Week 2 tute exercise (Solution) 2024 (2)

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1 BLDG 2013 Construction Estimating Week 2 Tutorial Exercise: Cost data and pre-tender estimate Name: _________________________ SID: ___________________________ 1. As a consultant QS, discuss three factors affecting your selection of construction cost data in preparing a pre-tender cost estimate for your client. Answers: Students should be able to discuss (not just listing) three factors to be considered in selecting or using an existing cost data (refer to slide - precautions for using existing cost data). For example, to choose a cost database that is easy to understand would help to speed up the estimating process. A reliable cost data would enhance accuracy…students need to discuss three factors. 2. Using the following extract of building price index from the Rawlinson Australian Construction Handbook, calculate the percentage variation in cost between (a) June 2019 and June 2023 for a project in Sydney. (b) June 2020 and June 2023 for a project in Melbourne. Comment on the percentage variation. Answers: (a) Percentage variation = (149.16 – 122.39)/122.39 x 100 = +21.87% Comment: the building price increased by 21.87% over this time period in Sydney. (b) Percentage variation = (144.35 – 125.03)/125.03 x 100 = +15.45% Comment: the building price increased by 14.45% over this time period in Melbourne.

2 3. Further to Question 2(a), calculate the percentage variation in cost for a project that is based in Mudgee, NSW based on the additional information given below: Regional index for Sydney: 100 (base) Regional index for Mudgee: 112 Comment on the percentage variation. Answers: • Percentage variation = (149.16 – 122.39)/122.39 x 100 x 112/100 = +24.50% • Comment: the building price increased by 24.50% over this time period in Mudgee. 4. Why do we need different methods of pre-tender (approximate) estimating? Answers: Students should be able to discuss factors affecting the choice of pre-tender (approximate) estimating method, for e.g., availability of project information, the level of accuracy, the time available to perform the estimating tasks (refer to slide - Selecting a method of pre-tender estimating). For example, factor on ‘availability of project information’, when no drawing is available at the early stage of project, there is a need to rely on unit method. On the other hand, if there are drawings, approximate quantity is needed to achieve high accuracy in estimating tasks. NB: Any discussion or explanation that demonstrates understanding is acceptable. 5. What is the estimated tender price of a single storey 1500m 2 administrative office at today’s prices based on the information given below? Tender price for administrative office in 2015 = $2000/m 2 Tender price index in 2015: 110 Today’s tender price index: 145 Answers: Estimated tender price of a 1500m 2 administrative office at today’s prices = 1500 x $2000 x 145/110

3 6. What is the estimated cost of a 150-seat lecture theatre at today’s prices based on the information given below? Cost per lecture theatre seat in 2018 = $1200 Building cost index in 2018: 120 Today’s building cost index: 145 Answers: Total estimated cost at today’s prices = 150 x $1200 x 145/120 + external works + pilling cost + others 7. What is the estimated cost of a lecture theatre of 180m 2 GFA for a project scheduled for the second quarter of 2024 based on the information given below? Cost per m 2 GFA for lecture theatre in 2018 = $3750 Building cost index in 2018: 120 Today’s building cost index: 145 Index in June 2024: 152 (forecast) Answers: Total estimated cost in the 2nd qtr of 2024 = 180 x $3750 x 152/120 + external works + pilling cost + others 8. As a consultant QS, your client would like to know the probable construction cost for a six-storey mixed residential development project with (i) a basement car park, (ii) two shop units at the ground floor; and (iii) a combination of two- and three- bedroom units at the upper floors (a total of 25 units). The proposed project has a gross floor area of 6,000m 2 . This is his first project and it is important to provide your client with a reliable estimate that is easy to understand. (a) Which method you will be using to estimate the probable cost of the project. (b) Explain how to apply the selected method in (a). Answers: (a) Method: Superficial method (b) How to apply superficial method • Obtain unit rate/m 2 of completed building of the same type, R • Make adjustments for difference in specifications, plan shape, methods of construction, quality of materials, etc., R1 • Multiply the gross floor area, A by the unit rate/m 2 , • Make adjustment for time effect using indices if required. • Allow for external works, piling cost, etc.

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4 9. In preparing a pre-tender estimate for a single storey nursing home project in Sydney with a gross floor area of 3,000m 2 that incorporates high care units, you have access to the current cost data of a similar project as below: (a) Which method you will be using to estimate the probable cost of the project? Justify your selection. (b) Estimate the probable cost of the nursing home project. Answers: (a) Method: Superficial method; Justification: (i) more accurate than unit method, (ii) the cost estimate is related to floor area; (iii) easy and quick method; and (iv) easier to understand compared to unit method. (b) Total estimated cost = (3000 x ($ 3155+$179)) + external works + pilling cost + others 10. Using the following information, evaluate the accuracy of pre-tender estimates of two Consultant QS firms. Which firm is more accurate in estimating project cost at pre-tender stage? QS firm A Project Pre-tender cost estimate($) Accepted tender ($) 1 140,000 150,000 2 900,000 895,000 3 450,000 475,000 4 800,000 785,000 5 480,000 478,000 QS firm B Project Pre-tender cost estimate($) Accepted tender ($) 1 550,000 585,000 2 360,000 355,000 3 90,000 95,000 4 880,000 910,000 5 375,000 380,000 Hint: Calculate mean percentage error for each firm, i.e., overall average of [(pre- tender estimate – accepted tender)/accepted tender x 100)]

5 Answers: QS firm A Project Pre-tender cost estimate($) Accepted tender ($) Pre-tender estimating accuracy (%) 1 140,000 150,000 -6.67 2 900,000 895,000 0.56 3 450,000 475,000 -5.26 4 800,000 785,000 1.91 5 480,000 478,000 0.42 Mean -1.81 QS firm B Project Pre-tender cost estimate($) Accepted tender ($) Pre-tender estimating accuracy (%) 1 550,000 585,000 -5.98 2 360,000 355,000 1.41 3 90,000 95,000 -5.26 4 880,000 910,000 -3.30 5 375,000 380,000 -1.32 Mean -2.89 QS Firm A is more accurate in pre-tender estimating with lower mean % error (closer to zero)

Week 2 tute exercise (Solution) 2024 (2)

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