White cottony growth on basement wall mold or mineral deposits?
That white, cotton-like substance appearing on basement walls near historical water damage is likely either mold or efflorescence, which are mineral salt deposits left behind by evaporating water. Because it looks fluffy or cottony, it's difficult to tell at a glance whether you are dealing with a harmful biological growth or harmless minerals, leaving homeowners uncertain about how to clean or treat the wall.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Scrubbing the wall and fixing water issues
- 2Installing drain tile
- 3Putting a new cover over the door to prevent water from creeping in
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“White and cotton-y. Mold?”source ↗
“Wondering about this found in basement near bilco door opening, there has been historical water damage on the boards but wondering about the new white appearing. Wondering if it’s mold:”source ↗
Where this came up
People with this problem also raised
- 2Brownish goo coming out of gap behind bathroom sink
- 3Why is this wall discolored if it is not wet?
- 3How to find and handle hidden mold behind walls
- 2Why are my bathroom walls wet and brown after a shower?
- 3Why is my basement wall paint peeling and turning white?
- 10How to clean mold on drywall or know when to cut it out