Has anyone seen something like this white powder on a crawlspace girder?
Curious what it is, and what a possible cause would be. Crawlspace is connected to a basement. Home is 107 years old. Crawlspace is humid.
Thanks for any insight. Bill
How humid is the crawl space .A reading please !!!. Is the basement humid . Reading please
Is it vented to the out side . What is the humidity reading out side .
Do they have a dehumidifier, is it running, how is it drained .
No idea what the white stuff is looks like some one just threw it around in various areas .
Could be any of at least 4 things, IMO
(1) Mold
(2) Insecticide
(3) Efflorescence
(4) Lime
…
Great to know you have my “6”, my friend! 
Hey folks thanks for the input. I didn’t get a humidity reading so I don’t have that data.
The crawlspace being attached to the basement is not vented. There is a washer and dryer in the basement that are the main cause of the humidity down there.
I thought about insecticide dust but the homeowner said it isn’t and it was isolated to that area.
Sometime mysteries don’t get solved.
The mystery is solved if the homeowner knows for sure it isnt’ insecticide dust. It’s mold. The only mystery is what’s causing the moisture, which isn’t a great mystery, either.
No venting, no vapor barrier on crawl space dirt floor, and the washer/dryer are all contributing factors.
If it was isolated in a high humidity space why would it be mold?
Makes more sense dust or it would be all over the place.
The mystery is why does the seller’s words hold so much weight.
I would tend to not believe (or at a minimum suspect) his prejudiced “facts”.
Looks like some sort of splatter to me. Consistent with a cement or plaster mix.
I would be careful making a statement Like its Mold ,Unless you got some proof .
Little errors can some times come back to haunt us .
It may be.
Hi Brad! :mrgreen:
Did you touch it(with gloves) or at least scrap a little off to check the consistency of the powder?
I’d bet it is lime dust for bugs like fleas…
I did scrape a little off to see the consistency. White powder is what it looks like.
It was isolated to the beams in this area, nothing on the ground or anything else. My report has noted it’s presence and no definitive determination of what it is or why it’s there without further testing etc.
I’m interested too!