How to Paint Concrete in Basements for a Moisture Barrier

Scrub the concrete with a wire or stiff-bristle brush to remove loose material and efflorescence (a powdery white substance that often forms on damp masonry.) If there is a lot of efflorescence, scrub it away with muriatic acid or masonry cleaner--follow the label directions for proper mixing and use.

Repair cracks and holes with quick-drying concrete patch. Use the patch to fill in cracks where the wall meets the floor as well, even if you're not painting the floor.

Mix the paint well, both before and during application. Moisture barrier paint is very thick because it has a high solids content, and frequent stirring keeps the solids suspended.

Apply the first coat with a brush. You can also use a roller and brush, rolling small sections and then working the paint well into the surface with a brush while the paint is still wet. Let the paint dry according to label directions.

Paint the second coat using a brush, roller or airless paint sprayer. Apply the paint in a uniform, fairly thick coat.

Check the paint the next time conditions are right for leaking in the basement. If you see any leakage or seeping, wait until it's dry and spot-paint the areas where it leaked. All it takes is a pinhole of missed paint to allow moisture through.