There are three different methods of estimation Center line method, Long and short wall method, And Crossing method. We will discuss center line method briefly for the estimation of materials.
What Is Center Line Method?
In this method of estimation, the total center line length of walls in a building is first calculated, then the center line length is multiplied with the breadth and depth of the respective items to get the total quantity at a time.
The center line length for different sections of walls in a building shall be worked out separately. For verandah walls or partition walls joining the main walls, the center line length shall be reduced by half of the breadth of the layer of the main wall that joins with the partition or verandah wall at the same level. The number of such joints is studied first to obtain the center line length.
Let us take an example:
For One Room Building
First, we need to calculate the total center line length of the building.
Total center line length = 2 x 5.3 + 2 x 4.3 = 19.2 m.
1. Earthwork in excavation = Total center line length x breadth x depth
= 19.2 x 0.9 x 0.9
= 15.52 m3
2. Concrete in foundation = 19.2 x 0.9 x 0.3 = 5.18 m3
3. a) Brickwork in foundation for 1st footing = 19.2 x 0.6 x 0.3 m3
4. Brickwork in superstructure = 19.2 x 3.5 x 0.3 = 20.16 m3
For Two Room Building:
Total center line length = 2 x (5.3+5.3) + 3 x 4.3 = 34.1 m.
1. Earthwork in excavation = Total center line length x breadth x depth
= 34.1 x 0.9 x (0.3+0.3+0.3)
= 27.62 m3
2. Concrete in foundation = 34.1 x 0.9 x 0.3 = 9.20 m3
3. a) Brickwork in foundation for 1st footing = 34.1 x 0.6 x 0.3 = 6.13 m3
b) Brickwork in foundation for 2nd footing = 34.1 x 0.5 x 0.3 = 5.11 m3
Thus you can estimate the quantity of different items such as
Quantity of D.P.C = Total Centre line length x Breadth of foundation x Thickness of D.P.C
Quantity of plinth beam = Total Centre line length x Breadth of the beam x Depth of beam.
Quantity of wall plaster for 2 sides = Total center line length x Height of wall x Thickness of plaster.
Source: Dailycivil
