Can anyone tell me what this white powder might be? I was ripping up the carpet from my basement when I saw this underneath the padding and on the cement foundation. It's white and cakey.
I at first thought I would just vacuum it up, so I took a wire brush and started rubbing it to break it up into a fine powder so it could be vacuumed. I did that to a portion of it, then I noticed that there is discoloration in the cement underneath the white substance.
It seems that this white powder was probably placed there on purpose to cover up something in the cement. I don't see evidence of a crack there, nor is there cracking anywhere else in the foundation. Could it be mold related? I'm a little nervous to do much else with it until I know what it is. I don't want to undo whatever was done when it was put down.
Best Answer
Looks like effloresence to me, which itself is not harmful, but possibly a symptom, mainly of water movement; I would check perimeter walls for further signs of water infiltration, and make sure water movement outside is properly being handled, i.e. gutters, grading.