Who to Calculate the Quantity of Cement and Sand in Plaster

How to calculate cement, sand quantity for Plastering?

Before beginning to work on the plastering calculation, note down these general things

·         Cement Mortar Ratio for wall plastering 1:6

·         Cement Mortar Ratio for ceiling plastering 1:4

·         Plastering thickness should not be more than 12-15 mm. If there is a need for an additional coat don’t do that at one go.

·         Ensure you are using good quality of cement & Sand (In silt content test, we have discussed how bad sand quality affects the work)

·         Also, ensure you are using measuring box (not head pan) for site mix ( Here is the basic construction tools list)

·         Please do read the plastering checklist post for the complete list.

Plastering Work Ratio Calculation

For a better understanding, we are going to do this calculation for 100 Sq.m area.

To calculate the cement and sand for 100 m² plastering area in 1:6 ratio and 12 mm thickness.

Cement Mortar Required:

Plastering thickness 12 mm            = 12/1000 = 0.012m

Volume of cement mortar required = ( Plastering Area x thickness )

                                                         = 100 m² x 0.012m = 1.2 m³

(This is wet volume that means we need this much volume of cement mortar after mixing water, So for dry volume, we have to add 30-35% as bulkage of sand, we are using 35% and wastage as 20%)

Consider 35% Sand Bulkage     = 1.2 m³ x (1+0.2+0.35) (Many of us would use 1.54 as constant)

                                                   = 1.86 m³

              Cement : Sand (Ratio) = 1 : 6 ( Total = 1+6 = 7 Parts )

                  Cement required (1 Part) = 1.86 x 1/7

                                                                = 0.265 m³ /0.0347

                                                                = 7.66 bags (Approx – 8 Bags)

                        Sand required (5 Part) = 1.86 x 6/7

                                                                = 1.59 m³