The cost estimation of any construction work is done by various methods. By using the cost estimation methods we get approximate value of estimate. The quantity calculated in estimate is nearly exact as per execution of project.
The use of these methods are basically depends upon the design type and shape of structure we are estimating i.e. circular, rectangular, frame etc. In simple word, how simple to estimate a project is applicable type of method.
Cost Estimation Methods in Construction work
These are most commonly used
- LONG WALL SHORT WALL METHOD
- CENTER LINE METHOD
- CROSSING METHOD
- BAY FRAME METHOD
- SERVICE UNIT METHOD
LONG WALL SHORT WALL METHOD:
This cost estimation methods is also known as out to out and in to in method.
In this type of estimation of building, the longer wall is calculated and measured and same for shorter wall.
This method of estimation is most commonly used in PWD(Public Work Department) because it is practically most easy and accurate method in any circumstances.
Example of long wall and short wall method of estimation:
Suppose we have to estimate boundary of a plot 20×30 m, Its wall size is 0.46 m in width and 2.00 metre in height.
Then estimation is:
- Long wall = 2x30x0.46×2.00 = 55.20 m3
- Short wall = 2x(20-2×0.46)x0.46×2.00 = 35.11 m3
- TOTAL = 55.20+35.11 = 90.31 cubic metre of brick mesonry
CENTER LINE METHOD:
Center line method is basically a length line in the center of structure, which cover the side length of structure also.
This is most commonly used in closed boundary structure like circle, rectangle. This is not easy to find exact center of line in practical so their may be a presence of error in actual calculation.
Example of center line method
- Suppose we have to find circular boundary of a well whose radius is 2.5 metres
- Then estimation is taken by the center of wall i.e. outer face of wall minus half of wall
- Total Length = 2×3.14x(2.5-0.23) = 14.2556 m
- Total volume = 14.2556×0.46×2.00 = 13.115 cubic metres
This method is nothing but used the similar concept of center line method. In this method of estimation the room size plus width of wall is used in calculation.
If any building having more number of floor in similar manner then a single bay is estimated and multiplied by a number of bay frame structure. This also used in a single floor if their are similar structure in frame.
SERVICE UNIT METHOD:
If the structure have a number of multiple structure with similar size and shape then a structure is estimated and multiplied in a number available.
This method is also applicable for the use of unit material in a building covering a specific area. so It is based on a single to multiple unit of items.
Like we have a building, chair, bed, fan etc.