Basically there are two main methods of Building Estimate -
Figure shows a room of internal dimensions 4.0 X 3.0 m and the thickness of the wall is 30 cm. The centre line length of the room can be calculated as below -
1. Centre Line method
2. Long wall and short wall method ( Out - to- Out and In - to- In method)
1. Centre Line method- In this method the total centre line length of wall in a building is calculated and the same is multiplied by the breadth and depth of the respective item to get the total quantity of the item.
The method of finding the centre line length of the long and short walls in a building is as follows :
Length of long walls (centre to centre)
= Inner length of room + 1/2 (thickness of wall on one side) + 1/2 ( thickness of wall on other side)
= Inner length of room + one thickness of wall ( if both short walls are of same thickness)
Length of short walls (centre to centre)
= Inner breadth of room + 1/2 (thickness of wall on one side) + 1/2 ( thickness of wall on other side)
= Inner breadth of room + one thickness of wall ( if both long walls are of same thickness)
C/C length of long wall = 4.0+ 1/2 (30cm) +1/2 (30cm)
= 4.0 + 15cm + 15cm
(convert cm into m)
=4.0+0.15+0.15 = 4.30m
C/C length of long wall = 4.30 m
Now
C/C length of short wall = 3.0 + 1/2 (30cm) +1/2 (30cm)
= 3.0 + 15cm + 15cm
(convert cm into m)
= 3.0+0.15+0.15 = 3.30m
C/C length of short wall = 3.30 m
Total centre line length of all walls =
2( 4.30+3.30) = 15.20 m