External plaster area = building perimeter × height (with parapet) − openings. A 60 m perimeter, 7 m high facade with 50 m² of openings is 370 m². In two coats (12 mm of 1:4 and 8 mm of 1:6) that needs about 48 bags of cement and 7.7 m³ of sand.
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Scaffold ≈ (perimeter + 8 × 1.2 m for corner platforms) × height = 487.2 m²
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Generated with myconstructioncalculator.com. Estimates for planning and ordering only; verify against drawings and specifications.
Formula
Area = perimeter × height − openingsEach coat = area × thickness → × 1.27 dry → cement and sand by its mixScaffold ≈ (perimeter + 8 × 1.2 m) × height
Worked Example
60 m perimeter, 7 m high, 50 m² of openings, 12 mm of 1:4 + 8 mm of 1:6:
Area = 420 − 50 = 370 m²
Base coat: 4.44 m³ wet → 32.5 bags, 4.5 m³ sand
Finish coat: 2.96 m³ wet → 15.5 bags, 3.2 m³ sand
Total ≈ 48 bags cement, 7.7 m³ sand; scaffold ≈ 487 m²
Common Two-Coat Specifications
Coat
Thickness
Mix
Base (rough)
12–15 mm
1 : 4
Finish
6–8 mm
1 : 5 or 1 : 6
Single coat (sheltered)
15–18 mm
1 : 4
Frequently Asked Questions
How thick is external plaster?
Usually 18–20 mm in two coats, a 12 mm base (rough) coat and a 6–8 mm finish coat, for better crack control and weather resistance.
What mix is used for external plaster?
A richer base coat, often 1:4, with a slightly leaner finish coat such as 1:5 or 1:6, so the finish is never stronger than the coat beneath it.
How much scaffolding is needed for external plaster?
Roughly the facade area plus allowance at corners, about (perimeter + extra for corner platforms) × height. Your scaffold supplier will design the actual layout.
