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# Estimating and costing I Chapter 2.pptx

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# Estimating and costing I Chapter 2.pptx

ESTIMAtion and costing

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### Estimating and costing I Chapter 2.pptx

1. 1. Chapter 2 Types of Estimate 1) Preliminary Estimate/Approximate Estimate It is also called approximate or rough estimate This type of estimate is carried out to find out the estimated cost in very short time. Detailed drawing may not be mandatory. This provides decision for the financial investment and its justification by comparing investment of the different project This is prepared from practical knowledge and comparison of similar works constructed recently
2. 2. Preliminary estimate is prepared in various ways for different Wocks and structure For Building  Per unit basis example for bed for hospital, for seat for cinema halls, for class room for school  plinth area basis  cube content basis  approximate quantity basis For irrigation works  per kilometre basis  command area basis Road and Highways  for kilometre basis depending upon nature class of road width of road thickness of metalling Bridge and Culvert  for running metre depending upon roadway with nature and depth of foundation type of structure Water Supply and Sanitary Works  on the basis of for head population served  on the basis of area covered Overhead Water Tanks  on the basis of capacity for liter or gallion basis
3. 3. Purpose of Preliminary Estimate To investigate feasibility To save time and money To investigate benefit To obtain administrative approval For insurance and tax schedule
4. 4. Types of Preliminary Estimate a) Plinth Area Estimate b) Cube Rate Estimate a)Plinth Area Estimate: Plinth area estimate is prepared by multiplying plinth area by plinth area rate. Civil cost(Building cost)= Plinth area ⅹ Plinth area rate Plinth area = Carpet area(50-65)%+Circulation area(20- 30)%+ Wall area(5-10)%
5. 5. b) Cube Rate Estimate This is the approximate estimate for the building and is based on the cubical content of the building and the cube rate The cube rate is obtained from the cost of the building having similar specification and the construction in the same locality. Cubical content is found out by multiplying by L, B and H of the building. Height is taken from the floor level to the top for flat roof and upto mid height for sloped roof This method is more accurate than plinth area estimate.
6. 6. 2) Detailed Estimate  After getting Administrative approval on rough cost estimate, detailed estimates are prepared. This is the accurate estimate and consists of working out the quantities from detailed drawing(plan, section, elevation) and specification. The detailed estimate shall also provide for the cost of approach road, water supply, electric installations and acquisition of land etc.,
7. 7. Detailed estimate is prepared in two stages 1. Detailed of measurement and calculation of quantities The whole work is divided into different items of work as earthwork , concrete work , brickwork, RCC , finishing work etc. and the items are classified under different sub head. Details of measurement of each item of work are taken out and quantities under each items are computed in details of measurement form Details of measurement form Items no. Description of work No. L B H Q Remarks 1 Earthwork in excavation 1 2 2 1 4m3 2 Soling 1 2 2 4m2
8. 8. 2. Abstract of estimated cost The quantities of each items of work and the workable rate is used to find the total cost of the work. These quantities, rate and the total cost is workout in a prescribed form called abstract of estimate form. Abstract form Items no. Description of work Quantity Unit Rate(Rs) Amount(Rs) 1 Earthwork in excavation 4 m3 1000 4000 2 Soling 4 m2 50 200
9. 9. Data Required for Preparation of Detail Estimate i) Drawing:  Drawings are the basis from which quantities of various items of work are calculated. Drawing should show plan ,elevation and sectional details wherever necessary.  The drawing should be fully dimensioned. ii) Schedule of rates: The rate of various items of work, material, labour are needed to find the estimated cost.  The quantities of different items of work are calculated from drawing and then multiplied by rates
10. 10. iii) Specification:  It is a part of contract document containing information regarding the quality of material and workmanship. Types of Specification a) General or brief specification  It contains short description about the work to be performed and the material to be used.  Used by designed team for estimation  The nature and class of works are described b) Detailed specification  This describes every items of works separately.  These are written as per BoQ ,which specify material to be used, its quality, workmanship  These are written as far as possible in the same sequence of order as the work is carried out.
11. 11. iv)Methods of measurement Modes of measurement are necessary to determine the correct quantity.
12. 12. 3) Revised estimate It is a detail estimate which are prepared when the sanction estimate is likely to exceed by more than 5%. This may be due to rate being insufficient or from any cause except for the alteration of structural component.(Due to change in rate and change in quantity of material) The revised estimate should show the comparative statement of different items of works; its quality; and rate(cost) under original and revised estimate side by side Additional or revision of drawing is not necessary
13. 13. Comparative Statement Form Items Description of work Existing Estimate Revised Estimate Reason Q Rate Amount Q Rate Amount 1 E/W 10cum 450 4500 15 cum 450 6750 Q changed but rate being same 2 PCC(1:2:4) 1 cum 12000 12000 1 cum 1500 0 15000 Q same but rate being changed
14. 14. 4) Supplementary estimate This is the detailed estimate and is prepared when the additional work are required to be supplement the original work or when further development is required during the progress of the work. Supplementary estimate is prepared due to material deviation of structural nature from the design originally approved. This is estimate for the additional work only. Additional or revision of drawing may be necessary Comparative abstract form is not required.
15. 15. 5) Annual Repair and Maintenance Estimate It is a detailed estimate and is prepared to maintain the structure or work in same , economical and serviceable condition after completion of project. An estimate is prepared for the items which requires renewal, replacement, repair etc. The cost of annual repair and maintenance estimate should not exceed more than 1.5% of the capital cost For building it includes colour washing, maintenance of plumbing works, seepage etc.
16. 16. 6)Extension and Improvement Estimate If further changes and extension are required to be made in old work , the cost of which can’t be met out of annual repair and maintenance estimate , a detailed estimate of additional work is prepared, called extension and improvement estimate. It requires a)Existing Drawing b)Drawing of additional or changed works c)Rate
17. 17. 7) Complete estimate This is an estimated cost of all items which are related to the work in addition to the main contract or to the detailed estimate. This includes the following cost a) Cost of land b) Cost of legal expenses between owner and contractor c) Engineering fees(Cost for preparation of plans, design, estimate, and sanction fees d) W/S sanitary and electrification charge e) Contingencies f) Miscellaneous viz; transportation cost etc.
18. 18. Thumb Rule for Carpet Area For office building Carpet area =60 to 75% of plinth area For Residential Building Carpet area =50 to 65% of plinth area Wall area = 5 to 10% of plinth area Water supply = 4 to 5% Sanitary charge = 4 to 5 % of building cost Electrification charge = 9 to 12% of building cost
19. 19. Numerical 1)Prepare preliminary estimate of a building having plinth area 5600sqm and plinth area rate Rs 30000 . i)Water supply and sanitary charge 8% of building cost. ii)Electrification charge 9%of the buiding cost. iii) Contingencies charge 3% of overall cost. iv) Supervision charge 5% of overall cost.
20. 20. solutions 1) Building cost = Plinth area ⅹ Plinth area rate = 5600 ⅹ 30000 = Rs 168000000 2)Water supply and sanitary charge =8% of B.C = 8 100 ⅹ 168000000 = Rs 13440000 3)Electrification charge = 9% of B.C = 9 100 ⅹ 168000000 = Rs 15120000
21. 21. A) Overall cost =1 + 2 +3 = Rs168000000+Rs13440000+Rs15120000 =Rs196560000 4) Contingencies charge=3% of overall cost = 3 100 ⅹ Rs196560000 = Rs 5896800 5) Supervision charge = 5% of overall cost = 5 100 ⅹ Rs196560000 =Rs 9828000
22. 22. Total preliminary estimate = overall cost +contingencies charge + supervision =Rs 9828000+Rs 196560000+Rs 5896800 =Rs 212284800
23. 23. 2)Prepare a preliminary estimate of a building having carpet area 1800sqm circulation area and wall area being 30% and 10% of plinth area respectively. Given i) Plinth area rate = Rs 30000 per sqm ii) W/S and sanitation charge = 8% of building cost iii) Electrical installation charge = 9% of Building cost iv) Contingencies and supervision = 8% of overall cost.
24. 24. Solution Let, plinth area of building = 𝑥 m2 Plinth area = Carpet area + Circulation area + wall area 𝑥 = 1800 + 30 100 𝑥 + 10 100 𝑥 𝑥 = 1800 + 0.3 𝑥 + 0.1 𝑥 𝑥 - 0 .4 𝑥 = 1800 𝑥 = 3000m2 i) B.C = Plinth area x Plinth area rate B.C = 3000 x 30000 = Rs 90000000
25. 25. ii) Water supply and sanitary charge = 8% of B.C = 8/100 x 90000000 = Rs7200000 iii) Electrification charge = 9% of B.C = 9/100 x 90000000 = Rs 81,000,00 Overall cost= i + ii +iii =Rs 10,53,000,00 Contingencies and supervision charge =8% of overall cost = 8/100 x 1053000 = Rs 8424000 Total cost of Building = O.C + Contingencies and Supervision charge = 105300000 + 8424000 = Rs 113724000
26. 26. Conversion of system of units 11 Length 1cm = 10mm 1m = 100 cm 1km = 1000m 1 inch = 2.54cm 1ft = 12 inch 1m = 3.28 ft 1 mile = 1.609 km Area 1ropani = 16 aana=508.74sqm=5476s qft 1aana = 4 paisa 1paisa = 4 daam 1 hectare= 104 m2 1 bigha = 20 kattha 1 Katha = 20 dhur 1bigha = 13.31 ropani Weight 1 MT= 1000kg=1 tonne 1kg = 1000gm
27. 27. Numerical on Cube Rate method. Q. A person Construct a building of plinth area equal to 100 square metre on a plot of land in a certain locality at a cost of 20 lakhs .The height of the building from ground level to the top of the roof is 3.5 metre and a parapet Wall of height equal to 80 cm is constructed on a terrace .Determine the cost of similar building of plinth area equal to 135 square metre to be constructed in the same locality by plinth area rate and volume(cube) rate method. Building cost=Cubical volume*cube rate