Strange White Substance in Attic

Please, can anyone identify what’s going on with this decking? It appeared and wiped away much like a thick layer of efflorescence, but it’s on wood. Kind of powdery, and as you can hopefully tell from the pictures, is not spotty like mold, it covers complete board. Note that this attic was improperly ventilated. Any ideas?

Test it

I’d be willing to bet what ever the substance is, it was on the wood planks before they were installed at roof.

What I think, too…

I agree. A “growth” will not stop at the joint.

Scrap wood, looks like paint.

Mine does!:smiley:

I don’t think anyone wants to know about that. :wink:


Yes. Your growth stops at your neck! lol. :mrgreen:

(just ribbin’ ya, Roy)

Looks like salvaged concrete forms, probably residue from the pour. Don’t waste money on testing.

BTW. That insulation is upside-down or the paper facing needs removed or perforated.

Thanks everyone!