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.
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. The accuracy considered in preparing an estimate is based on the unit of payment and the rate of the item.
Nonetheless, taking dimensions to nearest 1 to 0.5 cm may be permitted for practical reasons. on the other hand, extreme accuracy is not needed if rates are low and paid for % to ‰ unit.
In contrary, the width and thickness of the wall must be measured with great accuracy. 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. 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