Warning Signs Before You Coat
- Efflorescence (white crystalline residue) on the slab
- Dark patches that never fully dry
- Musty odor in a closed room
- Previous coating that lifted in bubbles or blisters
How We Test
Calcium chloride tests and relative-humidity probes measure moisture vapor emission over 24–72 hours. Plastic-sheet taped down overnight is a rough field indicator we use during estimates.
What the Numbers Mean
Vapor emission rates above roughly 3 lbs / 1,000 sq ft / 24 hr require a moisture-mitigating primer. Above roughly 6 lbs, we recommend investigating the moisture source before installing anything.
Fixing the Cause vs Covering It
A vapor primer is not a repair for active leaks, poor grading, or missing vapor barriers. If water is entering from outside the slab, that has to be corrected first — the coating cannot dam it.