In order to calculate the required quantity of cement plastering, we have to follow the following 3 simple steps.

Step 1:-Assumptions

Area of Plaster = 1 m²

Thickness of plaster = 12 mm =0.012 m

Mix Ratio → 1:4

Step 2:- Quantity of Plaster

∵ Volume of plaster = Area of plaster x Thickness of plaster

Volume of plaster = 1 x 0.012=0.012 m³

Add 20% extra Quantity for Filling of joints, Depressions & Wastage

∴Volume of plaster = 0.012 + [ (20×0.012) /100 ] =0.0144 m³

Dry volume of plaster = Wet volume x 1.35

Dry Volume = 0.0144 x 1.35 m = 0.01944 m³

Step 3:- Quantity of Cement

Quantity of Cement = (Dry Volume of plaster x Cement ratio) / (Sum of the ratio)

Quantity of cement = (0.01944 x 1) /(1+4)= 0.003888 m³

∵ Density of Cement = 1440 kg/m³

Weight of Cement = 1440 x 0.003888 = 5.6 Kg

∵ 1 bag of cement contains 50 kg of cement

Number of bags = 5.6 Kg/50 = 0.112 No’s