On Sun, 27 Jan 2013 21:11:47 -0800 (PST), wrote:

Dear Readers,
Today I was removing kraft-paper-faced fiberglass bats from between the rafters behind my kneewall (cape cod house). They were draft with no signs of water stains. When I pulled the fiberglass bats away from the roof deck, there was frost on the roof deck and some frost on the bat as well (25 deg was high temp today). I've no idea how many years this may have been happening. I let it dry, but looked like mold so I sprayed Tilex (chlorine bleach & water mixture). After it dried, some of the white stains disappeared, but the dark stains still remain. Is this just stained wood, or ??? I can't imagine mold living after Tilex.

Before
http://i899.photobucket.com/albums/a...psb30b76b6.jpg

After
http://i899.photobucket.com/albums/a...psb0c50e0b.jpg

Comments appreciated.
Regards,
Theodore
Wait and see what it looks like when it is fully dry. Doesn't really
look like mould to me from here. Looks like wet wood - possibly with a
bit of rot? Is it soft where it is dark????