Coatings Calculator
Specialist coatings - tanking, waterproofing, decking, floor, bitumen, metal, felt & roof
Tick which sizes the product is sold in - the calculator picks the best combination to minimise waste.
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Frequently Asked Questions
How much specialist coating do I need per square metre?
Coverage varies widely by product: Bitumen/tanking paint: 1-3 m²/litre. Epoxy floor coatings: 4-6 m²/litre. Wood preservatives/deck oils: 6-10 m²/litre. Sealers/stabilising solutions: 4-8 m²/litre. Always use the spreading rate from the product data sheet - it varies by substrate and application method.
What is the difference between a primer, sealer and stabilising solution?
Primer: improves adhesion between substrate and topcoat; may also seal porous surfaces. Sealer: penetrates to lock down dusty or powdery surfaces. Stabilising solution: thin penetrating product specifically for crumbling render, plaster or masonry. These terms are sometimes used interchangeably - always read the product data sheet to confirm intended use.
What is tanking slurry and when do I need it?
Tanking slurry is a cementitious waterproofing coating for basements and below-ground walls where hydrostatic pressure pushes water through the structure. Applied internally or externally in two coats at 2-3 kg/m². Approved Document C requires adequate moisture resistance for all habitable below-ground spaces.
How much wood preservative or decking oil do I need?
Smooth planed timber: 6-10 m²/litre. Rough-sawn or textured timber: 4-6 m²/litre. New timber is very absorbent - apply a second coat while the surface is still slightly tacky. Pressure-treated timber should dry for several weeks before oiling. Hardwoods absorb less than softwoods.
Can I apply coatings to damp or wet surfaces?
Most coatings require a dry surface. Exceptions: cementitious tanking slurries can be applied to damp masonry and cure in the presence of moisture. Some epoxy products are formulated for wet-on-wet application. Always check the product data sheet - applying standard coatings to damp surfaces risks blistering, loss of adhesion, and early failure.
How many coats of coating do I need?
Most specialist coatings need minimum two coats. Tanking slurries: two coats applied at 90° to each other for full coverage. Epoxy floors: two to three coats for a seamless finish. Wood oils: apply a third coat on cut ends, knots, and end grain where absorption is highest. Never apply fewer coats than specified - it risks product failure.