Waterproofing Membrane Quantity Calculator
Estimate membrane rolls or liquid waterproofing quantity while keeping coverage, overlaps, coats and project waste explicit. The result separates waterproofed area from purchased material.
Waterproofing system inputs
Waterproofing material requirement
How membrane quantity is estimated
Sheet membranes are purchased as physical rolls, so overlap reduces the effective area each roll provides. Liquid systems are normally estimated from a manufacturer coverage or consumption rate.
Roll count = ceiling(planning area ÷ roll area)
Liquid quantity = surface area × coats ÷ coverage × (1 + waste)
Worked example for sheet membrane
For 180 m², a 10% overlap and 5% waste allowance, the planning area is greater than the nominal 180 m². A 1 × 20 m roll contains 20 m² nominal area, but the effective coverage is lower after installation allowances.
Liquid membrane
Liquid systems should normally use the manufacturer's coverage or consumption figure for the intended dry-film thickness and coat system. Surface texture and application conditions can change practical consumption.
Details can dominate
Upstands, penetrations, corners and changes in plane may require additional detailing materials that are not captured by a simple area-based membrane estimate.
Important limitations
This is a material takeoff tool. It does not design waterproofing details, drainage, substrate preparation, movement joints or system compatibility.
Frequently Asked Questions
Does overlap increase membrane quantity?
Yes.
Can I calculate liquid membrane?
Yes.
Does roll size matter?
Yes.
Are corners and penetrations included?
Only indirectly through your allowances.