During routine inspections of basements and crawl spaces across Olympia, Lacey, and Tumwater, homeowners frequently notice a white, chalky, crystalline powder dusting their concrete stem walls. Many panic, assuming their foundation is infested with toxic white mold.
In nearly all cases, this white crust is efflorescence. While efflorescence itself is non-toxic mineral salt, it serves as a glaring visual alarm bell: water is moving freely through your concrete foundation from the exterior earth into your home.
Concrete is porous and behaves like a rigid sponge. When water pools against your foundation from poor drainage or high winter water tables, hydrostatic pressure pushes moisture through the microscopic capillaries of the concrete wall. As this water travels, it dissolves water-soluble minerals—principally calcium hydroxide—within the cement paste.
When the water reaches the dry interior air of your basement or crawl space, it evaporates, leaving behind crystalline calcium carbonate salts. Over years of unmanaged moisture drive, a more serious condition develops: concrete spalling.
As mineral crystals grow inside concrete pores, crystallization pressure expands, fracturing the outer 1/4 to 1/2 inch of concrete paste. This causes concrete to flake, pit, and crumble, eventually exposing interior steel rebar to moisture and corrosive rust. Remediating efflorescence requires resolving exterior water management and applying deep-penetrating crystalline waterproofing barriers.