Mumbai University > CIVIL > Sem 7 > Quantity survey, Estimation and valuation

Marks: 10 M

Year: May 2013, Dec 2012

The following are the common methods used to estimate buildings:

1. Plinth area or square meter method.
2. Cubic rate or cubic meter method.
3. Approximate quantities with bill method
4. Service unit or unit rate method.
5. Bay method
6. Cost comparison method
7. Cost from materials and labour.

Approximate Quantities with Bill Method:-

1. Multiply the total length of the walls of a building in a running meter by the cost of construction per meter length of such a wall. The total length of the walls of a building is worked out from the plan.
2. Different sections of walls in a building are considered separately. A section of wall includes all items of works from foundation concrete to roofing. Thus, the cost of excavation, foundation concrete on roof, parapet, plastering and finishing on walls, etc. per meter length are accounted. The cost of a wall below and above plinth level should be kept separate.
3. In order to spread the proportionate cost for items of works as stated above on running meter length of the wall, their approximate quantities and cost are calculated.
4. Thus, it is better to find out the estimated cost separately: a. cost of wall including foundation and surface finishing, b. cost for flooring c. cost of woodwork and d. cost of roofing.

Cost comparison method:-

1. By this method approximate estimates are prepared for prototype structures or units consisting several works after comparing with the parts records of expenses for such works.
2. For example when prototype staff quarters or Railway station etc. are required to be estimated approximately then the estimate for such prototype works are prepared by comparing the previous cost with the present market rates, normally by increasing the past cost on a percentage basis.
3. Such an estimate can be prepared quickly even during meetings. But expert knowledge is necessary to estimate the present cost of construction as compared to the previous recorded cost.

Cost from materials and labors:-

1. In this method approximate quantities of materials and labour required per sq m of the plinth are for a proposed building are worked out arbitrarily or with the help of the Empirical equations developed by Central Building Research Institute (C.B.R.I) Roorkee and multiplied by the total plinth are of the building.

2. Equations for Materials & Labour requirement for structure in four-storeyed (RCC Frames Building),

   A=Plinth area in sq.