Calculate plaster and render quantities for walls and ceilings. Multi-coat support.
Plaster and render coverage depends on the coat thickness, the number of coats, and the background surface. A standard 2mm skim coat of multi-finish covers roughly 10-12 square metres per bag on a flat surface, but a rough block wall will absorb more material. External render typically needs two coats — a scratch coat at 10-12mm and a top coat at 6-8mm. This calculator applies standard coverage rates for each product type and coat thickness, then adds a practical waste allowance. Always check the manufacturer's data sheet for the specific product you are using.
Part of Builder Tools Calculators — construction tools for UK tradespeople.