Basement waterproofing paint calculator
Masonry waterproofing paint (DRYLOK and similar) covers as little as 75 sq ft/gal on rough block — much less than wall paint. Two coats are required to form the waterproof seal. Important: waterproofing paint is for damp / humid surfaces, not for active leaks. Standing water needs structural fixes first.
Estimates round up to the nearest quart and are based on Kompozit's published coverage. Buy slightly more for touch-ups and color changes.
Waterproofing paint vs. real waterproofing
Masonry waterproofing paint handles dampness and minor humidity — the kind of basement that smells damp but doesn\'t actually have water on the floor. For active water intrusion (puddles after rain, weeping seams, hydrostatic pressure forcing water through), you need exterior drainage or interior dimple-mat systems. No paint will hold back hydrostatic pressure.
Why coverage is so low
Waterproofing paints are heavily filled with portland cement and elastomeric resins to plug the pores in masonry. The thick film is what does the work. You\'re buying weight, not coverage area — plan for 2–3× the gallons of regular wall paint.
Stiff brush, force the paint in
Use a stiff masonry brush. Work the paint into the porosity, especially in mortar joints. Roller-only application skips the joints — that\'s where water finds a way through.