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Plastering Sand Calculator

Calculate fine washed sand and cement for internal wall plastering (12mm), external roughcast (15–20mm), and ceilings (6mm).

Plastering Materials

Real-Time
Plaster Sand Volume
0.00 m³
0 CFT
Cement Bags (50kg)
0 Bags
0 kg cement
Sand Weight
0.00 T
Fine washed sand
Dry Volume Required
0.00 m³
Includes 1.33 dry factor + waste
Visual Engineering

2-Coat Wall Plastering Strata

12mm coarse scratch coat with scored mechanical keying + 3mm fine skim coat.

BRICK CORE 12mm 3mm PLASTERING MATHEMATICS • Vol = Area (m²) × Thickness (m) • Dry Factor: 1.33 × Wet Vol • Waste / Key Raking: +15% • Sand Ratio: 1:3 to 1:4 Fine Sand

2-Coat Wall Plastering Strata

12mm coarse scratch coat with scored mechanical keying + 3mm fine skim coat.

Mathematical Theory

Engineering Calculations & Formulas

Mathematical formulas and engineering constants powering this calculator.

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Plaster Volume Formula

Direct volume calculation accounting for 12mm / 15mm / 20mm depths.

Plaster m³ = Wall Area (m²) × (Depth mm / 1000)
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Dry Mix Multiplier

Standard mortar dry shrinkage factor of 1.33.

Dry Material = Wet Volume × 1.33 × (1 + Waste 15%)
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Fine Sand Proportion

Exact cubic feet and tonnes of washed plastering sand required.

Sand CFT = Dry Vol (m³) × 35.315 × (Sand Parts / Total Parts)

Standard Wall Plastering Thicknesses

  • 6mm (1/4 inch): Concrete ceiling smooth finish.
  • 12mm (1/2 inch): Standard internal brick and block wall finish (1:4 or 1:5).
  • 15–20mm (5/8 to 3/4 inch): Exterior roughcast or 2-coat scratch + finish rendering.

Always account for 15–20% extra volume because mortar penetrates the uneven raked masonry joints and surface roughness.

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