The degree of accuracy used in the estimation of various material quantities used in the construction is crucial. This is to prevent cost estimate errors due to lack of proper accuracy and time consuming because of considering great accuracy which is not practical.
Degree of Accuracy in Estimating Construction Works
The accuracy considered in preparing
an estimate is based on the unit of payment and the rate of the item. The higher
the rates the greater should be the accuracy with which the quantities are
computed. The dimensions need to be absolutely correct If the rates are high
and payments are per unit.
Nonetheless, taking dimensions to nearest
1 to 0.5 cm may be permitted for practical reasons. However, extreme accuracy is
not needed if rates are low and paid for % to ‰ unit.
Reduction or subtraction of a few centimeter
to length or height of a wall where masonry is paid per cubic meter would not
make great difference. In contrary, the width and thickness of the wall must be
measured with great accuracy. This is because half centimeter or quarter
centimeter would affect the result significantly. Table 1 provides general
approximation for various measurements and construction items.
Table 1 Degree of Accuracy for Various
Measurements and Construction Works
| Items | Degree of Accuracy |
| Dimensions | Measured to the nearest 1 cm or 0.01 m |
| Areas | Computed to the nearest 0.01 square meter |
| Cubic | Calculated to the nearest 0.01 cubic meter |
| Thickness of slab | Measured to the nearest 0.5 centimeter or 0.005 meter |
| Partitions | Measured to the nearest 0.5 centimeter or 0.005 meter |
| Sectional dimensions of columns, pillars, and beams | Measured to the nearest 0.5 centimeter or 0.005 meter |