Waterproofing Membrane Calculator — ft, sq ft, cost
How to use this calculator
Select surface type — foundation wall (perimeter × depth), slab/floor, deck/balcony, or enter custom area. Choose membrane type: liquid applied, sheet (peel & stick), drain board, or dimple mat. Results update with membrane quantity, optional primer, seam tape, and cost.
Liquid applied — coverage in ft²/gal at 60 mil DFT.
Sheet membrane — 36″ wide peel & stick rolls, 6″ overlap.
Drain board — 4′×50′ sheets (200 ft²).
Dimple mat — 4′×50′ rolls (200 ft²).
Saved Calculations
| Time | Surface | Area ft² | Type | Qty | Cost |
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How to Calculate Waterproofing Membrane
This calculator estimates membrane quantity for foundation walls, slabs, decks, and custom areas. Choose from liquid applied (coverage ~25 ft²/gal at 60 mil DFT), peel-and-stick sheet membrane (36″ wide rolls with 6″ overlap), drain board, or dimple mat (4′×50′ sheets).
Formulas
Liquid: gallons = area / coverage per gallon. Sheet: rolls = area / (roll width × roll length × effective coverage factor). Drain board / dimple mat: sheets = area / 200 ft². Seam tape: linear feet = number of seams × seam length. Primer: gallons = area / 300.
Application Standards
ASTM D6153 for self-adhered sheet membranes. ICC-ES evaluation reports for liquid membranes. Minimum 60 mil DFT (dry film thickness) for below-grade waterproofing. Two coats recommended for liquid applied systems.
FAQ
Do I need primer? Most peel-and-stick and liquid membranes require primer on concrete surfaces. Check manufacturer specs. Drain board vs dimple mat? Both protect the membrane and facilitate drainage. Drain boards add R-value; dimple mats are more economical.
