Wall/Ceiling Details
Total wall or ceiling area
Add 10-15% for wastage
Coverage: ~6.7 m² per 25kg bag at 3mm (gypsum)
Based on selected coat system yield.
Results
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UKUK Building Regulations
References & Sources
Standards Cited
- BS EN 13914-2 — Design, preparation and application of external rendering and internal plastering — Internal plastering
Defines internal plaster application thicknesses, coat systems, and coverage rates - BS 5492 — Code of practice for internal plastering
Guidance on plaster thickness (2mm skim to 20mm thick coat), coverage rates, and application methods
Formulas Used
- Plaster volume:
volumeM3 = wallArea x (plasterThickness / 1000)
Source: Basic geometry - Plaster weight:
weightKg = wallArea x plasterThickness x materialCoatFactorKgPerMmM2 x (1 + wastage/100)
Source: BS EN 13914-2 — Consumption factor is derived from nominal bag coverage at 10mm for the selected material and coat system - Bags required:
bagsRequired = ceil(totalWeightKg / bagSize)
Source: Standard quantity calculation - Bag coverage:
coverageM2 = bagSizeKg / (thicknessMm x materialCoatFactorKgPerMmM2)
Source: BS 5492 — Coverage varies by both material type (gypsum vs lime) and coat system
Key Assumptions
- Gypsum nominal coverage per 25kg at 10mm: finish 2.0 m2, base 2.5 m2, heavy 2.3 m2 — BS EN 13914-2
- Lime nominal coverage per 25kg at 10mm: finish 1.7 m2, base 1.5 m2, heavy 1.3 m2 (conservative planning values) — BS EN 998-1 / manufacturer data-sheet practice
- If coat system is omitted, calculator infers from thickness: <=3mm finish skim, 4-14mm base undercoat, >=15mm heavy undercoat — BS 5492
- Typical wastage allowance of 10-15% for plaster — Industry standard practice