In this article, we discuss the Cement Mortar ( Cement + Sand ) Calculation for Plastering work
Check the previous Articles, we discussed the Calculation of the materials for Concrete, Mortar, Calculation of Staircase Slope and Brickwork materials Calculation.
Before go that, we should know some basics about plastering work and plaster
Qualities Of A Good Plaster
- Workability
- Adherence
- Appearance
- Durability
- Atmospheric Agencies
- Smooth And Even Surface
- Shrinkage And Cracking
- Insulation
For more in-depth information about plastering, Check this Article Details About Plastering
The thickness of plastering work
Finishing coats ( and single-coat work, where employed ) shall be of such minimum thickness as just to provide a sufficient body of material to harden satisfactorily under the site conditions in any particular case.
The total thickness of two-coat work exclusive of keys or dubbing out shall be generally about, but shall not normally exceed 20 mm and it shall not exceed 15 mm in the case of in situ concrete soffits. The thickness of three-coat work shall be about, but shall not normally exceed 25 mm.
The thickness of plastering work on an individual coat shall generally be as recommended in the;
| Number of coats and situation | Mix Ratio | Thickness |
|---|---|---|
| Single-coat plaster ( Both internal and external ) | 1:3, 1:4, 1:6 | 10 to 15 mm |
| Two-coat plaster: a) Backing coat ( Both internal and external ) | 1:3, 1:4, 1:6 | 10 to 12 mm |
| Two-coat plaster: b) Finishing coat ( Both internal and external ) | 1:3, 1:4, 1:6 | 3 to 8 mm |
| Three-coat plaster: a) Base coat ( Very rough surface; both internal and external ) | 1:3, 1:4, 1:6 | 10 to 15 mm |
| Three-coat plaster: b) Second coat ( Very rough surface; both internal and external ) | 1:3, 1:4, 1:6 | 3 to 8 mm |
| Three-coat plaster: c) Finishing coat ( Very rough surface; both internal and external ) | Fat lime and fine sand or marble dust in equal proportions | 3 to 5 mm |
Refer to Table-2 ( Recommended plaster specifications ) in IS 1661: 1972 Practice for the application of cement and cement lime plaster finish
Cement and sand calculation for plastering work
Assume that we calculate the 100 m2 area of plastering work with a thickness of 15 mm and a Ratio of 1:3
= 100 X 0.015 = 1.5 m3
Requirement of mortar volume = 1.5 m3
Now, find the cement and sand quantity for a 1.5 m3 Cement mortar with a ratio of CM 1:3
Wet volume = 1.5 m3
Dry Volume = 1.33 x Wet volume
= 1.33 x 1.5 m3
Total required volume = 1.995 ~ 2 m3
Refer to this article for what is Wet volume and dry volume and why 1.33 is used for mortar.
CM 1:3 = Cement Mortar 1:3 ( Cement: Fine aggregate )
Cement calculation
= ( ( Part of Cement ) / ( Sum of Ratio ) ) x Total Volume Required
Part of cement = 1
Sum of ratio = (1+3) = 4
= (1/4) x 2 = 0.5 m3
Unit weight of cement = 1440 kg/m3
= 0.5 x 1440 = 720 kg
= 720 / 50 (1 bag cement = 50kg)
= 14.4 bags of cement required
Fine Aggregate calculation
= ( (Part of Fine Aggregate) / (Sum of Ratio) ) x Total Volume Required
Part of Fine Aggregate = 3
Sum of ratio = (1+1) = 4
= (3/4) x 2 = 1.5 m3
Unit weight of F.A = 1600 to 1840 kg/m3
take 1600= 1.5 x 1600 = 2400 kg
Water required
Assume water-cement ratio = 0.50 (50% of cement)
= 720 x 0.50
= 360 kg
= 360 litres
Summary
Material required for 100 m2 area of plastering work with a thickness of 15 mm and a Ratio of 1:3
- Cement = 14.4 bags (1 bag is 50kg)
- Fine aggregate = 2400 kg
- Water = 360 litre
Plastering materials calculator for quick and time-saving calculation ” Click Here “
practical example
To find the plastering work materials quantity for the given room, Height = 10 m
Wall 1 and Wall 3 = 2 x (1m x 10m) = 20 m2
Wall 2 and Wall 4 = 2 x (2m x 10m) = 40 m2
Total area = 20+40 = 60m2
Plaster Thickness = 15mm, Ratio = CM 1:6
= 60 x 0.015
= 0.9 m3
Find the cement and sand quantity for a 0.9 m3 Cement mortar with a ratio of CM 1:6
Wet volume = 0.9 m3
Dry Volume = 1.33 x Wet volume
= 1.33 x 0.9 m3
Total required volume = 1.197 ~ 1.2 m3
Refer to this article for what is Wet volume and dry volume and why 1.33 is used for mortar.
CM 1:6 = Cement Mortar 1:6 ( Cement: Fine aggregate )
Cement calculation
= ( ( Part of Cement ) / ( Sum of Ratio ) ) x Total Volume Required
Part of cement = 1
Sum of ratio = (1+6) = 7
= (1/7) x 1.2 = 0.17 m3
Unit weight of cement = 1440 kg/m3
= 0.17 x 1440 = 245 kg
= 245 / 50 (1 bag cement = 50kg)
= 4.9 bags of cement required
Fine Aggregate
= ( ( Part of Fine Aggregate ) / ( Sum of Ratio ) ) x Total Volume Required
Part of Fine Aggregate = 6
Sum of ratio = (1+6) = 7
= (6/7) x 1.2 = 1.03 m3
Unit weight of F.A = 1600 to 1840 kg/m3
take 1600= 1.03 x 1600 = 1632 kg
Cement Mortar Materials Calculator ( Cement, Fine aggregate, and Water. ) – ” Click Here “
Water
Assume water-cement ratio = 0.50 (50% of cement)
= 245 x 0.50
= 122.5 kg
= 122.5 litres
calculate cement and sand quantity for plastering work
Summary
Material required for 60 m2 area of plastering work with a thickness of 15 mm and a Ratio of 1:6
- Cement = 4.9 bags (1 bag is 50kg)
- Fine aggregate = 1632 kg
- Water = 122.5 litre
Plastering materials calculator for quick and time-saving calculation
A separate article for cement mortar calculation, Refer Materials Required For 1m3 Cement Mortar In All Design Mix
Note
- Add 5 to 15% wastage (optional, if required then you can add wastage)
- The above plastering work values are changed. If the quantity and quality of material change or the unit weight change
- The water-cement ratio depends on the requirement of strength and workability (not the same for all requirements)