The approximate estimate is done in order to find out an approximate cost in very short time before starting the project. The estimation is made before selecting the final specification and design of the project. This method is also known as preliminary or rough estimate.
Purpose Of Approximate Estimate:
1. To evaluate the cost of a project in short time.
2. To evaluate the difference between several options.
3. To check the final cost of the project that is calculated by detailed estimation.
Methods Of Approximate Estimate:
A. Square Metre Or plinth Area Method:
This estimation is done by selecting the price of 1 square meter area of a building. It is mainly adopted for calculating the cost of following buildings:
- Office Buildings.
- Residential Buildings.
- School Buildings.
- Apartment/Flat Buildings.
This method is considered as the best method for calculating the cost of new buildings.
In case of multi-storeyed buildings, the following assumptions are to be considered for the estimation.
1. For 1 square meter area, the cost of all the floors with basement and roof are in equal costs.
2. The cost of the basement is 60% of the floor.
3. The cost of the roof is 40% of the floors.
B. Cubic Rate Or Cubic Meter Method:
This method gives more exact result comparatively than the square meter method.
For multi-storeyed buildings, the following assumptions are considered.
1. For 1 meter cube area the costs of all floors are equal in costs.
2. The cost of the basement is 60% of the cost of different floors.
The volume of the floor is determined as
Volume = Area × Height of one floor
The height of one floor is found out by the following guidelines:
1. Ground Floor: The height of ground floor is calculated from the top of the footing to the middle of the parapet.
2. First Floor: The height of the first floor is calculated from the ground rooftop to the middle of the parapet.
3. Other Floors: The height of other floors are calculated from floor to floor.
Besides these methods, there are some other approximate methods such as
1. Cost comparison method.
2. Unit rate method.
3. Approximate quantities with bill method.
4. Bay method.
5. The cost of materials and labor method.