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
On exterior masonry walls, vinyl enamel most often used on swimming pools, works with great success. 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, use a sodium silicate based concrete sealer that locks out moisture, which is usually the cause of flaking.
Read From the Ground Up: Foundations
, to learn more about building proper foundations