Before you paint / Concrete & floor coatings
Can you coat a damp garage floor?
A dry-looking floor tells you only so much. Check what is happening in the concrete before choosing a coating.
If you see damp patches, pause before coating. Moisture needs a closer look, even when the rest of the floor looks dry.
Dry on top does not tell the whole story.
Moisture can move through concrete from below. Excess moisture can cause a coating to fail, so appearance alone cannot tell you whether the floor is suitable. The coating you choose has its own testing requirements and moisture limits.
A plastic sheet is only a first check.
The podcast discusses checking for moisture beneath plastic. Condensation under the sheet is a reason to investigate further. Even without condensation, the floor may still be too damp to coat.
Corotech’s preparation guide describes this as a minimum check and discusses additional measurement. Follow the testing method required for the product you plan to use.
If you find moisture, get the floor evaluated.
Benjamin Moore recommends a professional when a garage floor has moisture problems. The next step depends on the source and amount of moisture, any existing finish, and the proposed coating. Those details need checking before choosing a product or a repair.
The episode describes moisture-related peeling that can turn into repeat work:
“Now you’ve got a project every summer.”
Home In Progress, episode 315 · 11:10
Return to the guide for the rest of the questions to ask before you coat.
Sources
Home In Progress, episode 315
June 24, 2023 · Moisture discussion at 09:13 to 11:16
Corotech preparation guide, printed page 2
Benjamin Moore garage-floor guide