent organizations. FALSE 96. Gabions are a form of earth retention in which corrosion resistant wire baskets are filled with plastic bags and then stacked for form retaining walls and slope protection. FALSE 97. Each lift of replacement soil may range from four inches to roughly a foot deep and compacted before the next lift is added. TRUE

 Weekly Readings  Chapter 13 - Concrete Construction o Key Terms o Guided Reading Questions o Why concrete is such important material? o Concrete Properties o Cement and Concrete o Making and Placing Concrete o Reinforcing o Prestressing o Additional Resources  Chapter 14 - Site Cast Concrete o Key Terms o Guided Reading Questions o Concrete Construction - Options o Casting on a Concrete Slab on Grade o Casting a Concrete Wall o Casting a Concrete Column o Elevated Framing Systems o One-Way Floor and Roof Framing Systems o Two-Way Floor and Roof Framing Systems o Site Cast Post-tensioning Systems o Additional Resources  Chapter 15 – Precast Construction o Key Terms o Precast Concrete o Precast Prestressed Concrete Structural Elements o Manufacturing of Precast Concrete Structural Elements o Joining Precast Concrete Elements o Precast Elements and Other Structural Materials o Additional Resources Weekly Readings This week you will need to read Chapters 13, 14 and 15 in your textbook. As you are reading, focus on various reinforcement methods within concrete systems, including formwork, beams, columns, prestressed and post stressed members. Chapter 13 - Concrete Construction Thought Points  Focus on difference between cement and concrete and concrete components.  Focus on the process of making and placing concrete.

Key Terms Portland cement : A gray or white powder, composed principally of calcium silicates, which, when combined with water, hydrates to form the binder in concrete, mortar, and stucco. Concrete : A structural material produced by mixing predetermined amounts of cement, aggregates, and water and allowing this mixture to cure under controlled conditions. Aggregate : Inert particles, such as sand, gravel, crushed stone, or expanded minerals, in a concrete, mortar, or plaster. Coarse aggregate : Gravel or crushed stone in a concrete mix. fine aggregate Fine aggregate : Sand used in concrete, mortar, or plaster mixes. Curing : The hardening of concrete, plaster, gunnable sealant, or other wet materials. It can occur through evaporation of water or a solvent, hydration, polymerization, or chemical reactions of various types, depending on the formulation of the material. Hydration : The process by which cements combine chemically with water to harden. Heat of hydration : The thermal energy given off by concrete or gypsum as it cures. Drying shrinkage : Shrinkage of concrete, mortar, or plaster that occurs as excess water evaporates from the material. Clinker : A fused, pebble-like mass that is an intermediate product of cement manufacture; a brick that is over-burned. Air-Entraining Cement : Ingredients added generate bubbles during concrete mixing that create small, distributed voids in the finished concrete. White portland cement : A portland cement that is white in color; used for architectural concrete where greater color control is required. High-volume fly ash concrete (HVFA concrete) : A concrete in which a high percentage of cementing substance is sly ash rather than portland cement. Lightweight aggregate : Low-density aggregate used to make lightweight concrete, mortar, and plaster; in concrete, aggregate with a density of less than 70 lb/ fo (1120 kg/mo). Structural lightweight aggregate : Lightweight aggregate with sufficient density and strength for use in structural concrete. Expanded shale aggregate : A structural lightweight aggregate made from ground shale particles that have been heated to the point that moisture within the particles vaporizes, causing the particles to expand. Vermiculite : Expanded mica, used as an insulating fill or lightweight aggregate. Perlite : Expanded volcanic glass, used as a lightweight aggregate in concrete and plaster and as an insulating fill. Water—cement ratio : An expression of the relative proportions, by weight, of water and cement in a concrete mixture. Supplementary cementitious material (SCM) : Hydraulic cementitious material or pozzolan mixed with portland cement to modify the cement product's properties or lower the energy required to manufacture the cement. Pozzolan : A supplementary cementitious material, such as fly ash, silica fume, and some naturally occurring shales and clays, that has few or no inherent cementitious properties but that, in the presence of moisture, can react with calcium hydroxide released by other cementitious materials to create a hydraulic cement product. The Romans mixed natural pozzolans with lime to make the first hydraulic cement. Fly ash : Dust collected in the stacks of coal-fired power plants, used as a supplementary cementitious material in concrete and mortar. Silica fume : Very finely divided silicon dioxide, a pozzolan, used as an admixture in the formulation of high-strength, low-permeability concrete; also called microsilica. High-reactivity metakaolin : A whitecolored natural pozzolan that enhances appearance, workability, and hardened properties of concrete. Blast furnace slag : A hydraulic cementitious material formed as a byproduct of iron manufacture, used in mortar and concrete mixtures, also called slag cement. Hydraulic cements : Cementitious materials, such as portland cement or blast furnace slag, that harden by reacting with water and whose hardened products are not water soluble. Blended hydraulic cement : Hydraulic cement made from a mixture of cementitious materials such as portland cement, other hydraulic cements, and pozzolans for the purpose of altering one or more properties of the cement or reducing the energy required in the cement manufacturing process. Admixture : In a concrete or mortar, a substance other than cementitious material, water, and aggregates included in the mixture for the purpose of altering one or more properties of the mixed material, either in its plastic working state or after it has hardened. Air-entraining admixture : An admixture that causes a controlled quantity of stable microscopic air bubbles to form in concrete or mortar during mixing, usually for the purposes of increasing workability and resistance to freeze- thaw conditions. Water-reducing admixture : Concrete admixture that allows a reduction in the amount of mixing water while retaining the same workability, resulting in higher strength concrete. High-range water-reducing admixture, Superplasticizer : An admixture that makes wet concrete or grout extremely fluid without additional water. Accelerating admixture : An admixture that causes concrete or mortar to cure more rapidly. Retarding admixture : An admixture used to slow the curing of concrete, mortar, or plaster. Workability agent : Admixture for concrete that improves the plasticity of wet material to make it easier to place in forms and to finish. Shrinkage-reducing admixture : A concrete additive that reduces drying shrinkage and the cracking that results. Corrosion inhibitor : A concrete, mortar, or plaster admixture intended to prevent oxidation of steel reinforcing bars. Freeze protection admixture : A concrete or mortar additive, used to allow curing under conditions of low ambient temperature. Extended set-control admixture : A substance that retards the onset of the curing reaction in concrete so that the material may be used over a protracted period of time after mixing. Water-cement ratio, w-c ratio : An expression of the relative proportions, by weight, of water and cement in a concrete mixture. Transit-mixed concrete : Concrete mixed in a drum on the back of a truck as it is transported to the building site.

Slump test : A test in which wet concrete or plaster is placed in a cone-shaped metal mold of specified dimensions and allowed to sag under its own weight after the cone is removed. The vertical distance between the height of the mold and the height of the slumped mixture is an index of the material's working consistency. Slurry : A watery mixture of insoluble materials with a high concentration of suspended solids . Segregation : Separation of the constituents of wet concrete caused by excessive handling or vibration. Dropchute : A flexible hose-like tube for placing concrete; used to break the fall of the concrete and prevent segregation. Consolidate : In freshly poured concrete, to eliminate trapped air and cause the concrete to fill completely around the reinforcing bars and into all the corners of the formwork; usually done by vibrating the concrete. Self-consolidating concrete (SCC) : Concrete formulated so that it is highly flowable and fills formwork completely without needing consolidation. Formwork : Structures, usually temporary, that give shape to poured concrete and support it and keep it moist as it cures. Form release compound : A substance applied to concrete formwork to prevent concrete from adhering. Precast concrete : Concrete cast and cured in a location other than its final position in the structure. Sitecast concrete : Concrete that is poured and cured in its final position in a building; cast in place concrete. Reinforced concrete : Concrete work into which steel bars have been embedded to impart tensile strength to the construction. Steel reinforcing bars : Hot-rolled, deformed steel bars used to impart tensile strength and ductility to concrete or masonry structures; rebar. Deformed reinforcing bar : Steel reinforcing bars with surface ribs for better bonding to concrete. Welded wire reinforcing (WWR) : A welded grid of steel reinforcing wires or bars, used most commonly for reinforcing of slabs; also called welded wire fabric (WWF). Bottom bar : A reinforcing bar that lies close to the bottom of a beam or slab. Cover : In concrete, a specified thickness of concrete surrounding reinforcing bars to provide full embedment for the bars and protect them against fire and corrosion. Bond : In masonry, the adhesive force between mortar and masonry units, or the pattern in which masonry units are laid to tie two or more wythes together into a structural unit. In reinforced concrete, the adhesion between the surface of a reinforcing bar and the surrounding concrete. Hook : A semicircular bend in the end of a reinforcing bar, made for the purpose of anchoring the end of the bar securely into the surrounding concrete. Stirrup : A vertical loop of steel bar used to reinforce a concrete beam against diagonal tension forces. U-stirrup : An open-top, U-shaped loop of steel bar used as reinforcing against diagonal tension in a concrete beam. Stirrup-tie : A stirrup that forms a complete loop, as differentiated from a U-stirrup, which has an open top. Chair : A device used to support reinforcing bars. Bolster : A long chair used to support reinforcing bars in a concrete slab. One-way action : The structural action of a slab that spans between two parallel beams or bearing walls. Shrinkage temperature steel : Reinforcing bars laid at right angles to the principal bars in a oneway slab for the purpose of preventing excessive cracking caused by drying shrinkage or temperature stresses in the concrete. Two-way action : Bending of a slab or deck in which bending stresses are approximately equal in the two principal directions of the structure. Vertical bar : An upright reinforcing bar in a concrete column; also called a column bar . Tie : A device for holding two parts of a construction together; a structural device that acts in tension. Column spiral : A continuous coil of steel reinforcing used to tie a concrete column. Column tie : A single loop of steel bar, usually bent into a rectangular configuration, used to tie a concrete column. Fibrous reinforcing : Short fibers of glass, steel, or polypropylene mixed into concrete to act as either microfiber reinforcing or macrofiber reinforcing. Microfiber reinforcing : In concrete, fibrous reinforcement against plastic shrinkage cracking. See also Macrofiber reinforcing. Macrofiber reinforcing : In concrete, fibrous reinforcement capable of providing resistance to drying shrinkage and thermal stresses, and in some specialized concretes, also capable of acting as primary reinforcing. See also Microfiber reinforcing. Plastic shrinkage cracking : Cracking in freshly mixed concrete, most commonly in slabs, that occurs when the surface of the concrete dries too rapidly. Creep : A permanent inelastic deformation in a material due to changes in the material caused by the prolonged application of a structural stress; common in wood, concrete, and plastics. Prestressing : Applying an initial compressive stress to a concrete structural member, either by pretensioning or postlemsioning. Prestressed concrete : Concrete that has been pretensioned or posttensioned. Pretensioning : Compressing the concrete in a structural member by pouring the concrete for the member around stretched high-strength steel strands, curing the concrete, and releasing the extermal tensioning force on the strands. Camber : A slight, intentional curvature in a beam or slab. Posttensioning : Compressing the concrete in a structural member by tensioning high-strength steel tendons against it after the concrete has cured. Tendon : A steel strand used for pre-stressing a concrete member. Draped tendon : A posttensioning strand placed along a curving profile that approximates the path of the tensile forces in a beam. Pervious concrete: Concrete with a high percentage of void space, used as a paving material that allows stormwater to pass through.

Guided Reading Questions Guided Reading Questions Answers 1. The Romans were the inventors of concrete construction. TRUE 2. The mortar the Romans discovered was weaker when it hardened underwater. FALSE 3. Reinforced concrete is concrete embedded with steel bars that resist tensile forces. TRUE 4. The name “portland,” for the cementitious component of concrete remains in use today. TRUE 5. Concrete is a rocklike material produced by mixing coarse and fine aggregates, portland cement, and water and allowing the mixture to harden. TRUE 6. Fine aggregate is normally gravel or crushed stone, and coarse aggregate is sand. FALSE 7. Type 1 cement is used for most purposes in construction. TRUE 8. Fly ash, also known as microsilica, is a powder that is approximately 100 times finer than portland cement, consisting mostly of silicon dioxide. FALSE 9. Large batches of concrete in North America are not mixed until they reach the job site. FALSE 10. Freshly mixed concrete is a liquid. FALSE 11. Segregation is prevented by depositing the concrete, fresh from the mixer, as close to its final position as possible. TRUE 12. Once placed, concrete must be consolidated to eliminate trapped air and to completely fill the space around the reinforcing bars and in all corners of the formwork. TRUE 13. Form release compounds are an oil, wax, or plastic that prevents adhesion of the concrete to the form. TRUE 14. Precasting is a process in which concrete is cast in single use forms at an industrial plant. FALSE 15. Reinforcing bars in concrete structures that are exposed to salts, such as deicing salts or those in seawater, are prone to rust. TRUE 16. Steel reinforcing bars (rebar) are square in cross section. FALSE 17. Steel reinforcing bars (rebar) are deformed with surface ribs that help strengthen the bond between the bars and the concrete in which they are cast. TRUE 18. Increasing bar sizes and decreasing the spacing between the bars reduces rebar congestion. FALSE 19. As an alternative to conventional reinforcing bars, reinforcing is also produced in sheets or rolls of welded wire. TRUE 20. In an ideal, simply supported beam under uniform loading, compressive (squeezing) forces follow a set of archlike curves that create a maximum stress in the top of the beam at midspan, with progressively lower compressive stresses toward either end. TRUE 21. When placed under sustained compressive stress from its own weight, the weight of other permanent building components, or the force of prestressing, concrete will gradually and permanently shorten over a period of months or years. This is called shrink. FALSE 22. Pretensioning is done almost exclusively in place on the building site. FALSE

23. The net effect of posttensioning is the same as that of pretensioning. TRUE 24. Pretensioning is useful only for concrete members cast in precasting plants. TRUE 25. Among the major structural materials, concrete is unique in that the largest share of it is manufactured in-place on the construction site rather than in a factory. TRUE 26. Of all the major structural building materials, concrete seems the least subject to continual innovation in its formulation and capabilities. FALSE 27. Engineered cementitious composites (ECCs) are precisely tailored mixtures of polymer fiber-reinforcing, cementitious materials, and fine aggregate that produce concretes with higher tensile strength and ductility. TRUE 28. Engineered cementitious composites (ECCs) exhibit stress–strain behavior unlike ductile metals, resulting in materials with decreased durability under flexural and seismic loads. FALSE 29. The hardening of concrete is called curing. TRUE 30. During the curing process of concrete, considerable heat, called heat of hydration, is given off. TRUE 31. Air-entraining cements contain ingredients that cause microscopic air bubbles to form in the concrete during mixing. TRUE 32. When a concrete building is demolished, its reinforcing steel cannot be recycled. FALSE 33. The strength of a concrete is not dependent on the quality of its aggregates. FALSE 34. Pozzolans are materials that react with the calcium hydroxide in wet concrete to form cementing compounds. TRUE 35. Silica fume is not considered a Pozzolan. FALSE Why concrete is such important material?  Universal material of construction  Readily available- globally  Good properties- does not rot or burn  Relatively low cost  Can be use for every building purpose Concrete Properties  Versatile  Pliable when mixed  Strong & Durable  Does not Rust or Rot  Does Not Need a Coating  Resists Fire

Cement and Concrete Concrete Ingredients  Fine aggregate (sand)  Coarse aggregate (gravel) o Coarse and fine aggregate provide the structural mass of the concrete and constitute the majority of the concrete volume.  Portland cement (Calcium silicates) o Cement binds the aggregate.  Water o Water is necessary for the chemical hydration of the cement and the hardening of the concrete. Portland Cement  Generic Term  Man Made Product  Fine gray powder  Glue (Binder)  Curing - Hydration (a chemical process) Air-Entraining Cement  Ingredients added generate bubbles during concrete mixing that create small, distributed voids in the finished concrete.  Greater resistance to freeze-thaw damage .  Air-entrained concrete also has improved workability when wet.  Air entraining reduces concrete strength , unless the proportions of other ingredients in the concrete mix are adjusted to compensate. ASTM C150 Cement Types  Type I: General purpose  Types II and Type V: For concrete in contact with soils or water with high sulfate concentrations  Type III: For cold weather construction, concrete precast in plants, accelerated construction schedules  Type IV: For massive structures, such as dams, where the heat generated during hydration must be limited to avoid excessive temperatures Aggregates  Coarse and fine aggregate make up 60 to 80% of the total concrete volume.  Most aggregate comes from natural sand and gravel deposits or is made from crushed rock.  Artificial aggregates may come from: o Blast furnace slag o Fly ash o Recycled concrete o Thermally treated clay, shale, and other minerals Aggregates- Strength  Strength of concrete is heavily dependent on the quality of the aggregates: o Porosity o Size distribution o Moisture absorption o Shape and surface texture o Strength, elasticity, density, soundness o Contamination or detrimental substances Aggregate Size Distribution

 Grading: Distribution of aggregate particle sizes  Generally, a lower percentage of void space between particles results in a stronger concrete that requires less cement.  To reduce void volume, a graded range of aggregates varying in size is used.  Aggregate grading also affects workability of wet concrete. Lightweight Aggregates: Used to make lighter-weight concrete  Structural lightweight concrete: o Roughly 80 percent or less of the weight of ordinary concrete o Reduced structure weight saves costs o Lower thermal conductivity increases resistance to building fires  Nonstructural lightweight concrete: o Roughly 60 percent or less of the weight of ordinary concrete o Insulating roof toppings o Fill material  Expanded shale, clay, slate, slag  Cinders and other volcanic rocks  Vermiculate

 Perlite Aggregates Must be:  Clean, Strong  Resistant to freeze-thaw  Chemically stable  Properly Graded o mix distribution & o installation space ASTM laboratory tests Admixtures used to alter concrete properties  Air-entraining admixtures  Water-reducing admixtures  High range water-reducers - superplasticizers  Accelerating & retarding admixtures  Fly ash  Workability agents  Fibrous admixtures  Coloring agents E.g., High-strength concrete for very tall buildings:  Supplementary Cementitious Materials, for greater strength  Water reducers, to increase concrete strength while maintaining workability  Admixtures to improve pumpability  Retarding admixtures, to allow adequate time for placing Water  Water is an essential ingredient in concrete, that combines chemically with the cement as the concrete hardens.  Water must be free of contaminants.  The quantity of water in the concrete mix must be controlled as closely as any other ingredient: o Adding unneeded water dilutes the cement paste, weakening the hardened concrete. Effect of Water-Cement Ratio Why strength reduced?  Extra water - evaporates, leaving microscopic voids that impair the strength and surface qualities. Making and Placing Concrete Concrete Mix Design  Science  Establishes Materials & Proportions  A process to establish the desired: o Workability of wet concrete o Physical properties of cured concrete o Acceptable Cost  Coordinated / Approved by Engineer Requirements for Quality Concrete  Proper Selection of Materials

 Correct proportioning, mixing, & material transport  Careful placing and consolidation  Skillful finishing  Adequate curing Concrete Quality  Workability: Ease of placing, consolidating, & finishing wet concrete  Structural properties when hardened: Strength, stiffness, durability  Many other important properties: o Ease of placement o Rate of early strength gain o Degree shrinkage during curing o Flatness, for slabs and paving o Surface hardness, for industrial slabs o Porosity o Density o Surface appearance o Cost o and more… Concrete Strength  Concrete strength varies with design of the concrete mix.  Normal strength concrete o Up to 6000 psi compressive strength o Made with conventional ingredients  High-strength concrete o Greater than 6000 psi to roughly 20,000 psi o Supplementary cementitious materials are required to reach higher strengths. o Lower water content, required for higher strength, results in a stiff, unworkable mixture when wet.  To compensate, water reducing admixtures or high-range water reducing admixtures (superplasticizers) are used to improve workability. Concrete Compressive Strength  Specified by 28 Day Compressive Strength o Measured in pounds of compressive strength per square inch (psi)  Primarily Determined By: o Amount of Cement o Water-Cement Ratio o Other influencing factors:  Admixture(s)  Aggregate Selection & Gradation  Strength Ranges: 2000 - 22,000+ psi Concrete Measurement, Mixing, Transport & Testing  Unit of Measure - Cubic Yard

 Plant Certification  Mixing  Transport (transit mixed- 9 to12 CY)  Slump Test  Test Cylinders  “In Place” Coring, if Required Mixing Concrete  Most concrete is prepared at batch plants and delivered to the construction site in transit-mix (ready mix) trucks.  The concrete ingredients are mixed in the rotating drum of the truck so that the concrete is ready to pour on arrival at the construction site.  Smaller batches of concrete may be prepared on site by hand or with the aid of portable power mixers . Slump Test  The slump test provides a rough measure of the workability of concrete while wet.  Concrete is placed into a conical cylinder; the cylinder is removed, and the loss in height of the concrete mass is measured. o Concrete with too low slump may be difficult to place. o Concrete with too high slump may have had too much water added.  Specified maximum slump is usually in the range of 3 to 5 inches.  Slump tests are performed on batches of concrete as the arrive on the concrete site. Strength Test Cylinders  Test cylinders may be cast from each batch of concrete delivered to the construction site.  Cylinders are returned to the laboratory, cured under controlled conditions, and then strength-tested at appropriate times.  Cylinders can also be cured on site in conditions similar to that for the cast concrete (e.g. remove formwork or subject cast concrete to construction loads) Building Materials Material Tension Compression Wood 700 psi 1,100 psi Brick 0 psi 250 psi Steel 22,000 psi 22,000 psi Concrete 0 psi 2,000 to 22,000+ Placing Concrete  Avoid delays- concrete can stiffen and become difficult to place.  Concrete that does stiffen can have water added prior to placing, provided that: o Maximum w/c ratio is not exceeded o Maximum slump is not exceeded o Agitation limits are not exceeded  Concrete may be placed on site directly from the discharge chute of a transit-mix truck, or by combination of wheelbarrows, power buggies, crane-lifted buckets (right), conveyor belts, pumpers, or other devices.  Segregation, separation of large aggregate from the finer portions of the mix, must be avoided.  Place concrete as close to final position as possible.  Do not push concrete over large horizontal distances.  Avoid dropping concrete from high heights or discharging against obstacles (use drop chutes if needed). Consolidating Concrete  Consolidation- eliminates voids and air pockets within the concrete pour. o Hand rodding or tamping

o Screeding (top) o Internal vibration (bottom) o External vibration  Consolidation is especially critical with stiff concrete mixes or when concrete is placed around densely packed reinforcing arrays .  Over-consolidation must be avoided , as it can lead to segregation of aggregate as larger particles descend and finer components rise to toward the surface. Concrete Segregation  Segregation - Mix “Separates”  Results - Non-uniformity & Unsatisfactory properties  Common Causes: o Excessive Vibration o Dropping From Excessive Heights o Moving Concrete Horizontally Concrete Curing  Hydration- the chemical bonding of water and cement.  Concrete strength is normally specified at 28 days.  Exposed surfaces of newly poured concrete must be protected from evaporation and drying. Methods to Keep Moist  Formwork  Application of H2O  Covering  Curing Compound Curing - Temperature Extremes  Hot Weather o Issues: Premature Drying / Accelerated Curing o Solutions:  Ice Substituted for Water  Early or Late Placement Times  Cold Weather o Issues: Hydration proceeds much slower and Risk of Freezing o Solutions: Blankets (Cover), Temporary Heat Concrete Formwork  Temporary Structure- to hold freshly poured concrete in the desired shape  Protects newly poured concrete from drying too quickly .  Must be designed to support: o Concrete & Reinforcing o Construction Loading o Be easily stripped once concrete is cured  In conventional concrete construction, formwork can account for half or more of total concrete construction costs .  Form release compounds- oils, waxes, or plastic coatings o Applied to formwork surfaces to prevent adhesion of the formwork to the concrete and ease formwork removal.  Quality of the finished concrete surface

o Quality of the form material o Structural Strength (including the form tie and framing spacing) Formwork Materials TYPES:  Wood  Metal  Plastic/Fiberglass  Cardboard Reinforcing Concrete Reinforcing  Concrete has no useful tensile strength—ability to resist pulling forces.  Steel bars or wires are laid into concrete along lines of tension, to provide resistance to these forces.  Steel and concrete work well together. o The two materials have similar rates of thermal expansion/contraction. o The alkaline chemistry of the concrete protects the steel from corrosion. o The two materials bond well, allowing them to work as a single structural composite. Steel Reinforcing Bars  Steel reinforcing bars (rebar): most common concrete reinforcing material .  Hot-rolled steel , deformed with surface ridges so as to better bond with concrete.  Bar sizes are numbered- diameter of the bar in 8ths of an inch. o #4 bar is 1/2 in. diameter o #8 bar is 1 in. diameter  Bars are made with steel grades of varying strength.  Higher strength bars are used to reduce rebar congestion , where reinforcing becomes crowded and concrete placement becomes more difficult. Reinforcing Support  Reinforcing Support o Chairs or bolsters o Properly position the steel Reinforcing Special Coatings  Galvanized or Epoxy Coated  Exposure to Salts or Sea Water Welded Wire Reinforcing  Welded wire reinforcing (WWR) or welded wire fabric (WWF): Prefabricated, welded grids of reinforcing bars or wires  Especially common for concrete slab reinforcing .  Designation example:  6x12-W12xW5 o W12 wires spaced at 6 in., crossed by o W5 wires spaced at 12 in.  Comes in Mats or Rolls  Advantage - Labor Savings Reinforcing Fabrication & Erection  Concrete reinforcing requirements are shown on the structural drawings .

 A reinforcing fabricator prepares shop drawings that are reviewed by the structural engineer.  Reinforcing is cut to length, bent as needed, and possibly partially assembled before being transported to the construction site.  Fabrication continues on site. Eventually reinforcing is assembled in its final configuration.  After inspection by the engineer, concrete may be poured. Reinforcing Installation  Hoist bundles to desired location  Place and Secure (tie)  Splicing Purpose o Transfer Loads  Splicing Methods o Overlap a specified # of bar diameters o End to end; weld or mechanical splice Reinforcing a Simple Beam  In a simply supported beam, the greatest tension forces occur at the bottom middle of the beam.  Where tension forces cross compression forces closer to the beam ends, shear forces also occur.  The placement of reinforcing in a concrete beam approximates the lines of tension , but is simplified to reduce fabrication costs. Reinforcing a Column  Vertical or column bars: Larger-diameter bars placed vertically in the column  Ties or spirals: Wrap around the vertical bars  The vertical bars add to the strength of the column in compression, and resist tensile forces that are introduced from wind or seismic forces, or from connections to beams.  Ties prevent the vertical bars from buckling outward .  Note how, where the vertical bars extend beyond the ties, they are bent slightly inward toward the center of the column. As the column height is extended further, the next section of reinforcing will nest and overlap with these ends . Fibrous Reinforcing  Fibrous reinforcing: Short fibers of glass, steel, or polypropylene, added to the concrete mix  Microfiber reinforcing: Relatively low amounts of fibers, to aid concrete in resisting plastic shrinkage cracking that occurs during early curing  Macrofiber reinforcing: Greater concentrations of fibers, that also resist longer-term cracking due to drying and thermal stresses  Steel fiber reinforcing also increases the durability of the concrete surface Prestressing Prestressing  Theory; “Place all the concrete of the member in compression” (take advantage of concrete’s compressive strength of the entire member)  Advantages o Increase the load carrying capacity o Increase span length o Reduce the member’s size  Prestessing: Applying an initial compressive stress to a concrete member, so as to improve its structural efficiency.  High-strength steel strands are stretched tightly and then restrained by the concrete, putting the concrete into initial compression.  Prestressed members are typically more slender and lighter than comparable conventionally reinforced members.  Pretensioning: Steel strands are tensioned before concrete is cast. o Normally only done with concrete in precasting plants, but not on the construction site.  Posttensioning: Steel strands are tensioned after concrete has been cast and reached adequate strength. o Concrete cast on the construction site can be posttensioned. Prestressing - Posttensioning

 Cables positioned prior to concrete placement  Stressed after concrete placement (& curing) Additional Resources Videos  Tilt Up Construction Process Chapter 14 - Site Cast Concrete Thought Points  Focus on the process of casting a concrete slab on grade, wall and column and elevated concrete framing structures on site. Key Terms Slab on grade: A concrete surface lying upon, and supported directly by, the ground beneath. Slag: The mineral waste that rises to the top of molten iron or steel or to the top of a weld. Capillary break: A slot or groove intended to create an opening too large to be bridged by a drop of water and, thereby, to eliminate the passage of water by capillary action; the coarse aggregate layer under a concrete slab on grade which discourages the migration of water from the ground below into the concrete slab above. Moisture barrier: A membrane used to resist the migration of liquid water through a floor, wall, or roof. Screed: A strip of wood, metal, or plaster that establishes the level to which concrete or plaster will be placed. Bull float: A long-handled tool used for the initial floating of a freshly poured concrete slab. See also Darby. Darby: A stiff straightedge of wood or metal used to level the surface of wet plaster or concrete. Bleed water: In freshly placed concrete, water that rises to the top surface of the concrete as the solid cement and aggregate particles settle. Steel trowel: A metal-bladed tool used in the final stages of finishing of a concrete slab. Broom finish: A skid-resistant texture imparted to an uncured concrete surface by dragging a stiff-bristled broom across it. Restraightening: A step in the finishing of concrete slabs for the purpose of removing minor undulations produced during floating or troweling. Straightedge: To strike off the surface of a concrete slab using screeds and a straight piece of lumber or metal; as a noun, a long, straight item, used to perform straightedging, test the flatness of a surface, or trace a straight line. Shake-on hardener: A dry powder that is dusted onto the surface of a concrete slab before troweling to react with the concrete and produce a hard wearing surface for industrial use. Curing compound: A liquid that, when sprayed on the surface of newly placed concrete, forms a water-resistant layer to prevent premature dehydration of the concrete. Superflat floor: A concrete slab finished to a high degree of flatness and levelness according to a recognized system of measurement. F-number: An index number expressing the statistical flatness or levelness of a concrete slab. Control joint: An intentional, linear discontinuity in a structure or component designed to form a plane of weakness where cracking can occur in response to various forces so as to minimize or eliminate cracking elsewhere. Also called a contraction joint. Isolation joint: A type of joint used to separate abutting materials or assemblies that should remain structurally independent, such as where new construction meets old, or where a nonstructural slab on grade abuts structural columns or walls. Shrinkage-compensating cement: Specially formulated cement, used to counteract the drying shrinkage that normally occurs during curing. Key: A slot formed into a concrete surface for the purpose of interlocking with a subsequent pour of concrete; a slot at the edge of a precast member into which grout will be poured to lock it to an adjacent member; a mechanical interlocking of plaster with lath. Dowel: A short cylindrical rod of wood or steel; a steel reinforcing bar that projects from a foundation to tie it to a column or wall, or from one section of a concrete slab or wall to another. Form tie: A steel or plastic rod with fasteners on either end, used to hold together the two surfaces of formwork for a concrete wall. Waler: A horizontal beam used to support sheeting or concrete formwork. Form tie hole: A depression, typically conical in shape, in a cast-in-place concrete wall that remains after the protruding portions of a form tie are removed. Insulating concrete form (ICF): A system of lightweight components, most commonly made of rigid polystyrene insulating foam, used as permanent formwork for the casting of concrete walls. One-way solid slab: A reinforced concrete floor or roof slab that spans between parallel beams or bearing walls. Reshoring: Inserting temporary supports under concrete beams and slabs after the formwork has been removed to prevent overloading before the concrete achieves its full strength. Slab band: A very broad, shallow beam used with a one-way solid slab. One-way concrete joist system: A reinforced concrete framing system in which closely spaced concrete joists span between parallel beams or bearing walls. Pan: A form used to produce the cavity between joists in a one-way concrete joist system.

Distribution rib: A transverse beam at the mid-span of a one-way concrete joist structure, used to allow the joists to share concentrated loads. Joist band: A broad, shallow concrete beam that supports one-way concrete joists whose depths are identical to its own Wide-module concrete joist system: A one-way concrete framing system with joists that are spaced more widely than those in a conventional one-way concrete joist system. Two-way flat slab: A reinforced concrete framing system in which columns with mushroom capitals and/or drop panels directly support a two-way slab that is planar on both of its surfaces. Mushroom capital: A flaring comical head on a concrete column. Drop panel: A thickening of a two-way concrete structure at the head of a column. Middle strip: The half-span-wide zone of a two-way concrete slab that lies midway between columns. Two-way flat plate: A reinforced concrete framing system in which columns directly supporta two-way slab that is planar on both of its surfaces. Waffle slab: A two-way concrete joist system. Dome: An arch rotated about its vertical axis to produce a structure shaped like an inverted bowl; a form used to make one of the cavities in a concrete waffle slab. Head: The horizontal top portion of a window or door. Draped tendon: A posttensioning strand placed along a curving profile that approximates the path of the tensile forces in a beam. Set: To cure; to install; to recess the heads of nails; a punch for recessing the heads of nails. Lift-slab construction: A method of building multistory site-cast concrete buildings by casting all the slabs in a stack on the ground, then lifting them up the columns with jacks and welding them in place. Flying formwork: Large sections of slab formwork that are moved by crane. Slip forming: Building multistory sitecast concrete walls with forms that rise up the wall as construction progresses. Tilt-up construction: A method of constructing concrete walls in which panels are cast and cured flat on a floor slab, then tilted up into their final positions. Shotcrete: A low-slump concrete mixture that is deposited by being blown from a nozzle at high speed with a stream of compressed air; pneumatically placed Concrète. Architectural concrete: Concrete intended as a finish surface and produced to a higher-quality standard. Exposed aggregate finish: A concrete surface in which the coarse aggregate is revealed. Diamond saw: A tool with a moving chain, belt, wire, straight blade, or circular blade whose cutting action is carried out by diamonds. Barrel shell: A scalloped roof structure of reinforced concrete that spans in one direction as a barrel vault and in the other as a folded plate. Folded plate: A roof structure whose strength and stiffness derive from a pleated or folded geometry. Guided Reading Questions Answers 1. A concrete slab on grade is a level surface of concrete that lies directly on the ground. TRUE 2. Contraction Joints are not the same thing as control FALSE 3. Isolation joints are intentionally weakened sections created through the concrete slab where the tensile forces caused by concrete drying shrinkage are relieved. FALSE 4. Shrinkage cracking in sitecast concrete walls is managed with contraction joints. TRUE 5. A one-way solid slab spans across parallel lines of support furnished by walls or columns and beams. TRUE 6. Temporary, adjustable-length columns are called shores. TRUE 7. Ordinarily, the most efficient and economical concrete beam is one whose depth is the same size as its breadth. FALSE 8. The one-way concrete joist system is also called a ribbed slab. TRUE 9. Distribution ribs are broad beams that are only as deep as the joists. FALSE 10. The wide-module concrete joist system is needed for when a one-way solid slab span increases, and a progressively thicker slab is required, and the slab becomes so thick that its own weight becomes an excessive burden. FALSE 11. One-way framing systems are best suited to floor plans with rectangular framing bays. TRUE 12. A two-way solid slab system is very common. FALSE

13. Most two-way floor and roof framing systems, however, even for heavy loadings, are made with beams. FALSE 14. The two-way flat slab system is suited for heavily loaded buildings such as storage and industrial buildings. TRUE 15. Middle strips are designed to carry the higher bending forces encountered in the zones of the slab that cross the columns. Column strips have a lighter reinforcing pattern. FALSE 16. In more lightly loaded buildings, such as hotels, hospitals, dormitories, and apartment buildings, the slab needs to be thickened all over the columns. FALSE 17. Metal or plastic pans called domes are used as formwork to eliminate nonworking concrete from the slab, allowing considerably longer spans than are feasible with the two-way flat plate. TRUE 18. The waffle slab system is suited to longer-span, heavily loaded applications. TRUE 19. Waffle slab formwork is the cheapest and most used of sitecast framing systems. FALSE 20. Two-way concrete joist is the most expensive of all the sitecast concrete framing systems. TRUE 21. Posttensioning can be applied to any of the sitecast concrete framing systems. TRUE 22. Posttensioning is used in beams, girders, and slabs, both one-way and two-way, to reduce member sizes, reduce deflection, and extend spanning capability. TRUE 23. Two-way flat plate structures are not commonly posttensioned. FALSE 24. In tilt-up construction, reinforced concrete wall panels are cast lying down over a previously poured slab that serves as a level, smooth work surface. TRUE 25. Tilt-up construction increases most of the formwork and formwork costs normally required for sitecast concrete walls. FALSE 26. Insulating concrete forms (ICFs) serve to contain the concrete when the wall is poured, but unlike conventional formwork, also become a permanent part of the wall, for which they act as thermal insulation. TRUE 27. Insulating concrete forms are so heavy and are so roughly made that they are very hard to assemble. FALSE 28. Architectural concrete is sprayed into place from the nozzle of a hose by a stream of compressed air. FALSE 29. Long-span beams and trusses are not possible in concrete. FALSE 30. Barrel shells and folded plates derive their stiffness and strength from the folding or scalloping of a thin concrete plate to increase its rigidity and structural depth without adding material. TRUE 31. The cost of a concrete building frame can be broken down into the costs of the concrete, the reinforcing steel, and the formwork. TRUE 32. Climbing formwork is not the same thing as jump form construction. FALSE 33. Slip form construction is when the formwork progresses continuously, night and day, at a slow but steady prescribed rate, while construction proceeds within the formwork surrounds. TRUE

34. Concrete structures are extremely flammable. FALSE 35. Lift-slab construction is a system in which floor and roof slabs of a building are cast in a stack on the ground and then jacked up the building columns to their final elevations, where they fixed in place. TRUE 36. A slab-on-grade floor usually experiences a lot of structural stress. FALSE 37. A layer of 11/2-inch-diameter (38-mm) crushed stone at least 4 inches (100 mm) deep is called a capillary break. TRUE 38. Immediately after striking off the concrete, the slab receives its initial floating. TRUE 39. When concrete begins to stiffen and the watery sheen that evaporates from the surface of the slab is called dirty water. FALSE 40. Every concrete floor is perfectly flat. FALSE 41. Concrete slabs on grade are relatively thin in relation to their horizontal dimensions and normally only lightly reinforced, they are prone to cracking. TRUE 42. The most common method of controlling cracking in concrete slabs on grade is to introduce an organized system of joints into the slab that allow cracking to occur in a neat and visually acceptable pattern. TRUE 43. Form ties are small-diameter steel rods specially shaped to hold the formwork together under the pressure of the wet concrete. TRUE 44. It doesn’t matter what consistency concrete has when it is poured. FALSE 45. Isolation joints are used where cast concrete walls abut other structural elements, and each must remain independent of the other. TRUE 46. A concrete column is formed and cast the exact same way as a wall. FALSE 47. One-way concrete joists are usually supported on joist bands, which are broad beams that are only as deep as the joists. TRUE 48. Waffle slab form work is very simple. FALSE 49. Two-way concrete joist is the most expensive of all the sitecast concrete framing systems. TRUE 50. In tilt-up construction, reinforced concrete wall panels are cast lying down over a previously poured slab that serves as a level, smooth work surface. TRUE Guided Reading Questions Concrete Construction - Options Concrete Construction - Options  Cast off Site (Precast) o Construct components prior to installation o Transport components to the project (if cast “off” site) o Assemble / Erect the concrete elements  Cast on Site (Site Cast) o Labor, Material, & Equip. brought to the site, and

o Concrete elements constructed in-place  Combination Types of Concrete Elements That Must be Cast on Site  Caissons & Pile Caps  Footings (Spread & Strip)  Slab-on-Grade  Slab Toppings  Elements too large or heavy to Transport  Irregular or Special Elements (typically)  Structures Requiring Full Structural Continuity Types of Concrete Elements  Slab-on-Grade  Columns  Walls  Floors & Roofs  Other (stairs, panels, etc.) Casting on a Concrete Slab on Grade Concrete Slabs  Slab On Grade: A concrete surface, lying upon, and continuously supported by, the ground beneath.  Suspended or Structural Concrete Slab: A concrete slab that spans between intermediate lines or points of support. SOG: Subgrade Preparation  Site is cleared and grubbed if necessary.  Organic top soil is removed .  Subsoil , or subgrade, is excavated to required depth.  Subgrade is graded level and compacted to the required density.  If the subsoil is too soft or unstable, it is over-excavated and replaced with more competent material.  Proof rolling : A heavy roller or loaded dump truck makes multiple passes over the subgrade (right). Areas that are revealed to be soft or unstable are corrected. SOG: Capillary Break or Drainage Layer  A layer of crushed rock or gravel , usually 4 inches deep, is placed over the subgrade.  This rock material is well sorted (comprised of particles mostly uniform in size), that may range from approximately ¾-inch to 1½-inch in diameter.  This layer drains water easily and discourages moisture in the ground from rising up to the concrete slab through capillary action.  This layer also provides a structurally sound base for the concrete slab to follow. SOG: Slab Edges  Edge forms : Strips of wood or metal are placed to contain the concrete pour at the slab edges.  Forms are held in place by stakes of wood or metal rebar , or other bracing.  The tops of the forms are set level with the top the slab , to act as guides in later finishing operations.  Isolation or expansion joints: Where slabs abut walls, columns, or other elements, compressible joint material is placed to create an isolation joint or expansion joint.  Isolation joints allow unrestrained expansion and contraction of the slab , as well as differential settling between the slab and the abutting elements. SOG: Vapor Retarder or Moisture Barrier  A heavy plastic sheet or other impervious material may be laid over the drainage layer.  This layer provides the slab with additional protection against subgrade moisture and is particularly important when the slab will be covered with moisture-sensitive finishes.  Vapor retarders are used only with interior slabs , not with exterior slabs.  Vapor retarder materials must be durable enough to resist being punctured or torn during subsequent construction operations , such as laying reinforcing steel or pouring the concrete.  Penetrations and tears in the vapor retarder are sealed tightly to maintain a continuous barrier.  In cases of extreme ground water conditions, the moisture barrier may be replaced with a heavier, more impervious waterproofing membrane.

SOG: Reinforcing  A grid of reinforcing bars or sheets of welded wire reinforcing (WWF) is usually placed.  Reinforcing improves a slab's resistance to cracking due to: o concrete shrinkage during curing o effects of thermal expansion and contraction o concentrated stresses o differential settlement  This reinforcing is sometimes called temperature steel., referring to its role in resisting cracking due to thermal stresses. SOG: Pouring the Concrete  Concrete is placed by any of a number of methods, depending on the size of the pour and ease of access to the slab. o Concrete delivered by pumper o Concrete delivered by wheel barrow  Concrete should be placed as close as possible to its final destination .  Pushing concrete along the ground can cause segregation of large and small particles in the concrete mix, leading to a lack of uniform density and uneven finish qualities in the completed slab.  If the reinforcing has not been set on bolsters or other supports, it must be lifted into approximately the middle depth of the slab as the concrete is poured. SOG: Finishing the Concrete  Striking off or screeding: A wood plank or metal straightedge is drawn across the surface of the freshly poured concrete, using an end-to-end sawing motion.  A bulge of concrete is maintained in front of the screed, to fill low spots as the screed progresses.  Striking off establishes the elevation of the upper slab surface.  Floating: Immediately after screeding, floating is performed to consolidate and smooth the slab surface .  A bull float is drawn back and forth over the slab.  A darby is used to float areas of the slab that can be reached without the long arm of the bull float  Further finishing operations depend on the type of final finish required for the slab.  Where a rough finish is acceptable, no further operations may be required.  When required, further finishing steps begin after the concrete has been allowed to stiffen, and free water that rises to the surface, called bleed water, has evaporated.  Edgers and groovers are used to create neatly formed, well-consolidated edges and joints in the slab surface.  Floating may be performed a second time, to further consolidate and densify the surface of the slab.  Floats are made of wood or metal with a slightly rough surface. The floating operation leaves the slab with a lightly textured surface.  Floating may be done by hand, or with power machinery.  Troweling: For a smoother finish, the slab is troweled immediately after floating.  Trowels are made of smooth-surfaced steel or other metal. Troweling may performed by hand or with power-operated machinery.  Broom Finish: A stiff broom is drawn across the slab surface to create a striated, slip resistant texture (right)  Restraightening: After each floating or troweling operation, a long straightedge may be drawn over the slab surface to reduce minor undulations  Shake-On Hardeners: Dry powders may be floated into the slab surface to create a harder, more durable surface  Laser Screeds: Laser-guided power screeds can be used to finish slabs to more precise flatness and levelness requirements.  Curing: To ensure proper curing of the concrete, freshly poured slabs must be kept damp for at least the first week.  Slabs are especially vulnerable to premature drying because of their relatively large exposed surface area: o Cover slab with impervious plastic sheets (right). o Cover slab with absorbent, dampened straw, sawdust, or burlap. o Coat slab with a liquid-applied curing compound, that dries to form a clear moisture barrier. SOG: Controlling Cracking  Relatively thin, lightly reinforced concrete slabs on grade are especially prone to cracking, especially as the concrete shrinks during curing.

 Control joint or contraction joint: A partial-depth joint or groove that creates a natural plane of weakness in the slab.  Control joints encourage shrinkage cracking to occur in an organized , visually acceptable manner.  Control joints may be saw-cut into a slab after the slab has partially hardened.  Control joints can also be formed during slab finishing operations using hand tools called groovers .  Control joints need to extend at least ¼ the depth the slab to be effective.  As a rule of thumb, control joints should be spaced from 24 to 30 times the depth of the slab. (E.g., for a 4-inch slab, joints should be spaced no more than 8 to 10 feet in both directions.)  Expansion joint or isolation joint: Expansion and isolation joints are full-depth separations between slab sections , that allow full freedom of movement between sections.  Reinforcing is also interrupted across expansion joints. (Across control joints, reinforcing is usually uninterrupted .)  Other means of crack control: o Concrete mixtures can be adjusted to reducing drying shrinkage. o Additional reinforcing or posttensioning can be added to a concrete slab to increase its tensile strength. Casting a Concrete Wall Wall Footing  Concrete walls are most commonly cast over concrete strip footings .  The steel reinforcing projecting from the footing will overlap with reinforcing in the wall , to structurally tie the two elements. Reinforcing  The size, spacing, and arrangement of reinforcing bars varies with the structural requirements of the wall.  Typically, reinforcing is placed in one or two layers of vertical and horizontal reinforcing bars.  Reinforcing for a concrete shear wall (designed to resist lateral forces such as wind or earthquake), consisting of two layers of vertical and horizontal bars .  The wall is reinforced more heavily at either end, where it must resist greater stresses.  Heavy reinforcing at the base of concrete shear walls for a large, multistory building. Wall Forms  Slender rods, called form ties , hold the forms in position and resist the outward pressure of the concrete when it is placed.  The plastic cones prevent the formwork for sliding along the ties, and form a neat, conical hole in the finished surface of the concrete.  Form ties can be made from steel rods, straps, wire, fiberglass, or other plastics.  After the wall is cast and the forms removed, the protruding ends of the metal ties are broken off and the plastic cones removed.  The remaining holes in the concrete may be left open, filled with mortar (right), or plugged with some other material .  If the broken end of a metal form tie rod is not covered , rust staining may result as the end of the tie gradually corrodes.  Fiberglass form tie rods may be used without plastic cones . The protruding ends of the rods are simply ground off flush with the face of the concrete, becoming virtually unnoticeable to the untrained eye.  On the outside, the form ties engage with slotted metal wedges. The wedges restrain the horizontal walers.  The walers (and sometimes vertical studs) brace the formwork panels.  Wall forms must be constructed sufficiently stiff to resist the fluid pressures of the freshly poured concrete .  A proprietary, modular wall form system, that can be easily raised and reused as wall construction proceeds upwards.  Note the temporary scaffolding integrated into the form system , providing workers with access to the top of the wall.  Heavy, braced formwork for a large, free-standing concrete wall.  Self-climbing formwork relies on hydraulic jacks to climb the concrete core structure as it is constructed. Pouring Concrete  Concrete is placed in the wall.  It is consolidated by vibrating or hammering on the sides of the formwork.  The of the wall is struck off level .  The top of the wall is covered to limit water loss , and the wall is left to cure .  After several days, the formwork may be stripped . Curing should continue for at least one week. Finishing the Concrete  A residential concrete foundation wall with the formwork stripped.

 Without special efforts, the form panels and ties leave strong patterns on the wall surface.  A concrete foundation wall with blockouts to create openings in the wall for passage of building services .  Poor quality formwork construction leads to defects in the concrete wall that do not become evident until the formwork is removed.  Incomplete consolidation leads to a rock pocket in the concrete wall.  Note the exposed reinforcing bar .  Unsound concrete will be removed and the area patched . Controlling Cracking  Like slabs, concrete walls are susceptible to cracking due to concrete shrinkage during curing, thermal stresses, and other effects.  Vertical control joints , spaced at 24 to 30 times the thickness of the wall, can be formed in the wall to organize and conceal shrinkage cracks.  Full-depth expansion joints can also be inserted at larger spacings, if required. Insulating Concrete Forms (ICF)  Concrete forms made from rigid plastic foam blocks or other lightweight insulating materials are easy to erect.  The forms become a permanent part of the structure, creating a more energy efficient wall in comparison to conventional concrete construction. Tilt-Up Construction  Concrete wall panels are poured lying flat , much like a slab on grade.  Once the panels have gained sufficient strength, they are lifted into final position.  Tilt-up construction significantly reduces formwork costs , which can account for 50% or more of the cost of conventional concrete construction. Casting a Concrete Column Column Footings  Columns may rest on isolated footings, pile caps, caissons, or enlarged portions of strip footings .  The lower layer of reinforcing has been placed for an isolated footing. Additional reinforcing, including vertical dowels that will project out of the footing and overlap with vertical reinforcing bars in the column, will be added next. Column Reinforcing  Vertical reinforcing bars increase the column's load carrying capacity and give it resistance to bending forces generated by lateral forces on the building structure or by connected beams.  Ties , lighter in weight, wrap around the vertical bars to resist outward buckling of the bars .  Ties also increase a column's resistance to extreme cyclical seismic loads .  The arrangement of ties varies with the quantity and arrangement of vertical bars.  Vertical bars in a rectangular column are arranged 3 deep and 4 wide.Ties wrap around and cross through the vertical bar array .  Vertical bars are bent inward at the top , so as to nest with the next section of reinforcing as construction proceeds upward.  The length of the overlapping portions of reinforcing are sufficient to fully transfer stresses from one set of bars to the next.  Prefabricated column reinforcing stacked on site, ready to be lifted into position. Column Forms  Column forms may be square, rectangular, or round.  Unless the column is unusually wide, no form ties are required.  A reusable column form is maneuvered into place around column reinforcing.  The vertical bars in this column are bent horizontally at their top ends, to engage with steel reinforcing in the not-yet-constructed concrete slab. Material  Wood o Field fabricated or o Standardized panels  Steel  Plastic or Fiberglass  Waxed cardboard Typically - Ties not required  (Column Clamps)

Pouring Concrete  Concrete is deposited into the column form by any number of means.  The concrete is vibrated or otherwise consolidated as needed as it is placed.  A concrete bucket lifted by a construction crane is used to deliver concrete to the column form. Finishing Concrete  A partially-completed concrete column with the formwork recently removed. Elevated Framing Systems Elevated Framing Systems  One-Way System o Spans across parallel lines of support furnished by walls and/or beams  Two-Way System o Spans supports running in both directions One-Way Floor and Roof Framing Systems One-Way Solid Slab  A system of beams support a slab . The slab is reinforced to span in one direction only. o Girders (deeper beams) span between columns. o Beams (shallower) span from girder to girder. o The slab spans between the beams.  Depending on beam and column arrangements, this system can be designed for a wide range of load conditions .  Forming for girders and beams makes this system more expensive than many other systems.  Principal slab reinforcing spans in only one direction, from beam to beam. One-Way Concrete Joist (Rib Slab)  A system of beams and slender, closely-space ribs support a one-way slab. o Beams span between columns. o Joists (ribs) span from beam to beam. o The slab spans between the joists.  Greater spans are possible than with solid slab .  Modular, prefabricated form systems help to keep this system economical.  In one-way joist systems, the bottoms of the beams and joists are all on the same plane , simplifying formwork construction.  A simple, level surface is formed on site. Next, prefabricated metal or fiberglass joist pans are placed on this surface to form the system of beams and ribs . Wide-Module Concrete Joist System  Like one-way joist, but ribs are spaced 4 to 6 feet rather than 20 to 30 inches.  A thicker slab is required to span the greater distance between ribs (useful when greater thickness is required for greater fire resistance).  Also called "skip-joist" system. Two-Way Floor and Roof Framing Systems Two-Way Framing Systems  A two-way slab is reinforced so that it spans structurally in both directions.  Two-way slabs are more structurally efficient than one-way slabs of the same thickness.  Two-way slabs must span roughly the same distance in both directions. As the layout of slab supports becomes increasingly rectangular in proportion, the efficiency of the two-way slab decreases.  In contrast, one-way slab systems are more suitable for column and beam layouts that create rectangular bays. Two-Way Solid Slab  A system of beams supports a two-way slab .  Suitable for very heavy loads .

 Forming of the beam systems tends to make this system more expensive than other two-way slab systems.  A two-way reinforced slab is supported by columns without beams.  The flat slab system includes added structure where columns meet slabs: o Mushroom capitals : Conical widening toward the top of the column o Drop panels : Thickening of the slab around the column  This added structure allows the system to carry heavier loads than would otherwise be feasible. Two-Way Flat Slab Reinforcing  Between columns, more heavily-reinforced column strips act like shallow beams within the depth of the slab.  Between column strips, middle strips are reinforced for two-way slab action. Two-Way Flat Slab  A two-way flat slab with dropped panels , but no column capitals.  The extra structure around the column/slab juncture prevents the columns from "punching through" the slab . Two-Way Flat Plate  Like the flat slab, a two-way reinforced slab is supported by columns without beams .  There are no column capitals or drop panels in the flat plate system.  Additional reinforcing within the depth of the slab at the column/slab junction is used to increase strength in that area.  Flat plate systems are best suited to lighter loads than flat slab systems. The simplified formwork also makes them less expensive to construct.  A cross-shaped array of shear studs provides additional strength at the column/slab junction of a two-way flat plate system.  The green cables are posttensioning strands, as discussed in the last chapter.  The absence of forming for beams, column capitals, or drop panels shows this to be a two-way flat slab system.  Two-way flat plate construction in a residential tower.  Two-way flat plate is one of the thinnest of floor framing systems available in any structural material, an economy that is compounded in multi-story construction.  Note the reshoring (yellow clad columns) in use underneath the upper two slabs. When the formwork is removed, reshoring is inserted to provide support for the slabs until the concrete gains additional strength . Two-Way Waffle Slab (Two-Way Concrete Joist)  Similar to one-way joist, but with a two-way system of ribs  Constructed with prefabricated domes that simply formwork construction.  Around the columns, domes are filled solid to create heads that strengthen the column/slab connection, like drop panels in flat slab construction. Site Cast Post-tensioning Systems Site Cast Post-tensioning Systems  Can be used with any framing system  Reduce member size and/or  Extend span capacity Innovations in Site Cast Concrete  Lightweight Concrete and Admixtures  Formwork Materials & Methods  Lift-Slab  Flying Formwork, Gang forms  Slip Forms  Tilt-Up Lift-Slab  Cast slabs on the ground (“Stacked) & Jack into Place, and Anchored Additional Resources Video

 Precast Concrete Walls  Insulated Site-Cast Concrete Tilt Walls Chapter 15 – Precast Construction Thought Points  Focus on the standard types of precast and prestressed concrete elements, their manufacture and construction methods. The different method for joining. Key Terms Precast concrete: Concrete cast and cured in a location other than its final position in the structure. Steam curing: Aiding and accelerating the setting reaction of concrete by the application of steam. Solid slab: A concrete slab, without ribs or voids, that spans between beams or bearing walls. Hollow-core slab: A precast concrete slab element that has internal longitudimal cavities to reduce its self-weight. Double tee: A precast concrete slab element that resembles the letters TT in cross section. Single tee: A precast slab element whose profile resembles the letter T. Topping: A thin layer of concrete cast over the top of a floor deck. Ledger: A horizontal wood member fastened to a wall or beam to which the ends of joists may be connected. Casting bed: A permanent, fixed form in which precast concrete elements are produced. Weld plate: A steel plate anchored into the surface of concrete, to which another steel element can be welded. Carbon fiber reinforcing: In precast concrete, an open grid fabric of carbon fibers bonded with epoxy resin, used as a substitute for welded wire reinforcing Corbel: A spanning device in which masonry units in successive courses are cantilevered slightly over one another; a projecting bracket of masonry or concrete. Bearing pad: A block of plastic or synthetic rubber used to cushion the point at which one precast concrete element rests upon another. Anchor bolt: A bolt embedded in concrete for the purpose of fastening a building frame to a concrete or masonry foundation. Powder-driven: Inserted by a gunlike tool using energy provided by an exploding charge of gunpowder. Filigree precast concrete: A hybrid concrete system in which precast concrete sections are used as permanent formwork for cast-in-place concrete. Precast Concrete What Can Be Precast?  Slab Elements  Beams (& Girders)  Columns  Wall Panels  Other Precast Concrete Advantages  Production @ Ground Level  Controlled Environment (Plant vs. Jobsite)  High Quality Formwork (Often steel, reuse)  High Quality Materials (5000 psi conc., HSS)  Controlled Curing (High Early, steam cure, 24hr cycle)  Erection Time & Conditions (quicker, no formwork required, no temperature restraints – concrete already cured) Disadvantages  Elements large & heavy o Transportation o Site Mobility o Hoisting / Erection

 Less field modification flexibility  Often Require a Topping Slab Plant-Cast Precast Concrete  On the construction site, precast concrete elements are lifted into place and assembled into structural assemblies in a process similar to that used for structural steel.  Compared to sitecast concrete, precast concrete erection is faster and less affected by adverse weather conditions . Precast Prestressed Concrete Structural Elements Precast Concrete Slabs  Used for floor and roof decks .  Deeper elements span further than those that are shallower. Precast Concrete Beams & Girders  Provide support for slabs .  The projecting reinforcing bars will bond with concrete cast on site. Precast Concrete Columns & Wall Panels  Provide support for beam and slab elements .  Since these elements carry mainly axial loads with little bending force, they may be conventionally reinforced without prestressing .  Wall panels can be ribbed , to increase their vertical span capacity while minimizing weight, or formed into other special shapes.  Precast concrete wall panels may be solid , hollow, or sandwiched (with an insulating core). Other Precast Concrete Elements  Precast concrete stairs  Uniquely shaped structural elements for a sports stadium Assembly Concepts for Precast Concrete Buildings  Vertical support can be provided by precast columns and beams , wall panels , or a combination of all three.  The choice of roof and floor slab elements depends mainly on span requirements .  Precast slab elements are frequently also used with other vertical loadbearing systems such as sitecast concrete, reinforced masonry, or steel .  Precast concrete structure consisting of solid wall panels and hollow core slabs .  A single story warehouse consisting of double tees supported by insulated sandwich wall panels . Parking Garage  A parking garage structure consisting of precast double tees supported by inverted tee beams on haunched columns. Manufacturing of Precast Concrete Structural Elements Casting Hollow Core Planks  Precast elements are manufactured in casting beds , 800 ft or more in length.  High-strength steel strands are strung the length of the bed and tensioned.  Conventional reinforcing, weld plates, blockouts, lifting loops, and other embedded items are added as needed.  Concrete is placed . Prestressing and Reinforcing Steel  Many precast elements contain both prestressing strands and conventional reinforcing.  The prestressing strands for an AASHTO girder are depressed into a shallow v-shape to most efficiently resist tensile forces in the beam. Shear stirrups are formed from conventional steel reinforcing. Reinforcement  Structural elements are commonly reinforced with tightly stretched pretensioned steel strands, which provide increased structural efficiency.  Conventional steel reinforcing is added for resistance to thermal and other secondary stresses. Casting Hollow Core Planks  Once the concrete has cured to sufficient strength, the castings are cut into sections of desired length.  In some cases, transverse bulkheads are inserted to divide the casting bed into sections before concrete is placed. In this case, only the prestressing strands need to be cut to separate the sections.  Individual sections are lifted from the casting bed and stockpiled to await shipping to the construction site.  Precast concrete elements are shipped to the construction site by truck and erected on site by crane .

Precast Slab Manufacturing  Casting Beds  Reinforcing & Embeds  Pour, Finish, & Cure o Validate Strength  Removal from Bed (Transfer stress to Member)  Plant Storage or Transport to the Jobsite Precast Slab Erection  Transportation to the Job Site  Erection  Anchorage  Bearing Pads  Topping Slabs Joining Precast Concrete Elements Joining Precast Concrete Elements  Bolting, welding and grouting  Gravity- beam rests on the corbel of a column o Bearing pads- avoid grinding & allows for expansion and contraction Column-to-Column Connection  Metal bearing plates and embedded anchor bolts are cast into the ends of the columns.  After the columns are mechanically joined , the connection is grouted to provide full bearing between elements and protect the metal components from fire and corrosion. Beam-to-Column Connection  Beams are set on bearing pads on the column corbels .  Steel angles are welded to metal plates cast into the beams and columns and the joint is grouted solid. Slab-to-Beam Connection  Hollow core slabs are set on bearing pads on precast beams.  Steel reinforcing bars are in inserted into the slab keyways to span the joint.  The joint is grouted solid.  The slab may remain untopped as shown, or topped with several inches of cast in place concrete. Sitecast Concrete Toppings over Precast Slabs  Greater floor strength and stiffness  Greater fire resistance  Greater acoustic isolation  Allow easy integration of electrical services into floor system  Create a smoother, flatter floor surface. Precast Concrete Construction and Seismic Design  In areas of high seismic risk, structures must be designed to respond safely to the dynamic forces imparted into the structure.  Innovations in joint design are improving the connection systems in precast concrete structures and making them increasingly suitable for use in such areas. Precast Elements and Other Structural Materials Precast Used with other Structural Materials  Precast & Cast-in-Place Concrete  Precast & Masonry  Precast & Structural Steel

MODULE 3 Table of contents  Weekly Readings  Chapter 8 – Brick Masonry o Key Terms o Guided Reading Questions o Masonry History o Mortar o Brick Masonry o Additional Resources  Chapter 9 - Stone and Concrete Masonry o Key Terms o Guided Reading Questions o Stone versus Brick o Stone Masonry o Stone Masonry – Process o Concrete Masonry – CMU Manufacturing Process o Concrete Masonry – CMU Installation Process o CMU Decorative or Architectural o Additional Resources  Chapter 10 –Masonry Wall Construction o Key Terms o Guided Reading Questions o Types of Masonry Walls o Spanning Systems For Masonry Bearing Wall Construction o Detailing Masonry Walls o Special Problems in Masonry Construction o Additional Resources Weekly Readings This week you will need to read Chapters 8, 9 and 10 in your textbook. Chapter 8 – Brick Masonry Thought Points  Focus on the function and production methods of mortar, and bricks. The production method, characteristics and consideration for brickwork. Key Terms Mason: One who builds with bricks, stones, or concrete masonry units; one who works with concrete. Masonry unit: A brick, stone, concrete block, glass block, or hollow clay tile intended to be laid in mortar.

Trowel: A thin, flat steel tool, either pointed or rectangular, provided with a handle and held in the hand, used to manipulate mastic, mortar, plaster, or concrete. Also, a machine whose rotating steel blades are used to finish concrete slabs; to use a trowel. Mortar: A substance used to join masonry units, consisting of cementitious materials, fine aggregate, and water. See also Cement-lime mortar, Lime mortar. Cement—lime mortar: Mortar made from portland cement, hydrated lime, aggregate, and water, the most traditional formulation of modern masonry mortars. See also Masonry cement, Mortar cement. Aggregate: Inert particles, such as sand, gravel, crushed stone, or expanded minerals, in a concrete, mortar, or plaster. Portland cement: A gray or white powder, composed principally of calcium silicates, which, when combined with water, hydrates to form the binder in concrete, mortar, and stucco. Lime: A nonhydraulic cementitious material, used as an ingredient in mortars and plasters. See also Hydrated lime, Quicklime. Quicklime: Produced by burning calcium carbonate found in limestone or sea shells; once hydrated, used as an ingredient in mortars and plasters; chemically, calcium oxide. Soft mud process: Making bricks by pressing wet clay into molds. Sand-mold brick, sand-struck brick: A brick made in a mold that was wetted and then dusted with sand before the clay was placed in it. Stiff mud process: A method of molding bricks in which a column of damp clay is extruded from a rectangular die and cut into bricks by fine wires. Blended hydraulic cement: Hydraulic cement made from a mixture of cementitious materials such as portland cement, other hydraulic cements, and pozzolans for the purpose of altering one or more properties of the cement or reducing the energy required in the cement manufacturing process. Masonry cement: A hydraulic cement made from a blend of portland cement, lime, and other dry admixtures designed to increase the workability of the mortar. See also Cement-lime mortar. Air-entraining admixture: An admixture that causes a controlled quantity of stable microscopic air bubbles to form in concrete or mortar during mixing, usually for the purposes of increasing workability and resistance to freeze- thaw conditions. Mortar cement: In masonry, a blend of portland cement, lime, and other additives, that produces mortar comparable in its bond strength properties to cement-lime mortar. See also Cement-lime mortar . Hydraulic cements: Cementitious materials, such as portland cement or blast furnace slag, that harden by reacting with water and whose hardened products are not water soluble. Nonhydraulic cements, such as lime, can also be mixed with pozzolans to create cements with hydraulic properties. Lime mortar: Masonry mortar made from a mix of lime, sand, and water; used principally in the restoration of historic Structures. Nonhydraulic cements: Cementitious materials, such as gypsum and lime, that remain water soluble after curing. See also Hydraulic cements. Carbonation: The process by which lime mortar reacts with atmospheric carbon dioxide to cure. Hydration: The process by which cements combine chemically with water to harden. Extended-life admixture: A substance that retards the onset of the curing reaction in mortar so that the mortar may be used over a protracted period of time after mixing. Efflorescence: A light-colored, powdery deposit on the face of masonry or concrete, caused by the leaching of chemical salts from water migrating from within the structure to the surface. Soft mud process: Making bricks by pressing wet clay into molds. Water-struck brick: A brick made in a mold that was wetted before the clay was placed in it. Dry-press process: A method of molding slightly damp clays and shales into bricks by forcing them into molds under high pressure. Stiff mud process: A method of molding bricks in which a column of damp clay is extruded from a rectangular die and cut into bricks by fine wires. Firing: The process of converting dry clay into a ceramic material through the application of intense heat. Periodic kiln: A kiln that is loaded and fired in discrete batches, as differentiated from a tunnel kiln, which is operated continuously. Tunnel kiln: A kiln through which clay products are passed on railroad cars. Water smoking: The process of applying heat to evaporate the last water from clay products before they are fired. Oxidation: Corrosion; rusting; rust; chemically, the combining with oxygen. Vitrification: The process of transforming a material into a glassy substance by means of heat. Flashing: A thin, continuous sheet of metal, plastic, rubber, or waterproof paper used to prevent the passage of water through a joint in a wall, roof, or chimney. Building brick: Brick used for concealed masonry work where appearance is not a concern. Hollow brick: Clay brick with up to 60 percent void area. Firebrick: A brick made to withstand very high temperatures, as in a fireplace, furnace, or industrial chimney. Wythe: (rhymes with “scythe" and “tithe") A vertical layer of masonry that is one masonry unit thick. Course: A horizontal layer of masonry units one unit high; a horizontal line of shingles or siding. Bed joint: The horizontal layer of mortar beneath a masonry unit." Head joint: The vertical layer of mortar between ends of masonry units. Collar joint: The vertical mortar joint between wythes of masonry. Stretcher: A brick or masonry unit laid in its most usual position, with the broadest surface of the unit horizontal and the length of the unit parallel to the surface of the wall. Header: In framed construction, a member that carries other perpendicular framing members, such as a beam above an opening in a wall or a joist supporting other joists where they are interrupted by a floor opening. In steel construction, a beam that spans between girders. In masonry construction, a brick or other masonry unit that is laid across two wythes with its end exposed in the face of the wall.

Soldier: A brick laid on its end, with its narrow face toward the outside of the wall. Rowlock: A brick laid on its long edge, with its end exposed in the face of the wall. Structural bond: The interlocking pattern of masonry units used to tie two or more wythes together in a wall. Common bond: Brickwork laid with five courses of stretchers followed by one course of headers. Flemish bond: Brickwork laid with each course consisting of alternating headers and stretchers. English bond: Brickwork laid with alternating courses, each consisting entirely of headers or stretchers. Cavity wall: A masonry wall that includes a continuous airspace between its outermostwythe and the remainder of the wall. Guided Reading Questions Answers 1. Iron and steel began replacing masonry in architecture in the late 19 th century. TRUE 2. The 19 th -century invention of the hollow concrete block was much cheaper than cut stone and required much less labor to lay than brick. TRUE 3. Mortar cushions the masonry units, giving them full bearing against one another despite their surface irregularities. TRUE 4. Mortar seals between masonry units are susceptible to water and wind penetrating it. FALSE 5. The simplest type of mortar is cement-lime mortar, made of portland cement, hydrated lime, an inert aggregate, and water. TRUE 6. The lime in cement-lime mortar is responsible for making the sealant cure. FALSE 7. Lime is produced by burning limestone or seashells in a kiln to drive off carbon dioxide and leave quicklime, which is then slaked by adding water that chemically combines with it to form hydrated lime. TRUE 8. The slaking process requires a large quantity of heat to be produced. FALSE 9. Water is an important ingredient in mortar because it is chemically involved in the curing of the cement and lime. TRUE 10. Water used in mortar should be distilled and room temperature. FALSE 11. Masonry cements contain various cements, lime, additional plasticizing ingredients, and other additives. TRUE 12. Air-entraining admixtures result in a higher air content in the cured mortar than cement-lime mortar. TRUE 13. Set accelerators reduce staining that forms on the surface of a wall when excess moisture carries minerals from the mortar to the wall surface. FALSE 14. The thermal mass properties of brick masonry can help to reduce building energy consumption by lessening peak cooling and heating loads. TRUE 15. Brick manufacturing produces significant waste materials. FALSE 16. As a product of fire, brick is the most resistant to building fires of any masonry unit type. TRUE 17. Larger bricks are less likely to crack during drying or firing than smaller bricks. FALSE 18. The dry-press process is used for clays that shrink excessively during drying. TRUE 19. The first steps of firing bricks in a kiln are water smoking and dehydration. TRUE 20. The higher the temperature used in firing bricks, the lesser the shrinkage and lighter the color of the brick. FALSE

21. In comparison to the traditional kiln brick firing process, steam curing of fly ash bricks requires significantly less energy and can have significantly less environmental impact than clay bricks. TRUE 22. There is no truly standard brick. TRUE 23. Facing bricks are only intended for nonstructural uses where appearance is important. FALSE 24. Cored and frogged bricks are not considered a solid unit because up to 25 percent of the brick may be void. FALSE 25. Brick-grade establishes levels of durability for bricks by characterizing bricks’ resistance to freeze-thaw weathering. TRUE 26. Brick type defines limits on the variation in size, distortion in shape, and chippage among brick units. TRUE 27. A brick wall constructed with a running bond is not a structural bond. TRUE 28. When the leads of a brick wall have been completed, a mason’s line is stretched between the leads, using L-shaped line blocks at each end to locate the end of the line precisely at the top of each course of bricks. TRUE 29. Thicker mortar joins require a stiffer than normal mortar that is difficult to work with but allows greater tolerances in brick sizes. TRUE 30. Outoor joints in brickwork can be tooled raked, stripped, or struck to accentuate the pattern of bricks in the wall in various ways. FALSE 31. Brick walls must be supported above openings for windows and doors by structures such as lintels. TRUE 32. A corbel is a recent structural device that allows bricks to span large openings in brick walls. FALSE 33. Brick vaults and domes, if their lateral thrusts are sufficiently tied, or buttressed, are strong, stable forms. TRUE 34. A reinforced brick wall is normally created by constructing to wythes of brick 2 to 4 inches apart and filling the cavity with reinforced concrete. FALSE 35. Low-lift grouting is an ancient practice used in reinforced brick walls that is no longer used due to its propensity for water damage. FALSE 36. High-lift grouting employs the use of temporary cleanout holes in the lowest course of masonry so the cavity can be periodically flushed from above with water. TRUE 37. Reinforced masonry walls are much stronger and better able to resist the dynamic stresses of earthquakes than unreinforced brick walls. TRUE Running bond: Brickwork consisting entirely of stretchers. Lead: (rhymes with “bed”) A soft, dull gray, easily formed nonferrous metal. Lead: (rhymes with “bead") In masonry work, a corner or wall end accurately constructed with the aid of a spirit level to serve as a guide for placing the bricks in the remainder of the wall. Story pole: A strip of wood marked with the exact course heights of masonry for a particular building; used to make sure that all the leads are identical in height and coursing. Weathered joint: A mortar joint finished in a sloping, planar profile that tends to shed water to the outside of the wall. Vee joint: A joint whose profile resembles the letter V. Concave joint: A mortar joint tooled into a curved, indented profile.

Muriatic acid: Hydrochloric acid. Lintel: A beam that carries the load of a wall across a window or door opening. Corbel: A spanning device in which masonry units in successive courses are cantilevered slightly over one another; a projecting bracket of masonry or concrete. Arch: A structural device that supports a vertical load by translating it into axial inclined forces at its supports. Centering: Temporary formwork for an arch, dome, or vault. Spandrel: The wall area between the head of a window on one story and the sill of a window on the floor above; the area of a wall between adjacent arches. Gauged brick: A brick that has been rubbed on an abrasive stone to reduce it to a trapezoidal shape for use in an arch. Rough arch: An arch made from masonry units that are rectangular rather than wedge-shaped. Barrel vault: A segment of a cylindrical surface that spans as an arch. Dome: An arch rotated about its vertical axis to produce a structure shaped like an inverted bowl; a form used to make one of the cavities in a concrete waffle slab. Buttress: A structural device, usually of masonry or concrete, that resists the diagonal forces from an arch or vault. Reinforced brick masonry (RBM): Brickwork into which steel bars have been embedded to impart tensile strength to the construction, Grout: A high-slump mixture of portland cement, aggregates, and water, which can be poured or pumped into cavities in concrete or masonry for the purpose of embedding reinforcing bars and/ or increasing the amount of loadbearing material in a wall; a specially formulated mortar-like material for filling under steel baseplates and around connections in precast concrete framing; a mortar used to fill joints between ceramic tiles or quarry tiles. Static coefficient of friction (SCOF): The coefficient of friction, measured between two surfaces at rest relative to each other; used in some finish flooring slip resistance measurements. See also dynamic coefficient of friction . Low-lift grouting: A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in increments not higher than 4 feet (1200 mm). High-lift grouting: A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in story-high increments. Cleanout hole: An opening at the base of a masonry wall through which mortar droppings and other debris can be removed before the interior cavity of the wall is grouted. Tie: A device for holding two parts of a construction together; a structural device that acts in tension. Quoin (pronounced “coin"): A corner reinforcing of cut stone or bricks in a masonry wall, usually done for decorative effect. Water table: The level at which the pressure of water in the soil is equal to the atmospheric pressure; effectively, the level to which groundwater will fill an excavation; a wood molding or shaped brick used to make a transition between a thicker foundation and the wall above. Guided Reading Questions Masonry History Stone and brick masonry: The strongest and most durable of pre-industrial building materials. Masonry History  Rich History  Through the mid-1800s o Primary Building Materials  Late 1800s o New Products Developed (reinf. Concrete, steel) o Ended Masonry’s Dominance  20th Century Developments o Steel Reinforced Masonry o High Strength Mortars o High Strength Masonry Units o Variety of Sizes, Colors, Textures & Coatings Masonry - Primary Uses Today  Concrete Masonry Units (CMU) o Foundation Walls

o Structural Support Walls (low rise) o Backup Walls for Exterior Facing  Brick & Stone o Facing Materials - Veneers o Decorative Walls Mortar Mortar  Cushions masonry units, ensuring uniform bearing one against the other  Seals joints between the masonry units, minimizing the flow of air and water  Adheres units, providing resistance to lateral forces from wind, earthquakes  In combination with brick, contributes to the appearance of the wall Portland Cement-Lime Mortar Ingredients: Portland cement  Primarily calcium silicates o Sources of calcium: Limestone, marble, and other minerals o Sources of silica: Clay, sand, shale, marl  Portland cement is an hydraulic cement : It hardens by chemically combining with water (hydration).  Very fine particle size: 0.0004 to 0.0006 inches diameter Portland Cement-Lime Mortar Ingredients: Aggregate  Natural sand  Manufactured sand made from crushed stone, gravel, or furnace slag  Particle size: A well-graded mix with particles ranging in size from 0.003 – 0.187 inches in diameter  Sands must be free of contaminants, physically sound, and not chemically reactive with the other mortar ingredients. Portland Cement-Lime Mortar Ingredients: Hydrated lime  Quicklime : Limestone and other minerals are finely ground and heated to produce calcium and magnesium oxides: CaO/MgO.  Hydrated lime : Sufficient water is added to quicklime to slake or chemically convert the oxides to hydroxides: Ca(OH)2/Mg(OH)2.  Hydrated lime remains a dry powder . Portland Cement-Lime Mortar Ingredients: Water  Clean , neutral pH, free of contaminants or organic material  Potable water is generally considered suitable. The Mortar Mix  Sand provides the basic structural capacity of the hardened mortar.  Cement is the glue that binds the sand particles together.  Lime improves the workability of mortar in its plastic state.  A minimum amount of water is necessary for the chemical hydration of the cement; additional water is added to produce a working consistency to the wet mortar. Blended hydraulic cement  Portland cement mixed with other cementitious materials  Replaces portland cement in cement-lime mortar mix Masonry Cement  Proprietary mortar mix of cementitious materials, lime, plasticizers, and other ingredients  No added lime  Convenience and consistent quality of pre-mixed ingredients  Good workability, and improvements in some properties of hardened mortar such as reduced drying shrinkage  Lower bond strength than cement-lime mortars

 A proprietary pre-mixed product , like masonry cement  But produced to a standard that assures higher bond strength comparable to cement-lime mortar Lime Mortar  No hydraulic cement  Cures by a chemical reaction called carbonation -atmospheric CO2, combines with the hydroxides  Has some ability to self-heal hairline cracks that may develop over time; as water and air enter the joint, carbonation can occur and repair the joint  Used primarily for the restoration of historic masonry structures Mortar Admixtures  Pigments , colored aggregate  Bond enhancers : Improve flexural strength, freeze-thaw resistance  Set accelerators and retarders : Adjust setting time in cold or hot weather  Water repellents : Improve water resistance (for concrete masonry units only)  Workability enhancers : Ease placement of wet mortar Mortar Types  Higher-strength mortars have a higher proportion of cement to lime in the mortar mix, resulting in higher compressive strength in the hardened mortar.  Higher strength mortars are more expensive and have poorer workability characteristics in comparison to lower-strength mortars.  In general, the lowest strength mortar suitable for a particular job is the optimal choice.  Type S and Type N mortars are the most commonly specified. Mortar Type Specification: Proportion Specification  Mortar types are defined by the proportion of ingredients . o Simpler and more common method of defining mortar requirements.  Note the higher lime content of lower-strength mortar types.  Note that no lime is added to mortar cement or masonry cement mixes.  Mortar types are defined by minimum strength and other properties demonstrated through laboratory testing for the proposed mix.  This specification method is most suitable to large projects, where the added cost and complexity of laboratory testing can be offset by more flexibility in selecting ingredients and proportions in the mortar mix. Brick Masonry Brick Raw Materials Preparation  Natural clays are excavated from the earth.  These raw materials are ground up and screened to control particle size.  Water is added to achieve a plastic consistency ready for molding into bricks . Brick Forming: Extruded or Stiff mud process bricks  Moderately moist clay is extruded through dies and then sliced into individual units.  Generally least expensive molding method  Accounts for approximately 90% of US made bricks  The extrusion process naturally produces brick units with a smooth face and high dimensional uniformity .  Various post-extrusion distressing steps can be used to create bricks with greater variation in shape and surface texture (right). Brick Forming: Molded bricks  Soft mud process : Relatively moist clay is pressed into individual molds o Water-struck: Molds are pre-wetted o Sand-struck: Molds are pre-dusted with sand o May be hand- or machine-pressed  Dry-press process : Low-plasticity clays are kept relatively dry and stiff, and machine-pressed into steel molds at high pressure.  Molded bricks frequently are associated with more natural variation in texture and dimensional uniformity than extruded bricks.  Molded brick costs vary with the molding process, but are frequently more expensive than extruded brick.

Brick Firing  After forming, bricks are dried and then packed into a firing kiln , where they pass through various stages of drying and chemical transformation.  Tunnel kiln (right): Brick loads pass continuously from one end of the kiln to the other.  Periodic kiln : Batches of bricks are loaded, fired, cooled, and removed.  Firing takes 10 to 40 hours .  Brick placement and firing conditions affect : o finished brick color o uniformity of shape o hardness o other physical properties Brick Sizes  Bricks are available in many sizes and standard sizes vary regionally .  Some bricks are sized so that the dimension of one brick plus one mortar joint equals a convenient nominal dimension .  Example: A modular brick combined with a mortar joint occupies 4 inches in width (3 5/8" + 3/8") and 8 inches in length (7 5/8" + 3/8"). Special Shapes and Sizes  Special or custom-shaped bricks can be used to form arches, water tables, and many other surfaces and features. Brick Classifications  Solid brick : Not less than 75% solid (in any section cut perpendicular to bearing).  Solid bricks are frequently not 100% solid, to reduce weight and the costs of firing.  Hollow brick : Up to 60% void  With hollow brick, larger sized units can be kept lighter in weight  Because of their lighter weight, hollow bricks require less energy to fire .  The larger voids in hollow brick readily accommodate steel reinforcing in reinforced brick masonry.  Facing brick : Brick with appearance characteristics graded for exposed applications.  Building brick (right): Brick intended for concealed locations where appearance is not a concern. Brick Grade  Brick Grade: Defines durability (e.g., compressive strength, absorption, freeze-thaw resistance)  Grade NW : Interior brick, concealed building brick, and other brick not exposed to the weather  Grade MW : Above grade brick only , in regions of negligible weathering (see map)  Grade SW : Any weathering region, above or below grade Brick Type  Brick Type : Defines uniformity in size and shape  Applies only to facing brick  Less uniform bricks , which may be considered more aesthetically desirable, may be more expensive than more uniform bricks.  More uniform bricks are more suitable to applications where close dimensional tolerances must be maintained , such as in a brick masonry curtain wall. Brickwork Terminology  Course: One horizontal row of bricks  Bed Joint: Horizontal joint between courses  Head Joint: Vertical joint between bricks in same course  Wythe: One vertical stack of bricks  Collar Joint: Vertical joint between wythes  Rowlock: Brick laid on its face, with end visible  Stretcher: Brick laid flat, with face visible  Header: Brick laid flat, with end visible

 Soldier: Brick laid on its end, with its face visible  Sailor: Like a soldier, but with its broader side visible Brick Bonds  Headers or rowlocks in a multi-wythe wall serve an important functional purpose, tying together the two wythes .  In a single-wythe wall , different brick bonds may be chosen purely for the visual patterns they create in the exposed face of the wall.  Running Bond : All stretchers  Common Bond : Stretcher courses, with a header row usually every 5 or 6 courses  English Bond : Alternating stretcher and header courses  Flemish Bond : Alternating stretchers and headers in each course Laying Bricks  Corner leads are constructed ahead of the rest of the wall .  Levels and string lines are used to keep the wall straight and true. Joint Tooling  Compacts joint surface to make it more durable and water-resistant.  Neatens joint appearance.  The concave joint and vee joint shed water most effectively and are the most resistant to freeze-thaw. Spanning Openings  Lintels (steel angle, stone, precast concrete, reinforced)  Arches  Corbelling Reinforced Brick Masonry (RBM)  Steel reinforcing and grouting are added to the masonry wall, to increase its strength, especially in bending and shear.  Bottom image: a two-wythe RBM panel is load tested. Additional Resources Video  Brick Masonry Techniques for Builders - Mortar: Type "N" or Type "S"  Concrete bricks making machine automatic  Brick Masonry Techniques for Builders - Full Head Joints  Brick Masonry  Bricklaying and spreading a bed joint Chapter 9 - Stone and Concrete Masonry Thought Points  Focus on the types of stone and their properties, methods of working and finishing stone, the details of conventionally set stonework, production and types of concrete masonry units, grading of concrete masonry units, and decorative CMU. Key Terms Igneous rock: Rock formed by the solidification of magma. Sedimentary rock: Rock formed from materials deposited as sediments, such as sand or sea shells, which form sandstone and limestone, respectively. Metamorphic rock: A rock created by the action of heat or pressure on a sedimentary rock or soil. Granite: Igneous rock with visible crystals of quartz and feldspar. Basalt: A dense and durable igneous rock, usually dark gray; classified by ASTM C119 in the Granite group. Limestone: A sedimentary rock consisting of calcium carbonate, magnesium carbonate, or both. Freestone: Fine-grained sedimentary rock that has no planes of cleavage or sedimentation along which it is likely to split.

Free water: In wood, water held within the cavities of the cells. See also Bound Water. Quarry sap: Excess water found in rock at the time of its quarrying. Sandstone: A sedimentary rock formed from sand; classified by ASTM C119 in the QuartzBased Dimension Stone group. Brownstone: A brownish or reddish sandstone; classified by ASTM C119 in the Quartz-Based Stone group. Bluestone: A sandstone that is gray to blue-gray and splits readily into thin slabs; classified by ASTM C119 in the QuartzBased Stone group. Slate: A metamorphic form of clay, easily split into thin sheets. Marble: A metamorphic rock formed from limestone by heat and pressure. Travertine: A richly patterned, marblelike form of limestone; classified by ASTM C119 in the Other Stone group. Dimension stone: Building stone cut to a rectangular shape. Ashlar: Squared stonework. Flagstone: Flat stones used for paving or flooring. Jet burner: A torch that burns fuel oil and compressed air, used in quarrying granite. Spalling: The cracking or flaking of the surface of concrete or masonry units, caused, for example, by freeze-thaw action, corroding reinforcing, or pointing mortars that are harder and stronger than the mortar deeper in the masonry joint. Lewis: A device for lifting a block of stone by means of friction exerted against the sides of ahole drilled in the top of the block. Guided Reading Questions Answers 1. Brick is obtained by taking rock from the earth and reducing it to the required shapes and sizes for construction. FALSE 2. Geologically, stone can be classified into four types according to how it was formed: igneous, sedimentary, moltaic, and metamorphic. FALSE 3. ASTM C119 classifies stone used in building construction into six groups: granite, limestone, quartz-based stone, slate, marble, and other. TRUE 4. More than three-quarters of the building stone used in the United States originates in domestic quarries. FALSE 5. Granite is an igneous rock made of a mosaic of mineral crystals and is nonporous, hard, and durable. TRUE 6. Basalt is one of a group of stones that may be collectively referred to as “black granites”. TRUE 7. Limestone may be found in a strongly stratified form or in deposits that are more homogenous in structure. TRUE 8. Limestone is an igneous rock mainly comprised of a mosaic of mineral crystals like feldspar and quarz. FALSE 9. Limestone must be seasoned in the air to evaporate the quarry sap to become harder and resistant to frost damage. TRUE

10. Stones in lower density classifications are generally stronger and less porous than those with higher densities. FALSE 11. Sandstone was formed in ancient times from deposits of quartz sand and will not accept a high polish. TRUE 12. Slate is a dense, hard stone with closely spaced planes of cleavage along which it easily breaks into cubes. FALSE 13. In its true geologic form, marble is a recrystallized form of limestone. TRUE 14. Many of the marbles most prized for their color and figure belong to the classification Group A. FALSE 15. The marble Group also includes other stones that can take a high polish but are not true marbles, such as dense limestones called limestone marble, onyx marble, serpentine marble, and others. TRUE 16. Fieldstone is stone that has been quarried and cut into rectangular shapes. FALSE 17. Flagstone consists of thin slabs of stone, either rectangular or irregular in outline that are used for flooring and paving. TRUE 18. The oldest method of cutting stone blocks from quarries involves chain saws and belt saws with diamond blades. FALSE 19. Granite is much harder than other stones, so it is quarried with the use of a jet burner that melts the granite down into a molten form. FALSE 20. Automated equipment is often used to cut and carve repetitive pieces of stone. TRUE 21. Common names for stone do not necessarily correspond to their geologic origins, mineral composition, or physical properties. TRUE 22. Architects and building owners have tended to select stone primarily on the basis of appearance, durability, and cost, often with minimal regard to national origin. TRUE 23. Stone masonry refers to the mortar used to lay stone blocks much like bricks FALSE 24. Rubble can take many forms, from founded, river-washed stones to broken pieces from a quarry. TRUE

25. Rubble stonework is laid very much like brickwork, except that the irregular shapes and sizes of the stones require the mason to select each stone carefully to fit the available space. TRUE 26. Both ashlar and rubble are usually laid with the quarry bed, or grain, of the stone running in the vertical direction, because the stone is both stronger and more weather-resistant in this orientation. FALSE 27. Concrete masonry can be used for concealed parts of a stone wall because it’s more easily reinforced and less expensive. TRUE 28. Mortar joins in stone masonry are frequently raked after setting the stones. TRUE 29. The primary function of the pointing mortar is aesthetic. FALSE 30. To ensure that pointing mortar does not lead to concentrated stresses at the face of the masonry, it should always be higher strength than the mortar deeper in the joint. FALSE 31. Some building stones, especially limestone and marble, deteriorate rapidly in the presence of acids. TRUE 32. Concrete masonry units (CMUs) are manufactured in three basic forms: larger hollow units, solid bricks, and, less commonly, larger solid units. TRUE 33. Heavier concrete blocks are more expensive to manufacture, but are more resistant to abuse. FALSE 34. Although concrete masonry can be formed by molds, cutting units with a diamond-bladed power saw is more economical and produces better results. FALSE 35. Concrete masonry is frequently reinforced with steel to increase its loadbearing capacity, or resistance to seismic forces and cracking. TRUE 36. Joint reinforcing is made of welded grids of small-diameter steel rods that are laid into the bed joints at set vertical intervals. TRUE 37. In most cases of reinforced vertical block cores, only those cores that do not contain reinforcement bars are grouted. FALSE

38. Lintels for concrete brick walls may be made of steel angles, combinations of rolled steel shapes, reinforced concrete, or bond beam blocks with grouted horizontal reinforcing. TRUE 39. Dry-stacked and surface-bonded masonry walls are constructed by stacking concrete masonry units in a running bond directly upon one another without the application of mortar. TRUE 40. Once the dry-stacked wall is complete, a thin layer of a special plaster containing short reinforcing fibers of alkali-resistant glass is applied to each side. TRUE 41. Decorative concrete masonry units are easily and economically manufactured in an unending variety surface patterns, textures, and colors etc. TRUE 42. Concrete blocks are more expensive on a volume basis than brick or stone blocks. FALSE 43. Concrete walls are relatively nonporous. FALSE 44. Unlike brick, concrete masonry, and stone, glass blocks are nonabsorbent. TRUE 45. When glass masonry walls are constructed, the mortar stiffens more quickly than it does with these other of materials. FALSE 46. Autoclaved aerated concrete (AAC) is made from sand, lime, water, and a small amount of aluminum powder. TRUE 47. AAC is available in solid blocks that are laid in mortar like other concrete masonry units. TRUE 48. AAC is nonporous enough to be left exposed. FALSE Uncoursed stone masonry: Stone masonry laid without continuous horizontal joints; random. Quarry bed: A plane in a building stone that was horizontal before the stone was cut from the quarry; also called grain. Grain: In wood, the direction of the longitudinal axes of the wood fibers or the figure formed by the fibers. In stone, see Quarry bed. Raked mortar joint: A mortar joint in which mortar has been removed from the portion of the joint closest to the surface of the masonry. Pointing mortar: Mortar used for the pointing of masonry joints, generally of relatively low strength and with good workability and adhesion characteristics. Concrete masonry unit (CMU): A block of hardened concrete, with or without hollow cores, designed to be laid in the same manner as a brick or stone; a concrete block. Concrete block: A concrete masonry unit, usually hollow, that is larger than a brick. Horizontal reinforcing: Steel reinforcing that runs horizontally in a masonry wall in the form of either welded grids of small-diameter metal rods or larger conventional reinforcing bars. Structural glazed facing tile: A hollow clay masonry unit with glazed faces. Structural terra cotta: Molded components, often highly ornamental, made of fired clay, designed to be used in the facades of buildings. Glass block: A hollow masonry unit made of glass. Autoclaved aerated concrete (AAC): Concrete formulated so as to contain a large percentage of gas bubbles as a result of a chemical reaction that takes place in an atmosphere of steam. Guided Reading Questions

Stone versus Brick  Similarities: o Both stacked o Mortar Joints  Differences: o Shape:  Brick molded - Stone Cut and Carved o Physical Properties:  Brick made/controlled – Stone provided by nature Stone Masonry Geologic Stone Types  Igneous: Rock developed in a molten state  Sedimentary: Rock formed from particles deposited by wind and water  Metamorphic: Formerly igneous or sedimentary rock transformed by heat and pressure Stone Classification For commercial purposes, building stone is classified into six groups according to ASTM C199. 1. Granite 2. Limestone 3. Quartz-Based 4. Slate 5. Marble 6. Other groups Granite Group  Igneous rock  Mixture of mineral crystals; principally feldspar, quartz  Nonporous, strong, durable  Suitable for exposure to severe weathering, ground contact  Many colors  Can accept many finishes, including polished Limestone Group  Sedimentary rock  Calcium carbonates (oolitic limestone) and magnesium carbonates (dolomitic limestone)  Strength and porosity vary with density  Colors from white, to gray, to red  Normally has a textured finish; only a few types can be polished Quartz-Based Stone Group  Sedimentary rock  Sandstone: from quartz deposits  Brownstone, and some varieties of bluestone are varieties of sandstone  Varies in density and porosity  Color is often light, but may vary significantly with types of materials that bind the quartz particles  Cannot be polished

Slate Group  Metamorphic rock  Derived from shales (mineral clays)  Dense, hard, nonabsorbent  Closely spaced planes of cleavage  Variety of colors Marble Group  Metamorphic rock  Recrystallized limestone  Varies greatly in its physical properties and appearance  Many colors, frequently with extensive veining  Easily polished  This group also includes other stone types that can take a high polish but are not true geologic marbles: limestone marble, onyx marble, serpentine marble, etc. Other Group  Travertine: o Partially-crystallized, patterned calcite o Chemically similar to limestone o Similar to marble in its physical properties  Alabaster  Greenstone  Schist  Serpentine  Soapstone Stone Masonry – Process Quarrying (limestone)  A long-bladed diamond saw , traveling on rails, makes deep, long cuts into the solid rock.  Closely-spaced horizontal holes are drilled into the vertical face of the rock to create a plane of weakness near the bottom of the saw cuts (not shown).  Rubber bladders are inserted into the saw kerfs and inflated, causing the large slabs to fall away from the solid rock.  Steel wedges are driven into the separated slab, to cause it to split into smaller blocks.  Blocks are labeled and stacked, ready for transporting to the mill. Milling operations  Bandsawing  Circular sawing  Hand Carving Ways to select stone  Past history can be a good predictor of future performance in similar applications and environments.  Petrographic analysis: Microscopic analysis of mineral content and structure  Laboratory Testing : Water absorption, density, compressive strength, dimensional stability, freeze-thaw resistance, chemical resistance, etc. Stone Cladding, Stone Curtain Wall  Stone panels mechanically attached to building frame  Attachment system carries the weight of the panels Stone Masonry

 Stones carry their own weight.  Most commonly set in mortar, like brick or CMU  May also be dry set , stacked without mortar, or set on shims with sealant-filled joints  Stone blocks carry gravity loads. CMU wall with anchors provides lateral support. Laid in Mortar (like bricks) or mechanically fastened in large sheets to a support system Stone Masonry Patterns Laid in Mortar  Shape o Rubble (Unsquare pieces) o Ashlar (Square Pieces)  Type of Joint o Coursed or Random  Orientation (grain horiz.) o Strength o Weather Resistance Type of Joint  Ashlar: Squared blocks  Random: Laid without continuous horizontal joints  Coursed: Laid with continuous horizontal joints Stone Masonry  Rubble: Unsquared stone blocks  Random: Laid without continuous horizontal joints  Coursed: Laid with continuous horizontal joints Concrete Masonry – CMU Manufacturing Process Concrete Masonry Units  Manufacturing Process o Stiff concrete mixture into metal molds, wet blocks are turn onto A rack  Configurations o Sizes & shapes- Solid bricks, large solid, hollow units o Weights- Lightweight to Normal  Testing Standards  Stiff concrete mix pressed into metal molds  Steam curing in autoclaves accelerates curing CMU- Sizes  Standard nominal size: 8" x 8" x 16"  Actual size is 3/8-inch less in each dimension.  Other common sizes: o 8" in length o 4", 6", 10", and 12" width Hollow Concrete Block  Most common CMU  Sizes- 8” most common

 Placement Cost o More economical to lay than brick  Reinforcing- conducive  Uses o Back up wall for brick or stone  Finishes- plaster, stucco, tile, exposed or coated CMU Weight Classifications  Lighter weight blocks o Less expensive to transport and lay o Lower thermal conductivity: higher fire-resistance rating and potentially better building envelope thermal performance  Heavier weight blocks o More durable o Higher compressive strength o Better acoustical isolation between adjacent spaces Concrete Masonry – CMU Installation Process Laying CMU  Mortar is identical to that used for brick masonry.  Corner leads are laid first.  String lines and levels are used to keep walls straight, plumb, and level.  Joints are tooled and the face of the blocks cleaned as work progresses. Concrete Masonry Reinforcing  Reinforcing increases compressive strength, resistance to cracking, and resist to lateral forces .  Vertical steel reinforcing bars in a fully-grouted concrete block wall  Horizontal joint reinforcing and vertical steel reinforcing bars  Joint reinforcing is made from wires that are small enough in diameter to fit within the mortar joint.  Horizontal reinforcing bars  A masonry saw has been used to partially cut out the webs of the blocks, making space for the bars. (The cutoffs can be seen lying on the ground to the left of the wall.)  The blocks have yet to be grouted.  Horizontal and vertical reinforcing bars  Note the blocks with specially-shaped webs that accommodate the horizontal reinforcing without modification. Spanning Openings  Structural steel  Steel reinforced concrete block lintel  Precast concrete CMU Decorative or Architectural Decorative or Architectural CMU  Easily & economical to manufactured  Variety- surface, color, texture  Uses- exterior & interior Split-face block  Two or more blocks are cast as a single unit .  During the curing process, the blocks are split with knife-like blades.  Naturally textured surfaces with exposed aggregate are created.

Ground-face block  After curing, block surface is ground smooth , creating a polished terrazzo-like surface.  In any architectural block, the color of aggregates and cement can also be varied. Other Types of Masonry Units  Glazed block, structural glazed facing tiles  Terra cotta  Glass block Additional Resources Videos  Stone Masonry  Basic of Bricklaying  Stone Masonry, Footing  Stone work Chapter 10 –Masonry Wall Construction Thought Points  Focus on details of masonry walls and their potential concerns.  Review the details of a masonry cavity walls. Key Terms Solid masonry: Masonry walls without cavities; historically, thick, monolithic masonry walls that rely primarily on their mass for their strength, durability, and tempering of the flow of heat and moisture from inside to outside. Cavity wall: A masonry wall that includes a continuous airspace between its outer most wythe and the remainder of the wall. Flashing: A thin, continuous sheet of metal, plastic, rubber, or waterproof paper used to prevent the passage of water through a joint in a wall, roof, or chimney. Weep hole: A small opening whose purpose is to permit drainage of water that accumulates inside a building component or assembly. Dampproofing: A coating intended to resist the passage of water, commonly applied to the outside face of basement walls or to the inner face of a cavity in a masonry cavity wall. Cavity drainage material: A material placed in the airspace of a cavity wall to catch mortar droppings and prevent clogging of weep holes at the bottom of the cavity. Veneer: A thin layer, sheet, or facing. Bearing wall: A wall that carries structural loads from floors, roofs, or walls above. Ordinary construction: A traditional building type with exterior masonry bearing walls and an interior structure of balloon framing. Guided Reading Questions Answe 1. Composite masonry walls are solid walls in which a single wythe is bonded to the wood structure or paneling behind it in such a way that they act as a unified mass. FALSE 2. Every masonry wall is porous to some degree. TRUE 3. Solid masonry construction relies on the wall’s mass to absorb and then gradually release moisture that enters the wall. TRUE 4. A cavity wall interposes a hollow vertical space within the wall to intercept water that penetrates the outer wythe. TRUE 5. To further protect against water penetration, dampproofing or other water resistive material is applied to the outside of the face wythe, or veneer. FALSE

6. In a loadbearing cavity wall, the backup wythe normally carries structural loads, while the outer wythe serves as a nonstructural veneer. TRUE 7. Reinforced masonry loadbearing walls can be constructed to be thinner than comparable unreinforced walls resulting in savings in materials, construction labor, and floor area taken up by the wall. TRUE 8. After a reinforced wall has been completed, but before the mortar has cured, each rod or tendon is tensioned and anchored in its taut condition. FALSE 9. Ordinary construction describes the method of using wood light frame joists and rafters for framing the floors and roof and supporting them at the perimeter on masonry walls. TRUE 10. Platform framing of the interior loadbearing partitions is used in ordinary construction instead of balloon framing because it minimizes the sloping of floors. FALSE 11. Buildings constructed of exterior masonry and interior heavy timber construction are traditionally referred to as Mill construction. TRUE 12. The traditionally recommended separation between wythes of a cavity wall is not less than 6 inches. FALSE 13. External masonry flashings are used to catch water that has entered the wall and drain it through weep holes back to the exterior. FALSE 14. The metal coping at the top of a masonry parapet is one example of an external flashing. TRUE 15. Flashing at the intersection of a flat roof and a wall parapet is usually constructed in two overlapping parts: a base flashing that is part of the roof membrane and an external metal counterflashing. TRUE 16. Sheet metal flashings are the least expensive and least durable flashings. FALSE 17. Aluminum is unsuitable for flashings in masonry walls because it reacts chemically with mortar. TRUE 18. At corners and other junctions where sections of flashing material meet, the pieces should be lapped and soldered or sealed with a suitable mastic. TRUE 19. Cavity wall vents are similar to weeps but located to the top of the wall cavity. TRUE 20. A solid masonry wall is an efficient insulator. FALSE

21. Exterior insulation and finish system (EIFS) consists of panels of plastic foam that are attached to the masonry and covered with a thin, continuous layer of polymeric stucco reinforced with glass fiber mesh. TRUE 22. Masonry walls do not expand or contract in response to changes in temperature and moisture content. FALSE 23. New concrete masonry units usually shrink somewhat as they give off excess water following manufacture. TRUE 24. Control joints are intentionally created planes of weakness that can be open to accommodate shrinkage in masonry surfaces, usually during initial curing. TRUE 25. Isolation joints are placed at junctions between masonry and other materials to accommodate differences in movement between these materials. TRUE 26. Settlement joints are used to divide a geometrically complex building into smaller units that can move independently of one another during an earthquake. FALSE 27. Efflorescence is a hard, grey mortar byproduct that sometimes appears on the surface of brick, stone, or concrete masonry. FALSE 28. Efflorescence consists of one or more water-soluble salts that were originally present either in the masonry units or in the mortar. TRUE 29. Mortar joints are the weakest link in most masonry walls. TRUE 30. Repointing is a process of raking and cutting out defective mortar and replacing it with fresh mortar. TRUE 31. Most masonry materials, including mortar, are nonporous and prevent the conduction of water from one side of the wall to the other. FALSE 32. Integral water repellents may be added to the mortar when exterior walls are constructed of solid masonry. TRUE 33. Mortar cannot be allowed to freeze after it has cured; otherwise, its strength and watertightness may be seriously impaired. FALSE 34. Permeable unit paving systems allow rainwater to pass through the paving system and infiltrate the soil beneath. TRUE

35. Walls made of masonry are naturally effective and durable barriers to the passage of fire, making them well suited for use as fire walls and other types of fire-resistant separations within and between buildings. TRUE 36. Due to their hard surfaces, masonry walls are ineffective in limited the transmission of sound from one space to another. FALSE Heavy Timber Construction: A type of wood construction made from large wood members and solid timber decking in a post-and-beam configuration; in the International Building Code, buildings of Type IV HT construction, consisting of heavy timber interior construction and noncombustible exterior walls, which are considered to have moderate fire-resistive properties. External flashing: In masonry, a flashing that is not concealed within the wall, usually at the roof level or top of the wall. Internal flashing: In masonry, a flashing concealed with the masonry; also called a concealed or through-wall flashing. Base flashing: The flashing at the edges of a low-slope roof membrane that turns up against the adjacent face of a parapet or wall; frequently overlapped by a counterflashing. Counterflashing: A lashing turned down from above to overlap another flashing turned up from below so as to shed water. Reglet: A slot, usually horizontal, and inclined in cross section, into which a flashing or roof membrane may be inserted in a concrete or masonry surface. Self-adhered flashing: A flexible, self-sticking flashing material, usually made of polymermodified asphalt laminated to a plastic backing, with preapplied adhesive on one side. End dam: The turned-up end of a slashing that prevents water from running out of the end; a block inserted into the space within a horizontal aluminum mullion for the same purpose. Exterior insulation and finish system (EIFS): A cladding system that consists of a thin layer of reinforced stucco applied directly to the surface of an insulating plastic foam board. Furring strip: A length of wood or metal attached to a masonry or concrete wall to permit the attachment of finish materials using screws or nails; any linear material used to create a spatial separation between a finish material and an underlying substrate. Nonmovement joint: A connection between materials or elements that is not designed to allow movement between the parts. Movement joint: A line or plane along which movement is allowed to take place in a building or a surface of a building in response to such forces as moisture expansion and contraction, thermal expansion and contraction, foundation settling, and seismic forces. Working joint: A connection that is designed to allow small amounts of relative movement between two pieces of a building assembly. Structure/enclosure joint: A connection designed to allow the structure of a building and its cladding or partitions to move independently. Isolation joint: A type of joint used to separate abutting materials or assemblies that should remain structurally independent, such as where new construction meets old, or where a nonstructural slab on grade abuts structural columns or walls. Control joint: An intentional, linear discontinuity in a structure or component designed to form a plane of weakness where cracking can occur in response to various forces so as to minimize or eliminate cracking elsewhere. Also called a contraction joint. Expansion joint: A seam within a material or between materials that provides for material expansion and contraction. Building separation joint: A plane along which a building is divided into separate structures that may move independently of one another. Volume-change joint: A building separation joint that allows for expansion and contraction of adjacent portions of a building without distress. Settlement joint: A building separation joint that allows the foundations of adjacent building masses to settle at different rates. Efflorescence: A light-colored, powdery deposit on the face of masonry or concrete, caused by the leaching of chemical salts from water migrating from within the structure to the surface. Spalling: The cracking or flaking of the surface of concrete or masonry units, caused, for example, by freeze-thaw action, corroding reinforcing, or pointing mortars that are harder and stronger than the mortar deeper in the masonry joint. Repointing: The process of removing deteriorated mortar from the zone near the surface of a brick wall and inserting fresh mortar. Tuckpointing: Traditionally, a method of finishing masonry joints using mortars of different colors to artificially create the appearance of a more refined joint; in contemporary usage, may be used interchangeably with repointing. Guided Reading Questions Types of Masonry Walls Composite Masonry Walls  Multiwythe

o Outer wythe of stone, face brick, or other durable masonry material o Inner wythes of less expensive CMU or clay units which do not require the same level of durability or finish appearance  Solid--no internal cavity o Space between wythes is filled with mortar  Wythes are bonded with: o Header units (in traditional construction) o Metal ties or reinforcing (right)  Most commonly associated with traditional or historic masonry wall construction Masonry Cavity Walls  Greater resistance to water penetration than solid or composite walls  Multiwythe  A continuous air space between wythes acts as an internal drainage plane.  Water that penetrates the outer wythe runs down the cavity and then is drained back to the exterior.  Wall ties or veneer ties , made of corrosion resistant metal , span the cavity and allow the inner wythe to provide lateral support to the, usually thinner, outer wythe. o Stainless steel: longest lasting o Galvanized (zinc-coated) steel: less expensive  Wall ties come in a great variety of configurations . In this illustration the ties also serve to hold rigid insulation boards snugly against the inner wythe.  Flashings: Continuous waterproof membranes that intercept water in the cavity and redirect it to the exterior  Weep holes : Allow water to drain out from wall  Dampproofing : Water-repellent coatings applied to the face of the inner wythe to provide additional resistance to water penetration  The mastic air barrier also serves as the water-repellent coating.  The minimum recommended cavity depth is 2 inches , to allow space for masons to keep the cavity clear of mortar droppings during construction.  Water-resistant rigid insulation boards can be inserted into the cavity. But a minimum of 1 inch of clear airspace should be preserved.  Cavity drainage materials : Materials inserted into the cavity to catch mortar droppings and prevent obstruction of weep holes  Mortar droppings should always be minimized, as they form bridges across the cavity that can allow water to bridge the cavity as well.  Cavity drainage materials : Materials inserted into the cavity to catch mortar droppings and prevent obstruction of weep holes  Mortar droppings should always be minimized, as they form bridges across the cavity that can allow water to bridge the cavity as well. Masonry Loadbearing Walls  Carry gravity loads from other parts of the building structure (adjacent floors and roof)  In modern construction, almost always reinforced o Greater strength o Much improved resistance to seismic forces  May be composite or cavity wall construction o In loadbearing cavity walls, the inner wythe is usually the loadbearing wythe and the outer wythe or veneer is nonstructural. Spanning Systems For Masonry Bearing Wall Construction Ordinary Construction  Light wood frame interior structure, with noncombustible masonry exterior walls Mill Construction  Heavy timber interior structure , with noncombustible masonry exterior walls  Mill construction is considered more fire-resistant than ordinary construction because the heavy timbers are slower burning than the thinner framing members of ordinary construction. Steel and Concrete Decks with Masonry Bearing Walls  Open-web steel joists, corrugated steel decking, and concrete floor slabs with masonry bearing walls

 OWSJs are well suited to masonry loadbearing construction because of their relatively close spacing which imposes a more uniform load on the masonry wall .  With structural steel framing at greater spacings, extra reinforcing or enlarged masonry piers may be required to carry the greater concentrated loads at bearing points.  Precast concrete hollow core slabs with cast-in-place concrete topping  The wall in this example is single-wythe, fully grouted, reinforced CMU bearing wall . Traditional Masonry Loadbearing Wall Construction  Light wood joists bearing on a traditional solid brick masonry wall.  Traditional masonry structures are under-reinforced by contemporary standards and often must be structurally upgraded.  Steel straps and perimeter steel angles tie the floor to the exterior wall to improve the building's ability to transfer seismic loads from the unreinforced masonry walls, to the structural frame.  The floors and roofs are tied to new, structural steel framing that is strategically inserted into the building and which can carry the seismic loads securely to the foundation. Detailing Masonry Walls Flashings and Drainage  Flashings are built into masonry walls to intercept water that penetrates the wall and direct the water back to the exterior .  Common materials include various metals, synthetic rubber or bituminous membranes, and plastics .  Materials should be chosen with longevity in mind— internal flashings must last as long as the wall. Flashings and Drainage: Metal Flashings  Most expensive and most durable  Stainless steel o Long-lasting o Non-staining o Stiffer and harder to form than copper  Copper ( middle ) o Long-lasting o Runoff from flashing can cause staining by copper oxides o Softer and more easily formed than stainless steel  Galvanized (zinc-coated) steel o Less expensive o Less durable o Not recommended for permanent internal flashings o OK for external, replaceable flashings  Aluminum o Not recommended for masonry walls because this metal reacts chemically with the highly alkaline mortar Flashings and Drainage: Membrane Flashings  Self-adhering bituminous membranes (right) o Polymer-modified bitumens laminated to plastic backings o Self-sticking to substrate o Less expensive and easier to install than metal flashings o Have some capacity to self-seal around penetrations o Cannot span cavities or other significant gaps without backup metal support  EPDM (Ethylene Propylene Diene Monomer ) o Synthetic rubber

o Long-lasting o Easy to install  Other plastics o May be vulnerable to tearing or other deterioration  Membrane flashings cannot be permanently exposed to sunlight . They are often combined with metal where flashings must project from the wall. Flashings and Drainage: Composite Flashings  Copper or other metals laminated with heavy paper, plastic film, or other materials  Material costs are less than all-metal flashings because the thinner metal sheets are used .  The laminating layers provide added strength, compensating for the thinner sheet metal.  Copper laminated with asphalt-saturated glass fabric Flashings and Drainage: Joining and Sealing Flashings  Where flashing sections meet, the joints must be made watertight .  Metals are most permanently joined and sealed by soldering or welding . Sealing with mastics is less expensive, but also less permanent.  Membrane and composite flashings are sealed with mastics (right) or adhesive sealants .  Self-adhering flashings are lapped and self-adhered to form a watertight seal. Flashings and Drainage: Flashing Locations  A through-wall (internal) flashing installed underneath the top-of-wall coping units intercepts water that passes between joints of those units.  An external flashing , in this case a counterflashing, is installed on the back of the parapet to prevent water from passing behind and under the roof membrane termination.  Through-wall flashings should be installed at all interruptions in the cavity .  A flashing above a wall opening intercepts water in the cavity and prevents it from spilling into the opening.  A flashing below a wall opening intercepts water that enters around the opening and keeps it out of the wall.  Where a metal angle provides support to the exterior brick wythe, a flashing on top of the angle intercepts water in the cavity .  The angle itself is not sufficiently watertight around its back and at its ends to act as a flashing on its own. The flashing also protects the angle from exposure to water and corrosion.  A flashing at the base of the wall intercepts water in the cavity.  Flashings are also used in composite walls, to intercept water that infiltrates the wall. Flashings and Drainage: Flashing Details  The backs of flashings are turned up to direct captured water toward the exterior of the wall .  Flashing ends are turned up and folded to form end dams which prevent water from spilling off the ends of the flashing into the cavity.  Flashings under windows and doors are often called sill pans .  Best practice: Flashings should project beyond the face of the wall at least ¾-inch and angle downward , so that water intercepted by the flashing falls free of the wall and does not cling to the underside of the flashing and seep back into the wall.  The exposed, projecting end of the flashing must be metal . Membranes and composite materials are not stiff enough and many degrade under exposure to sun light. Flashings and Drainage: Weeps  A short length of rope has been inserted into the head joint between masonry units to form a weep.  In some cases, the rope will remain in the joint after the wall is completed, acting as a wick to draw water pooled on the flashing out of the cavity.  In other cases, the rope is removed after the mortar has hardened, leaving a small opening.  Weeps formed with a small-diameter plastic tube and a pre-formed plastic insert.  Also below, the bituminous flashing membrane is creeping out from between the masonry bed joint. A better practice is to finish flashings with stiff metal edges that can protrude neatly from the wall. Thermal Insulation  Rigid foam , part of an Exterior Insulation and Finish System (EIFS), can be applied to the exterior side of a masonry wall .  With exterior insulation, the thermal mass of the masonry is coupled to the interior conditioned environment, and can contribute to energy savings in some circumstances.  Rigid foam insulation can be inserted into the masonry wall cavity .  CMU cores can be insulated with loose granular insulation or rigid foam inserts.  The effectiveness of insulation in CMU cores is limited by thermal bridging of the solid portions of the CMUs, and by the absence of insulation in cells where reinforcing and grouting is required.

 Proprietary CMUs with special foam inserts can improve energy efficiency by reducing thermal bridging.  A variety of types of insulation can be applied to the inner side of the wall .  Rigid foam boards being fastened to the interior side of a CMU wall using a proprietary furring system Special Problems in Masonry Construction Expansion and Contraction  Masonry construction expands and contracts due to changes in temperature, moisture content, and structural loading .  Joints must be provided to allow movement to occur without causing unsightly or detrimental cracking: o Where changes in geometry create stress concentrations o Close to corners o At intervals no greater than 125' in straight walls o At changes in support conditions  Joints are sealed at the surface of the wall , for appearance considerations and to prevent the uncontrolled passage of air and water.  Some joint designs restrict out-of-plane movement between adjacent wall sections while permitting expansion and contraction in the plane of the wall.  Vertical expansion joints in brick veneer on either side of stacked window openings  A flexible sealant material that can expand and contract with movement is applied to the joint .  Sealant color can be chosen to match that of the mortar and sand can be cast into the surface of the sealant before it cures, to imitate the appearance of a mortar joint.  Brick expands slightly over time as it absorbs moisture from the atmosphere.  Many structural systems, especially those of concrete, shrink slightly over time due to long term effects of structural loads .  On multistory buildings, horizontal expansion joints must be provided in brick veneer to allow gradual expansion of the brick.  If these joints are omitted, the veneer will gradually become compressed, bow outward, and eventually fail.  The thin, horizontal white lines are expansion joints in the brick veneer located approximately level with the floor structure behind from which the veneer is supported.  A close-up of one of the expansion joints in the last image  Note the weep hole .  This joint does not follow best practices : o The internal flashing does not project beyond the face of the wall . o The joint is not wide enough to accommodate significant movement in the veneer without risking failure of the sealant joint or overstressing of the veneer.  Horizontal and vertical expansion joints are provided where changes in the supporting structure are likely to cause differential movements in the veneer. Efflorescence  White crystalline deposits occur on the surface of masonry when moisture within carries salts from the mortar or masonry units to the surface and then evaporates , leaving the salts behind.  Efflorescence is most common with new masonry and usually decreases over time.  It can be minimized by avoiding contaminants in the masonry ingredients, and by keeping water out of the wall both during and after construction. Mortar Joint Deterioration  Water and freeze/thaw action deteriorate mortar joints over time .  Repointing : Deteriorated mortar is cut out and the joints are refinished with fresh mortar.  Care must be exercised that the new mortar is not harder or more brittle than the mortar in the remainder of the joint, or early mortar failure or damage to the bricks themselves can result. Moisture Resistance of Masonry  Cavity wall construction limits water passage through masonry walls.  Various water repellent coatings , either clear or opaque, can be applied to the wall surface. But coatings should be breathable to allow moisture that does infiltrate the wall to escape .  Mortar and concrete for CMUs can be mixed with additives that increase their water repellency . Cold and Hot Weather Construction  Mortar must not freeze while it is curing : o Keep materials dry. o Preheat materials.

o Protect construction from weather and wind. o Use cement types that cure rapidly and generate more heat while curing. o Provide temporary space heating.  In especially hot weather, mortar should be protected from water loss : o Keep mortar in shade to prevent rapid water evaporation. o Pre-wet masonry units to prevent excessive water absorption. MODULE 4 Table of contents  Weekly Readings  Chapter 3 Wood and Wood Products o Key Terms o Guided Reading Questions o Trees o Lumber o Wood Products o Wood Fasteners o Manufactured Wood Products o Additional Resources  Chapter 4 - Heavy Timber Frame Construction o Key Terms o Guided Reading Questions o Heavy Timber Frame Construction o Fire-Resistive Heavy Timber Construction o Connections o Longer Spans in Heavy Timber o Additional Resources  Chapter 5 - Wood Light Frame Construction o Key Terms o Guided Reading Questions o Wood Light Frame Construction o Foundations for Light Frame Structures o Building the Frame

o Light Wood Framing & the Building Codes o Additional Resources Weekly Readings This week you will read chapters 3, 4, and 5. Chapter 3 Wood and Wood Products Focus on the basics of wood and types of wood products used in construction. Key Terms Cambium : The thin layer beneath the bark of a tree that manufactures cells of wood and bark. Sapwood : The living wood in the outer region of a tree trunk or branch. Heartwood : The dead wood cells in the center region of a tree trunk. Cellulose : A complex polymeric carbohydrate of which the structural fibers in wood are composed. Lignin : The natural cementing substance that binds together the cellulose in wood. Grain : In wood, the direction of the longitudinal axes of the wood fibers or the figure formed by the fibers. In stone, see Quarry bed (A plane in a building stone that was horizontal before the stone was cut from the quarry; also called grain). Springwood : In wood, the portion of the growth ring comprised of relatively larger, less dense cells; also called earlywood. Plainsawn lumber : Lumber sawn in such a way that significant portions of the growth rings are oriented roughly flat relative to the board's broader face. Softwood : Wood from coniferous (evergreen) trees. Quartersawn lumber : For softwoods, lumber sawn in such a way that growth rings are aligned at an angle of approximately 45 degrees or steeper relative to the board's broader face. For hardwoods, sawn such that the growth rings are aligned at an angle of approximately 60 degrees or steeper to the broader face. Tracheid : The longitudinal cells in a softwood. Ray : A tubular cell that runs radially in a tree trunk. Bottom plate : See Sole plate. Bound water in wood, the water held within the cellulose of the cell walls. See also Free water. Equilibrium moisture content (EMC) : The moisture content at which wood stabilizes after a period of time in its destination environment. Seasoning : The drying of wood, to bring its moisture content into equilibrium with ambient conditions. Longitudinal shrinkage : In wood, shrinkage along the length of the log. Radial shrinkage : In wood, shrinkage perpendicular to the growth rings. Tangential shrinkage : In wood, shrinkage along the circumference of the log. Knot : A growth characteristic in wood, occurring where a branch joined the trunk of the tree from which the wood was sawed. Cup : A curl in the cross section of a board or timber caused by unequal shrinkage or expansion between one side of the board and the other. Wane : An irregular rounding of a long edge of a piece of dimension lumber caused by cutting the lumber from too near the outside surface of the log. Visual grading : The grading of wood for its structural properties, based on visual inspection, as distinct from machine grading; not to be confused with appearance grading. Machine grading : The grading of wood for its structural properties, performed by automated machinery, as distinct from visual grading. Appearance grading : The grading of wood for its appearance, as distinct from its structural properties; not to be confused with visual grading. Nominal dimension : An approximate dimension assigned to a piece of material as a convenience in describing its size, as distinct from its actual dimension. Actual dimension : The true dimension of a material, as distinct from its nominal dimension. Board foot : A unit of lumber volume, nominally 12 square inches in cross sectional area and 1 foot long. Board siding : Wood cladding made up of boards, as differentiated from shingles or manufactured wood panels. Dimension lumber : Lengths of wood, rectangular in cross section, sawed directly from the log. Timber : Standing trees; a large piece of dimension lumber. Veneer : A thin layer, sheet, or facing. Rotary-sliced veneer : A thin sheet of wood produced by rotating a log against a long, sharp knife blade in a lathe. Sliced veneer : Thin sheets of wood produced by pressing a knife against a log. Sawn veneer : Thin sheets of wood produced by sawing, rather than slicing with a knife blade. Plainsliced veneer : Veneer sliced from a log without regard to the direction of the annual rings, as distinct from quartersliced. Quartersliced veneer : Veneer sliced in such a way that the annual rings appear closely spaced and run roughly perpendicular to the face of each veneer. Flitch : A collection of solid wood members or veneers, all cut from a single log. Glue-laminated wood : A wood member made up of a large number of small strips of wood glued together.

Glulam : A shorthand expression for glue-laminated wood. Cross-laminated timber (CLT) : Structural panels fabricated from solid lumber pieces, with members in each layer alternating in orientation from those above and below; used as structural floor, wall, and roof elements. Structural composite lumber : Substitutes for solid lumber made from wood veneers or wood fiber strands and glue; also called engineered lumber. Laminated strand lumber (LSL) : Wood members made up of long shreds of wood fiberjoined with a binder. Oriented strand lumber (OSL) : Structural composite lumber made from shredded wood strands, coated with adhesive, and pressed into a rectangular cross section. Laminated veneer lumber (LVL) : Structural composite lumber made up of thin wood veneers joined with glue. Parallel strand lumber (PSL) : Structural composite lumber made of wood shreds oriented parallel to the long axis of each piece and bonded together with adhesive. Structural finger jointed lumber I-joist : A manufactured wood framing member whose cross-sectional shape resembles the letter I. Wood-plastic composite (WPC) : Wood-like products made from wood fibers, plastics of various types, and other additives, with a plastic content not exceeding 50 percent. Cantilever : A beam, truss, or slab that extends beyond its last point of support. Plastic lumber : Lumber-like products with a plastic content of 50 percent or more. Structural-grade plastic lumber (SGPL) : Lumber-like plastic members, reinforced with glass fibers, and formulated to be roughly as strong as conventional solid wood. Plywood : A wood panel composed of an odd number of layers of wood veneer bonded together under pressure. Oriented strand board (OSB) : A building panel composed of long shreds of wood fiber oriented in specific directions and bonded together under pressure. Particleboard : A building panel composed of small particles of wood bonded together under pressure. Guided Reading Questions Answers 1. Softwoods come from coniferous trees and hardwoods from broadleafed trees. TRUE 2. Despite their names, softwoods are usually more dense and harder than hardwoods. FALSE 3. Generally, softwoods have a relatively coarse and plain grain figure, whereas hardwoods show finer, more attractive patterns. TRUE 4. Most lumber used today for the building structural frame comes from hardwoods, which are comparatively plentiful and inexpensive. FALSE 5. Environmentally certified wood comes from forests that are managed according to the guidelines of one of several organizations that set standards for long-term ecology sustainability, resource conservation, and other considerations. TRUE 6. The Forest Stewardship Council (FSC) certification program ensures responsible forest management practices that prevent overharvesting, maintain biological diversity, conserve natural resources, and protect the environment. TRUE 7. The trees, ground litter, and soil of the Earth’s forests are responsible for storing tens of billions of tons of sequestered carbon. TRUE 8. Because trees are responsible for sequestering so much carbon, deforestation emits very moderate levels of carbon dioxide. FALSE 9. Carbon accounts for roughly 1% of the weight of dry wood. FALSE 10. When lumber is extracted from the forest and placed into use in buildings, its carbon remains stored within it. TRUE 11. Wood construction helps to mitigate climate change by acting as a large carbon sink. TRUE 12. The value of carbon sequestration should be counted regardless of whether the forest of origin is managed sustainably. FALSE

13. The beneficial impact of sequestered carbon may be part of a cradle-to-grave analysis, unlike a cradle-to-gate analysis, because it can also account for the potential return of carbon to the atmosphere under various material reuse or disposal scenarios. TRUE 14. The round logs transported after the felling of trees are called lumber. FALSE 15. Roundwood is a straight, cylindrical, longitudinal cut of lumber that may be finished or unfinished. FALSE 16. Plainsawn lumber produces the maximum yield of useful pieces, making it the most economical sawing method. TRUE 17. Quartersawing produces more waste and smaller pieces relative to plainsawn, but produces more dimensionally stable and more visually pleasing grain figures. TRUE 18. Quartersawn softwood lumber is used for flooring, trim, siding, and other types of finish woodwork, where its advantages justify the added expense. TRUE 19. Plainsawn lumber may also be referred to as vertical-grain lumber, and quartersawn may also be referred to as flat-grain. FALSE 20. Moisture content is described as the percentage of water needed to keep a sample of wood alive. FALSE 21. Water stored within cell cavities is called free water, and its evaporation has little effect on the physical properties of the wood, other than to lighten it. TRUE 22. Bound water describes the sum of free water and natural moisture content in wood. FALSE 23. Reduction in moisture content below the fiber saturation point have significant effects on the mechanical properties of wood, causing it to shrink and lose strength and stiffness. FALSE 24. Equilibrium moisture content describes the final moisture condition of wood at equilibrium with its ambient surroundings. TRUE 25. The extent of drying necessary for lumber varies on the application and is called seasoning. TRUE 26. Most lumber is seasoned on site. FALSE 27. Air drying is preferred to kiln drying because it’s cheaper and produces lumber with fewer distortions and more uniform quality. FALSE 28. Larger-dimension timbers, which are very slow to dry, are frequently allowed to complete their seasoning in their final place. TRUE 29. Wood typically shrinks and swells uniformly. FALSE 30. If an entire log is seasoned before sawing, the difference between the tangential and radial shrinkage will cause it to check, or split open along its length. TRUE

31. When lumber is sawn from the log, its position in the log determines in large part how it will distort as it dries. TRUE 32. Lumber used in building construction is normally surfaced by planes to make it smooth, more dimensionally precise, and safer to handle. TRUE 33. Planking for temporary scaffolding benefits from surfaced lumber because it’s less slippery when wet and slightly stronger and stiffer than unsurfaced planks. FALSE 34. The designation S-DRY on a lumber grade stamp indicates that it was surfaced before it was seasoned. FALSE 35. Growth characteristics are discontinuities in the structure of lumber caused by the tree it comes from. TRUE 36. Knots, knotholes, decay, and insect damage are all examples of defects called manufacturing characteristics. FALSE 37. Knots and knotholes improve the strength of a piece of lumber, but make it more difficult to cut and shape. FALSE 38. Manufacturing characteristics arise largely from changes that take place during the seasoning process because of the differences in rates of shrinkage with varying orientations to the grain. TRUE 39. Wane is a manufacturing characteristic described as irregular rounding of edges or faces that is caused by sawing pieces too close to the perimeter of the log. TRUE 40. Badly bowed wall studs, floor joists, or roof rafters may be straightened by sawing or planning away the crown before being covered by wallboard, subflooring, or sheathing. TRUE 41. Machine stress rated (MSR) lumber, machine evaluated lumber (MEL), and E-rated lumber are all visual grading processes. FALSE 42. The intermingling of similar species within one group risks an inflation in harvesting, production, and distribution costs. FALSE 43. Lumber sizes in North America are given as nominal sizes in inches describing the dimensions of the lumber after sawing and seasoning are complete. FALSE 44. Wood produced in very thin sheets is called veneer. TRUE 45. The log from which veneer is taken is called a flitch. TRUE 46. Veneers that are sequenced come from a single flitch and are arranged in the finished work in the same order they came from the log. TRUE 47. End joints between individual pieces of lumber are finger jointed or scarf jointed and glued to create structural continuity from one piece to the next. TRUE 48. Glue-laminated wood, also called glulam, are large wood structural members produced by gluing large, unsawn pieces of softwood lumber. FALSE

49. The end pieces of glue-laminated wood members are finger jointed or scarf jointed and glued to create structural continuity from one piece to the next. TRUE 50. Hybrid glulam beams substitute laminated veneer lumber to increase stiffness and strength. TRUE 51. Cross-laminated timbers (CLTs) are hollow panels laminated from thin boards of lumber, with the orientation of members alternating between layers. FALSE 52. Lumber used in the manufacture of cross-laminated timber panels is seasoned to a 12 percent moisture content, a relatively low value that helps to minimize dimensional changes and checking in the finished panels. TRUE 53. Compared to CLTs and large solid timbers, glulams are less subject to change in size with changes in moisture content due to the drier lumber used in their manufacturing. FALSE 54. Mass plywood panels are laminated with wood veneers instead of dimension lumber like CLTs. TRUE 55. Nail-laminated timber (NLT) is also called mechanically laminated timber. TRUE 56. Dowel-laminated timber (DLT) are fastened with hardwood dowels seasoned to a higher moisture content than the laminating lumber. FALSE 57. The moisture content in the hardwood dowels used to fasten DLTs cause them to swell and form a tight fit. TRUE 58. Laminated strand lumber and oriented strand lumber are made from shredded wood strands, coated with adhesive, pressed into a rectangular cross section, and cured under heat and pressure. TRUE 59. Laminated veneer lumber is made from shredded wood strands, coated with adhesive, pressed into a rectangular cross section, and cured under heat and pressure. FALSE 60. Floors framed with I-joists are sometimes more prone to uncomfortable vibration when subjected to normal occupant loads. TRUE 61. Finger-jointed wood is straighter, more stable, and more consistently free of defects than conventional sawn lumber. TRUE 62. Wood-plastic composite (WPC) are made from blends of plastic and half its weight in sawdust to provide the pigment and strength. FALSE 63. Composite wood trim is used widely for its minimal expansion and contraction related to the temperature compared to other wood products. FALSE 64. Structural-grade plastic lumber (SGPL) can be formulated to be stronger and stiffer than solid wood, as well as less prone to long-term creep under permanent loads. FALSE 65. Panels are more nearly equal in strength in their two principle directions than solid wood. Shrinking, swelling, checking, and splitting are greatly reduced. TRUE

66. Panel products make more efficient use of forest resources than solid wood products through less wasteful ways of reducing logs to building projects and thorough utilization of material that would otherwise be thrown away. TRUE 67. Composite panels are made from various formulations of reconstituted wood fiber materials. FALSE 68. Oriented Strand Board is made of long strands of wood, oriented in the same manner in each layer as the grains of veneer layers in plywood, compressed and glued into three to five layers. TRUE 69. Particleboard is manufactured in different density ranges and is made up of smaller wood particles than OSB that are compressed and bonded into panels. TRUE 70. Fiberboard is manufactured in different density ranges and is made up of smaller wood particles than OSB that are compressed and bonded into panels. It is mainly used as a base material for wood veneer and plastic laminate. FALSE 71. Panels intended for subfloors and floor underlayment are lightly touch sanded to produce a flatter, smoother surface. TRUE 72. Where an especially smooth and durable surface is required, plywood may be finished with a resin-treated overlay to make a medium-density overlay or high-density overlay panel. TRUE 73. Overlay panels are often used for their increased strength and stiffness in scaffolding and support structures where the appearance of the panels is not important. FALSE 74. The purpose of the span rating system used for wood panels is to permit the use of different types of panels while achieving the same structural objectives. TRUE 75. When specifying panels by thickness, industry standards refer to measured thickness of each individual panel, called performance category. FALSE 76. Structural wood panels fall under two bond classifications: Exterior or Exposure 1. TRUE 77. Hardboard is a thin, light panel made of lightly compressed wood fibers. It is available in various thicknesses and surface finishes, and in some formulations is durable against weather exposure. FALSE 78. Insulating fiberboard sheathing is a low-density panel, usually ½ or ¾ inch thick, made of wood or vegetable fibers and binders, and coated with asphalt for water resistance. TRUE 79. Insulating fiberboard sheathings are panels made from finely processed recycled paper waste and are used for wall sheathing, acoustical isolation, carpet underlayment, and even structural roof decking. FALSE 80. Agrifiber or biocomposite panels are made from agricultural waste products, such as the stalks or chaff of wheat, rice, hemp, sorghum, and other crop residues that are otherwise usually disposed of as solid waste or by open-air burning. TRUE 81. Biodeterioration occurs after wood is harvested, losing its natural protections and becoming vulnerable to biological attack. TRUE

82. The four necessary conditions for fungal growth are oxygen, a suitable temperature range, moisture, and direct sunlight. FALSE 83. For fungi to flourish, the wood moisture content must be lower than its fiber-saturation point. FALSE 84. The lack of available oxygen when wood is entirely submerged in water or buried in the earth below the water table accounts for the massive rate of decay in these environments. FALSE 85. Wood submerged in brackish or salt waters is vulnerable to a variety of marine-boring organisms. TRUE 86. Preservative-treated wood is impregnated with chemicals that are toxic to the biological organisms that attack the wood. TRUE 87. Pressure impregnation causes the wood’s fibers to contract enough to prevent boring organisms like termites from boring through the wood. FALSE 88. Incising the surface of wood improves the penetration of preservative materials into the wood member without affecting the member’s structural capacity. FALSE 89. Preservative treatments are always applied before drying the wood, as the moisture content tends to significantly rise. FALSE 90. Acetic anhydride makes wood more resistant to attack and decay by changing the cell walls of the wood to make it less absorptive of water. TRUE 91. Glass infused wood is made by introducing liquid sodium silicate under pressure into the wood, encasing the wood fibers in amorphous glass. TRUE 92. The heartwood of some species of wood is naturally resistant to decay and insects and can often be used where preservative-treated wood would otherwise be required. TRUE 93. Fire-retardant treatments (FRTs) are accomplished by introducing liquid sodium silicate under pressure into the wood, encasing the wood fibers in amorphous glass. FALSE 94. Nails are the favored means of fastening wood because they are inexpensive, require no predrilling of holes under most conditions, and can be installed rapidly. TRUE 95. Nails for use in structural connections are specified by the conventional name and penny size rather than actual length and shaft diameter to avoid confusion. FALSE 96. The three methods of fastening nails are called face nailing, end nailing, and toe nailing. TRUE 97. Corrosion-resistant nails are sometimes required when fastening wood members that have been chemically treated for resistance to decay or fire. TRUE 98. Modified-head fasteners fire from nail guns less reliably and with more frequent gun jams or bent fasteners than common nails. FALSE

99. In comparison to nails, screws are less expensive and quicker to install. FALSE 100. Traditional wood screws require predrilled pilot holes into which the screw is inserted and then tightened with a screwdriver. TRUE 101. Self-drilling wood screws can be quickly installed with power drivers, but still require pilot holes. FALSE 102. Bolts are used mainly for structural connections in heavy timber framing and in wood light framing for fastening ledgers, beams, or other heavy applications. TRUE 103. Washers are used to distribute the clamping force from a bolt across a greater area of wood and reduce crushing of the wood fibers. TRUE 104. A split-ring connecter is clamped around the outside of two or more pieces of wood held together with a central bolt. FALSE 105. Timber rivet connections are inserted in matching circular grooves to mate pieces of wood clamped together with a central bolt. FALSE 106. Joist hangers are used to make strong connections in floor framing wherever wood floor and roof framing members bear on one another at right angles. TRUE 107. Structural wood adhesives form bonds that are at least as strong, stiff, and durable as the members they connect. TRUE 108. Wood adhesives are used more often on construction sites due to their inexpensiveness. FALSE 109. Prefabricated wood components eliminate weather-related delays and produce components that are structurally efficient, precise in dimension, and consistent in quality. TRUE 110. Truss manufacturers use a preengineered design for specified trusses or custom engineers a truss design and develops the necessary cutting patterns for its constituent parts. TRUE 111. Framed panels are simple sections of conventional dimension lumber framing, sheathed with plywood or OSB, trucked to the construction site, and assembled into a complete building frame. TRUE 112. Structural insulated panels (SIPS) are a popular choice for the construction of highly energy-efficient homes and small buildings. TRUE 113. A manufactured home is a highly energy-efficient building constructed of structural insulated panels that are treated to be weather resistant. FALSE Medium-density fiberboard (MDF) : A fine-grained wood fiber and resin panel product. Touch sanded : In plywood, lightly sanded to produce a smoother, flatter surface. Medium-density overlay (MDO) : A medium-weight, resin-treated overlay applied to plywood panels to achieve a smoother, more durable face. High-density overlay (HDO) : A resintreated overlay applied to plywood panels to achieve a smoother, more durable face. High-lift grouting A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in story-high increments. Span rating : The number stamped on a sheet of plywood or other wood building panel to indicate how far in inches it may span between supports. Performance category : A system for specifying the nominal thickness of a structural wood panel. Actual panel thickness may deviate from the performance category within accepted tolerances.

Hardboard : A very dense panel product, usually with at least one smooth face, made of highly compressed wood fibers. Preservative-treated wood : Wood that has been impregnated with preservative chemicals to increase its resistance to decay and biological attack; also commonly called pressure-treated wood. Pressure-treated wood : Wood that has been impregnated with chemicals under pressure for the purpose of retarding decay or reducing combustibility. Chromated copper arsenate (CCA) : A chemical used to protect wood against attack by decay and insects. Due to toxicity concerns, this chemical has been phased out of most treated wood used in residential and commercial building construction. Alkaline copper quat (ACQ) : A chemical used to preserve wood against attack by decay and insects. Copper boron azole (CBA and CA) : A chemical used to preserve wood against attack by decay and insects. Sodium borate (SBX): A chemical used to preserve wood against attack by decay and insects. Incising : Short, repetitive cuts made in the surface of a wood member to increase its absorption of treatment chemicals. Nail : A sharp-pointed metal pin used for fastening wood. Common nail : A standard-sized nail used for the fastening of rough framing members in wood light frame construction. Box nail : A nail with a slenderer shank than a common nail; used for fastening framing members in wood light frame construction. Finish nail : A relatively thin nail with a very small head; used for fastening trim and other finish woodwork items. Brad : A small finish nail. Brake: A machine used to form lengths of sheet metal into bent shapes. Penny (d) : A designation of nail size, abbreviated as “d.” Lag screw : A large-diameter wood screw with a square or hexagonal head. Self-drilling wood screw Bolt : A fastener, usually metallic, consisting of a cylindrical body with a head at one end and a helical thread at the other, intended to be inserted through holes in adjoining pieces of material and closed with a threaded nut. Nut : A fastener, usually metallic, with internal helical threads, used to close a bolt. Washer : A steel disk with a hole in the middle, used to spread the load from a bolt, screw, or nail across a wider area of material. Toothed plate : A multipronged fastener made from stamped sheet metal, used to join members of a lightwood wood truss. Joist hanger : A sheet metal device used to create a structural connection where a joist is framed into a header or a ledger. Formaldehyde : An organic compound known to cause a range of adverse human health effects, traditionally used in the manufacture of wood product adhesives and binders. See also Phenolformaldehyde and Urea- formaldehyde. Phenol-formaldehyde (PF) : A structural wood adhesive and binder, suitable for exterior exposure, and associated with relatively low formaldehyde gas emissions. Urea-formaldehyde (UF) : A structural wood adhesive, not suitable for exterior exposure, and associated with relatively high formaldehyde gas emissions. Truss : A triangulated arrangement of structural members that reduces monaxial external forces to a set of axial forces in its members. See also Vierendeel truss. Structural insulated panel (SIP) : A panel consisting of two face sheets of wood panel bonded together by plastic foam core. Sandwich panel : A panel consisting of two outer faces of wood, metal, gypsum, or concrete bonded to a core of insulating foam. Stressed-skin panel (SSP) : A panel consisting of two face sheets of wood, metal, or concrete bonded to perpendicular spacer ribs or framing members such that the panel can act as a composite structural panel. Panelized construction : A method of prefabricated wood light frame construction, in which whole sections of walls or floors are framed and sheathed in the factory and then transported to the construction site for erection. Manufactured home : A transportable house that is entirely factory built on a steel underframe supported by wheels; euphemistically referred to as a mobile home. Modular home : A house assembled on the site from boxlike factory-built sections. Guided Reading Questions Trees Tree Growth  Bark: Outermost protective layer (A: dead, B: living)  Cambium layer (C): Source of new wood cells  Sapwood (D): Living cells that store and transport nutrients  Heartwood (E): Dead cells that contribute to structural strength  Pith (F): Innermost, first year’s growth

 Annual growth rings: Result from differences in rate of tree growth and density of cells, from spring to summer Softwoods  From cone-bearing (coniferous) trees  Relatively simple cell structure  Generally, plain figure (pattern of grain and surface features)  Mostly originating from North American forests  Fast-growing, plentiful, relatively inexpensive  Generally soft, easily worked  Uses: o structural wood products o finish trim, shingles and siding o flooring  But not all softwoods are soft. For example, Douglas Fir is harder than some hardwoods. Hardwoods  From broadleafed (deciduous) trees  More complex cell structure  Often more interesting figure  Harvested from around the world  Slower growing, generally more expensive than softwoods

 Denser, with greater variety of colors and figure o fine trim, paneling o flooring o fine cabinet work, furniture Certified Wood  Sustainable forestry management o Protect forest ecosystem o Maintain long term forest economic viability o Some programs also address social responsibilities, for example, the land rights of indigenous peoples.  Forest Stewardship Council (FSC): Only certifying organization currently recognized for LEED certification Lumber Sawing  Plainsawn : growth rings roughly parallel to wider face of board  Quartersawn : growth rings close to perpendicular to wider face of board Plainsawn lumber  Broader grain pattern on wide face  Greater distortion during drying  More uneven surface erosion or wear  More efficiently sawn from log; less costly  Also called flatsawn, flat grain Quartersawn lumber  More narrowly spaced grain pattern on wide face  Less distortion during drying  More even surface erosion or wear  More costly to saw from log  Riftsawn : angle of grain falls between perfectly quarter sawn and plainsawn  Also called edge sawn, edge grain, vertical grain Seasoning  After lumber is sawn, it is seasoned (dried), either in air or in kilns.  Seasoned lumber is lighter, stronger, and stiffer than green (unseasoned) lumber.  Decay causing fungi cannot survive in wood with a moisture content (MC) below 20%.  As wood dries below approximately 30 percent MC, it shrinks, mostly in cross section, and only slightly in length.  Difference between rates of tangential and radial shrinkage cause distortions in shape, especially in flatsawn lumber.  Wood eventually dries to equilibrium with the surrounding air, reaching its equilibrium moisture content (EMC). o EMC for exterior uses: 15% - 19% o EMC for interior uses: 5% - 11% Surfacing Lumber is surfaced to make it smooth and more dimensionally precise.  Framing lumber: usually surfaced four sides ( S4S )  Finish lumber: may be S4S, or surfaced two sides ( S2S ), the other sides to be sawn and surfaced by the woodworker  Surfacing after seasoning ( S-DRY ): removes some drying distortions  Surfacing before seasoning ( S-GRN ): sometimes more economical; best for wood species that don't distort excessively as they dry  Construction planking: unsurfaced , resulting in a plank that is stronger (no material has been removed) and more slip-resistant

Structural Grading  Framing lumber pieces are graded and stamped for structural strength and stiffness.  Higher structural grades have fewer defects, and when left exposed, are generally also more attractive.  Grading is most commonly performed visually, by trained inspectors, or it may be done by machine. Appearance Grading  Finish lumber is graded for the extent of defects, such as knots, and other appearance characteristics.  Appearance grading is always performed visually. Structural Properties of Wood  Wood has both useful tensile and compressive strength.

 Strength varies significantly with direction of grain, species, and presence of knots or other defects.  Defect-free wood is close to the strength of steel on a per-weight basis, but typical grades are weaker.  Strength also varies with duration of load, moisture content, chemical treatments, temperature, size and shape of piece. Lumber Dimensions  Actual sizes are less than nominal size . E.g.: o 1x4 actual size is approximately ¾" x 3½" o 2x4 is 1½" x 3½" o 2x10 is 1½" x 9¼"  In U.S., lumber is priced by the board foot , based on nominal, not actual dimensions: o 12 sq. in. nominal cross-section, 1 foot long = 1 board foot o E.g., an 8-foot 2x12 = (2x12)/12 x 8 = 16 board feet Wood Products Manufactured Wood Products Solid wood and wood fiber materials can be used in the manufacture of various wood products.  More sizes and shapes  Fewer defects  More consistent quality  More efficient use of wood materials  In some cases, stronger and stiffer than solid wood members Glue-Laminated Wood Beams made from glued, solid lumber pieces  Readily available in larger sizes, stronger and stiffer, than solid wood  Can be curved  Uses high-grade pieces efficiently, only in the parts of the beam with high stress levels, while using lower grade materials in other areas Structural Composite Lumber In order of increasing strength:  Laminated strand lumber ( LSL ) and oriented strand lumber ( OSL ): glued shredded wood strips  Laminated veneer lumber ( LVL ): glued, full-depth veneers  Parallel strand lumber ( PSL ): glued veneer strips  Used as beams, headers (short beams over openings), studs, nonstructural rim boards, etc. Wood-Plastic Composites (WPCs)  Made from mixtures of wood fibers and plastics  May be prefinished  Used for exterior decking, wood trim, etc.  Less stiff and greater thermal expansion and contraction than solid lumber  Also plastic lumber: greater than 50% plastic; has both finish and structural applications Structural Wood Panels  Plywood : laminated veneers  Composite panels : face veneers bonded to solid core  Oriented strand board ( OSB ), shown at right: glued, shredded strands, like LSL  Particleboard : glued particles, smaller than OSB strands  Fiberboard : glued, very fine-grained wood particles  Standard panel sizes: 4' x 8', 5/16" to 1 1/8" thick  Used as sheathing on framed walls and roofs, and subflooring over floor framing

 Span Rating: Example, 32/16, may be used as roof sheathing over rafters spaced at 32" or as subflooring over joists spaced at 16"  Exposure Durability Classification o Exterior: exterior glue, best veneers; for permanent exterior siding o Exposure 1: exterior glue, medium quality veneers; for interior use, with prolonged exposure during construction; MOST COMMON o Exposure 2: for interior use, minimum wetting during construction  Plywood Veneer Grades A-D: Lower grades are less smooth and have more defects, such as knot holes. Examples:  o CDX: C and D faces, with exterior glue; for exterior sheathing o C-plugged-D flooring underlayment: C-plugged face provides an especially smooth surface beneath carpet or resilient flooring materials o Example structural panel grade stamps:  Panel products are also used in a variety of nonstructural applications such as finish paneling and cabinet work Wood Chemical Treatments  Fire-retardant treated wood: Chemical salts pressure-impregnated into wood to reduce its combustibility o Limited application, used where building code restricts the use of combustible materials  Preservative-treated wood: Protect wood from decay and insect attack o Wood exposed to the weather, in contact with the ground, or in areas of high termite risk Wood Preservative Treatments Pressure-impregnated waterborne salts are most common:  CCA: Contains arsenic; common in the past, but use has become restricted  ACQ, CBA, CA: High concentrations of copper; most common, require corrosion resistant fasteners and hardware  SBX and other borate compounds: noncorrosive, nontoxic; primarily for insect resistance; not for exterior exposure or ground contact Wood Fasteners Nails  Inexpensive, fast and easy to install  Sized in pennies (d), e.g.: o 16d: 3½"; 8d: 2½"; 2d: 1"  Materials: o bright (plain steel) o galvanized (zinc-coated for corrosion resistance) o stainless steel o aluminum, copper, etc.  Many shapes for different uses  May be driven by hand or nail gun

Screws & Bolts  Greater holding power than nails  More expensive and time-consuming to install  Bolts require pre-drilled holes.  Some screws require pilot holes, some are self-drilling.  Great variety of shapes, sizes, head styles, driver shapes

Manufactured Wood Products Trusses  Light wood members (2x4, 2x6) joined with toothed plates  Long-span capability  Rapidly erected on site using light-duty cranes  Congested attic space I-Joists  Can span further than solid lumber, using less raw material  Top and bottom flanges of solid lumber, or composite material (LVL shown here)  Webs of OSB or plywood Panel Components  Can act structurally, or be attached to a structural frame Factory-Built Housing  Manufactured homes (mobile homes): Built on towable chassis, to U.S. HUD standards  Modular Construction : Constructed to local building code requirements, but factory-built and trucked to construction site Additional Resources  Plain Sawn vs Quarter Sawn  Types of Wood Chapter 4 - Heavy Timber Frame Construction Thought Points  Focus on details of Mill construction and its fire resistance. Key Terms Wattle and daub: Mud plaster (daub) applied to a primitive lath of woven twigs or reeds (wattle). Cruck: A framing member cut from a bent tree so as to form one-half of a rigid frame. Heavy Timber Construction: A type of wood construction made from large wood members and solid timber decking in a post-and-beam configuration; in the International Building Code, buildings of Type IV HT construction, consisting of heavy timber interior construction and noncombustible exterior walls, which are considered to have moderate fire-resistive properties. Mill construction: The traditional name for a construction type consisting of exterior masonry bearing walls and an interior framework of heavy timbers and solid timber decking; also called slow-burn construction. Chamfer: A flattening of a longitudinal edge of a solid member on a plane that lies at an angle of 45 degrees to the adjoining planes. Firecut: A sloping end cut on a wood beam or joist where it enters a masonry wall. Tongue and groove: An interlocking edge detail for joining planks or panels. Glue-laminated wood: A wood member made up of a large number of small strips of wood glued together. Bent: A plane of framing consisting of beams and columns joined together, often with rigid joints. Purlin: A beam that spans across the slope of a steep roof to support the roof decking. Shear connection: A connection designed to resist only the tendency of one member to slide past the other, and not, as in a moment connection, to resist any tendency of the members to rotate with respect to one another; in steel frame construction, a simple connection. Rigid frame: Two columns and a beam or beams attached to one another with moment connections; a moment-resisting frame. Tie rod: A steel rod that acts in tension. Arch: A structural device that supports a vertical load by translating it into axial inclined forces at its supports. Performance-based building code: A set of legal regulations that mandate performance outcomes rather than specific construction details and practices. Prescriptive building code: A set of legal regulations that mandate specific construction details and practices rather than establish performance standards. Guided Reading Questions Answer

1. Today, heavy timber frame construction may include glulams, structural composite lumber, and other manufactured wood products in addition to solid sawn wood members and a greater diversity of connector types. TRUE 2. In the heavy timber construction type, wooden structural members must meet length requirements and exterior walls must be coated in plastic or other environmental protective sealants. FALSE 3. The International Building Code limits the heavy timber construction type to six stories or less. TRUE 4. Heavy timber framing may not be used in other building code construction types where smaller wood members are permitted. FALSE 5. Traditional heavy timber frame structures rely on the natural resistance of large wood members for protection from fire, because compared to smaller pieces of wood, larger members are slow to catch fire and burn. TRUE 6. When larger members do burn, the burnt layer, or char, that forms on their exposed faces provide more access for another fire to take hold and burn the inner portions. FALSE 7. A heavy timber beam, though deeply charred by gradual burning, will maintain sufficient capacity to carry loads long after an unprotected steel beam exposed to the same conditions has lost strength and failed. TRUE 8. Encapsulation of mass timber most frequently takes the form of one or more layers of gypsum board applied directly to the faces of the members. TRUE 9. Beam ends at exterior masonry walls of mill construction are firecut so they will readily fall from the masonry wall pocket in a floor framing collapse caused by fire without destabilizing the wall itself. TRUE 10. Wood is roughly three times weaker in compression parallel to grain than perpendicular to grain. FALSE 11. Where beams and columns are stacked, the beam shrinkage at each floor level accumulates, and at upper floor and roof levels the dimensional movements become unacceptably large. TRUE 12. Heavy timber connections that depend on mechanical fasteners for the transfer of loads between members are more efficient and economical than those that rely on direct bearing. FALSE 13. Building codes require that type IV Heavy Timber buildings have floors and roofs of solid wood construction without concealed combustible cavities. TRUE 14. A heavy timber frame building with exterior masonry or concrete bearing walls may not be braced on the lateral resistance of the exterior walls against wind and seismic forces. FALSE 15. Heavy timber buildings are especially convenient for the designer because they readily provide the cavities that are used to conceal building services. FALSE 16. Where concealed combustible spaces are created in Type IV Heavy Timber buildings, fireblocking materials must be installed within the concealed spaces. TRUE

17. Cross-laminated timbers are fabricated to the required size and shape as well as cutouts for conduit, piping, and other building services and other modifications are completed before panels are shipped to the construction site. TRUE 18. Exterior cladding, thermal insulation, and air and water-resistive barrier membranes are applied to the outside of exterior cross-laminated timber panels to keep the panels within the heated and dry interior environment. TRUE 19. The interior panels of a completed cross-laminated timber structure may be left exposed or covered with gypsum. TRUE 20. Even where mass timber or heavy timber frame members must meet fire resistance rating requirements, the connections supporting these elements are not required to meet the same ratings. FALSE 21. When relying on cross-laminated timber for lateral force resistance (and especially, for resistance to seismic forces), either panel strength must be overdesigned to compensate for brittle behavior or ductility must be introduced through the connections between panels. TRUE 22. At this time, CLT shear walls are considered feasible for lateral force resisting systems in mass timber structures as high as approximately 3 to 5 stories. FALSE 23. Two options for protecting wood from deteriorating or changing volume by absorbing unwanted water during construction include scheduling construction to occur during dry seasons of the year, and temporarily tenting the building structure. TRUE 24. Heavy timber beams and cross-laminated timber panels are rarely used in combination with cast-in-place concrete due to the different rates expansion of the materials causing uneven stress. FALSE 25. Concrete is cast on top of wood panels or over wood beams, fully covering the connectors, so that these components share stresses and deflect together as one element. TRUE 26. Very large wood beams are usually built up of wood laminations or strands because they’re stronger and more dimensionally stable than sawn wood beams. TRUE Guided Reading Questions Heavy Timber Frame Construction History  Simple timber-framed structures appear with the oldest know civilizations .  The traditional braced frame structure first appears in the middle ages. Timber Construction History  Till the Late 1800s most o Construction was Timber (and/or masonry) with o Wood to Wood Connections

WHY?  Timber (Trees) Plentiful  Craftsman Available  Nails & Fasteners Rare & Expensive  Few Alternatives Contemporary  Contemporary timber frame construction may be used for both residential and nonresidential structures. Timber Construction Today Why so Little Timber Construction Today?  Alternate Structural Systems Available  For Both Residential & Commercial Commercial Alternatives Concrete & Steel (late 1800s) Advantages over Timber  Greater spans  Lighter structures  Increased fire resistance  Increased versatility  More economical Residential Alternatives Light Wood Framing (mid 1800s) Fasteners available at reasonable price Advantages  Lighter structure  Used less material  Quicker to erect  More economical Timber Construction Where/when is timber construction typically used today?  Aesthetics, appearance, feel important o Uniqueness of Timber Construction o Common Uses  High end residential  Restaurants, lodges, etc.  Public areas requiring aesthetics Fire-Resistive Heavy Timber Construction Resistance to Fire of Large Timbers  Large wood members have greater resistance to fire than unprotected steel.  Steel, due to its high thermal conductivity, quickly heats up and loses strength during fires.  Large timbers are slow to absorb heat, slow to catch fire, and slow to burn.  The charred outer layer of a partially-burned timber insulates and protects the inner undamaged portion of the timber which retains the capacity to carry some load. Heavy Timber Construction  Fire-resistive, traditional Mill Construction consists of heavy timber framing within brick masonry exterior walls.  In the contemporary building code, Type IV Heavy Timber construction requires heavy timber framing within noncombustible—masonry, steel, or concrete—exterior walls.

 Timbers must meet minimum size requirements to qualify as Type IV-HT construction in the building code.  Members with lesser dimensions are classified as wood light frame (Type V) construction. Wood Shrinkage  Wood column/beam connections are designed to minimize the effects of cross-grain shrinkage that can lead to differential settling between interior framing and exterior walls made of materials that are not prone to shrinkage.

 Traditional cast iron pintle column base.  Contemporary beam/column connection with bearing blocks, split rings , steel straps.

Beam Anchorage Fire cut beam ends: Collapse of beam must not topple supporting wall.

A ventilating air space around the beam end prevents moisture in the masonry wall from seeping into the beam.

Upper clip restrains beam from side-to-side movement while allowing rotation due to structural deflection or beam collapse in a fire. Floor and Roof Decks  Decking comes in depths of 2" to 8", capable of spanning roughly from 5' to more than 20'.  To achieve the required fire-resistance, floor decking must be covered with tongue-and-groove boards or plywood.  Fire-resistive heavy timber floors and roofs must be constructed without concealed cavities where fire could develop undetected.

Bracing Heavy Timber Structures  HT structures may be braced against lateral forces with diagonal framing members, shear walls of masonry or concrete, or rigid panels attached to the building frame.  To meet contemporary standards, historical structures may require insertion of new steel or reinforced concrete bracing elements.  Floor and roof diaphragms must also be securely tied to the supporting structure. Additional Considerations  Lack of concealed cavities for: o MPE rough-in o Building Insulation  Span length limitations typically limited to 20’ Alternatives  Large Beams – often laminated  Heavy timber trusses Connections Connection & Support Details  Detailed to minimize the effect of differential shrinkage  Perimeter Support o Protect from decay o Securely anchored  Proprietary fastening system with self-drilling steel dowels and concealed steel plates  Fabricated steel seat, concealed plates, and exposed through-bolts  Steel plate gusset with tie rod and through-bolts  Copper sheet metal flashing to protect against moisture absorption at vulnerable ends of large timbers exposed to the weather. Longer Spans in Heavy Timber Large Beams  Glulam beams can span over 80', and arches even further. Trusses  Heavy timber trusses can span beyond 200'. Domes  The Washington State Tacoma Dome spans 530'. Uniqueness of Heavy Timber Framing  Positive reaction o Color, grain, & warmer feel of wood  Exposed ceiling beams are become a desired amenity  Economic reality o Forest have diminished in quality o Higher shipping costs Additional Resources  Raising a timber frame  Post and beam or heavy timber frame systems

 Timber Frame Trusses - The 5 Basic Truss Types Chapter 5 - Wood Light Frame Construction Thought Points  Focus on details of light frame construction and construction process.. Key Terms Balloon frame: A wooden building frame composed of closely spaced members nominally 2 inches (50 mm) thick, in which the wall members are single pieces that run from the top of the foundation to the underside of the roof framing. Stud: One of an array of small, closely spaced, parallel wall framing members; a heavy steel pin. Rafter: A framing member that runs up and down the slope of a steep roof. Fireblocking: Wood or other material used to partition concealed spaces within combustible framing; intended to restrict the spread of fire within such spaces. Platform frame: A wooden building frame composed of closely spaced members nominally 2 inches (51 mm) thick in which the wall members do not run past the floor framing members. Sheathing: The rough covering applied to the outside of the roof, wall, or floor framing of a structure. Band joist: A wooden joist running perpendicular to the primary direction of the joists in a floor and closing off the floor platform at the outside face of the building. Also called a rim joist. Subfloor: The loadbearing beneath a finish floor. Sole plate: The horizontal piece of dimension lumber at the bottom of the studs in a wall in a light frame building; also called a bottom plate. Top plate: The horizontal member at the top of the studs in a wall in a light frame building. Ridge board: A nonstructural framing member against which the upper ends of rafters are fastened. Sill: The horizontal bottom portion of a window or door; the exterior surface, usually sloped to shed water, below the bottom of a window or door. Trimmer stud: A shortened stud that carries a header above a wall opening; also called a trimmer stud. Jack stud: A shortened stud that carries a header above a wall opening; also called a trimmer stud. Batter board: Boards mounted on stakes outside the excavation area of a building, used to preserve locations for string lines marking the corners of the building foundation. Framing plan: A diagram showing the arrangement and sizes of the structural members in a floor or roof. Rough carpentry: Framing carpentry, as distinguished from finish carpentry. Sill seal: A compressible material placed between a foundation and a wood sill plate to reduce air infiltration between the outdoors and indoors. Termite shield: A metal flashing placed on top of a concrete foundation to prevent termites from traveling undetected from the ground into the superstructure. Bridging: Bracing or blocking installed between steel or wood joists at intermediate points to stabilize the joists against buckling and, in some cases, to permit adjacent joists to share loads. King stud: A full-length stud nailed alongside a jack stud. Cripple stud: A wood wall framing member that is shorter than full-length studs because it is interrupted by a header or sill. Lateral force: A force acting generally in a horizontal direction, such as wind, earthquake, or soil pressure against a foundation wall. Wracking: Forcing out of plumb. Shear wall: A stiff wall that imparts lateral force resistance to a building frame. Braced frame: A structural building frame strengthened against lateral forces with diagonal members. Collector: A framing component that transfers lateral forces into parts of the structure designed to resist those forces. Drag strut: A framing member or component acting as a collector to transfer lateral forces within the building frame; also called a drag tie. Squash block: Short lengths of framing lumber, inserted under points of concentrated load to prevent overloading of I-joist framing members. Joist: One of a parallel array of light, closely spaced beams used to support a floor deck (floor joist) or low-slope roof (ceiling joist). Ridge beam: A structural beam supporting the upper ends of rafters in a sloped roof, required where the rafters are not tied at their lower ends. Pitch: The slope of a roof or other plane, often expressed as inches of rise per foot of run; a dark, viscous hydrocarbon distilled from coal tar; a viscous resin found in wood. Rise: A difference in elevation, such as the rise of a stair from one floor to the next or the rise per foot of run in a sloping roof. Run: Horizontal dimension in a stair or sloping roof. Framing square: An L-shaped measuring tool used by carpenters to lay out right angle cuts as well as more complicated cuts, such as those required for stairs and sloping roof rafters. Valley: A trough formed by the intersection of two roof slopes. Hip rafter: A roof rafter at the intersection of two sloping roof planes. See also Common rafter. Valley rafter: A diagonal rafter that supports a valley. Pattern rafter: A wood rafter cut to size and shape and then used to trace cuts onto additional wood members so as to assure consistent dimensions among all rafters. Dormer: A structure protruding through the plane of a sloping roof, usually containing a window and having its own smaller roof. Common rafter: A roof rafter that runs parallel to the main slope of the roof. See also Hip rafter.