Painting Concrete Block Foundation
What's the best product to use?
Q: Our concrete block foundation has been painted in the past, both inside and outside. Now it's flaking. What should I repaint it with?
— Bonita, Minneapolis, MN
Steve Thomas replies: On exterior masonry walls, I have had great luck with the vinyl enamel most often used on swimming pools. My friend and painter of 15 years, Peter Speridakos, first suggested this for my chimney when we painted the house six years ago, and where he applied it to unpainted brick it has held up perfectly. On previously painted surfaces, ideally you should sandblast to remove all paint. Where this is not practical, power wash to remove any flaking paint, wash with trisodium phospate, rinse, allow to dry, then paint with vinyl enamel. On interior masonry surfaces I have had great luck with a sodium silicate based concrete sealer that locks out moisture, which is usually the cause of flaking.