What is that white chalky substance on the walls of my basement or crawl space?
This substance is called efflorescence. It is the mineral deposits left behind on the surface of the concrete, brick or mortar after water has passed through them, and then evaporated. It appears as a white powder or crystals. It is sometimes confused with mold, but it is not aliveit is just mineral residue. It is not harmful and can be swept or brushed off. But it is a sign of water infiltrating (probably slowly) through the wall or floor. Our licensed inspectors are trained to notice these signs and relate the source of your water issues in an understandable way so you know what treatment is best for your situation.