Methods of Approximate Estimate | Civil Engineering Optional Notes for UPSC PDF Download

Methods of Approximate Estimate Preparation

The following are the methods used for the preparation of approximate construction cost estimates:

1. Plinth Area Method
2. Cubical Contents Method
3. Unit Base Method
4. Approximate Quantity Method

1. Plinth Area Method

The construction cost is determined by multiplying the plinth area by the plinth area rate. The area is obtained by multiplying the length and breadth (outer dimensions of the building).

• Quality and quantity of materials
• Labor costs
• Type of foundation
• Building height
• Roofing
• Woodwork
• Fixtures
• Number of stories

• Area of walls at floor level
• Internal shafts for sanitary installations (not exceeding 2.0 sqm), lifts, air-conditioning ducts
• Area of barsati at terrace level (a covered space open on one side, used as a shelter during the rainy season)
• Non-cantilever porches

• Area of lofts
• Unenclosed balconies
• Architectural bands, cornices, etc.
• Domes and towers projecting above terrace level
• Box louvres and vertical sun breakers

2. Cubical Contents Method

This method is generally used for multi-storeyed buildings and is more accurate than the plinth area method and the unit base method. The cost of a structure is calculated approximately by multiplying the total cubical contents (volume of buildings) by the local cubic rate.

• Volume = Length x Breadth x Height (measured outside walls, excluding the plinth offset)
• Cost of building = Volume x Rate per unit volume

Note: The cost of string courses, cornices, corbelling, etc., is typically neglected.

3. Unit Base Method

In this method, the cost of the structure is determined by multiplying the total number of units by the unit rate of each item.

• For schools and colleges, the unit is 'one student.'
• For hospitals, the unit is 'one bed.'

• Unit Rate = Actual expenditure or cost of a similar building nearby / Number of units

4. Approximate Quantity Method

This method divides the structure into two parts: the foundation (including plinth) and the superstructure.

1. Determine the cost per running meter of the foundation (including plinth) and multiply by the total length of the foundation to get the total cost of the foundation.
2. Determine the cost per running meter of the superstructure and multiply by the total length of all the superstructure walls to get the total cost of the superstructure.
3. Add the total cost of the foundation (including plinth) to the total cost of the superstructure to obtain the total cost of the structure.

• A line plan of the proposed structure for accurate computations.

By understanding these methods, construction professionals can prepare reliable and accurate approximate cost estimates, ensuring better planning and resource allocation for construction projects.