Inspector's check · Basement and crawlspace
Is any white crust on the foundation walls light and not spreading?
Efflorescence is a white, powdery or crunchy crust left when moisture moving through concrete or block dries and leaves its minerals behind. Some is common, especially in older basements, and on its own it isn't a leak or a flood line. It brushes off dry and dissolves in water; mold smears and smells musty. Brush it off and look again in a few months.
Why it matters
It shows moisture is passing through the wall. A light dusting is mostly cosmetic, but heavy or spreading crust means more water is coming through, usually from drainage outside, and that is cheaper to fix before the basement gets damp.
If it's a problem
An inspector would write it up as “Efflorescence (white mineral crust) on the foundation” and rate it keep an eye on. Your options, with rough U.S. costs:
- DIY (usually best), $0 to $100: Brush it off with a stiff dry brush, then fix the outside: downspouts out 4 to 6 feet, soil sloping away, gutters clear. Run a dehumidifier.
- Handyman, $300 to $900: Improve drainage outside, then apply a masonry water sealer to the clean, dry wall.
- Pro, $3,000 to $12,000: If heavy crust keeps coming back with damp walls, a waterproofing contractor adds interior drainage.
Get this on your own house's plan
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