Basics in Building Construction

Building Components And Types

Lesson 30 : Construction Cost Estimation

Unit Cost

Cost of a particular work per unit can be arrived by calculating the cost of different materials and man power required. The information required to arrive at unit cost are

1. Quantities of different materials required per unit
2. Cost of each material per unit at site
3. Requirement of labour per unit.
4. Local labour charges
5. Cost of temporary supporting structures such as centring shultering per unit.

The unit cost can vary according to the quality of material. The cost of material at site includes the cost of material at place of origin plus conveyance charges.

Types Of Cost Estimates

For residential building most common types of cost estimates are

1. Plinth Area Estimate
2. Detailed estimate

1. Plinth Area Estimate This is the most commonly adopted ready rekoner cost estimating procedure of a building. In residential buildings more or less the specifications are common and arrangement of cross walls does not vary much compared to commercial buildings. Thus the volume of walls of a single bedroom house and a three bedroom house co-relate proportionately with the area of the house.



The plinth area should be the area occupied by a building at a particular floor level and should not include area of courtyard or any other open area.

After making a detailed estimate and abstract of estimated cost for a building the rate per square meter is calculated by dividing the estimated cost with the plinth area of the house. This is called as “plinth area rate”. For arriving approximate cost of a similar building this plinth area rate should be multiplied with the plinth area of the side building.

For example, if plinth area rate of a locality is Rs. 5000/- per square meter, the approximate cost of a similar proposed building of 80 square meter plinth area shall be Rs. 5000 x 80 = Rs. 4,00,000. This estimate is however, approximate and the actual cost may vary by up to 10% more or less. Change of locality also causes slight variation due to increase or decrease in material transportation charges and labour.

2. Detailed Estimate This is an estimate which gives accurate cost of the proposed work. For making this estimate a dimensioned drawing along with specifications of the proposal is necessary.



The quantities of different items of work are computed in the prescribed unit of payment i.e. in cubic metres, square meters, etc.

The different works involved in construction of a residential building method of cost estimation are explained below.