This is a follow-up to my previous question "Is there a way to determine if cold spots on a thermal image are due to water?"

I cut a small hole in the cold spot in question. The first thing I noticed was a blast of air. This is an external wall, and there are no HVAC ducts nearby - the HVAC was not running anyway. i.e. I assume there is an opening somewhere allowing air and moisture from the outside in.

The area itself had insulation - the backing paper is there, but it seems like much of the fiberglass was chewed up and carried off.

I uploaded an album to imgur with the complete set of pictures I took. I will upload some particular ones here.

There are a number of dead stink bugs, spider webs, and various mouse droppings.

Can you help me understand what the heck these things are in the wall?

  1. bent piece of metal with nail

  2. plastic looking thing with holes, and what may be flashing

  3. more metal with nails

  4. chewed up OSB?

  5. rotting wood with nails, flashing, and chewed up OSB

  6. rotted fiberglass?

Update: I got annoyed enough to cut out a square of drywall:

enter image description here

Notice the bottom left corner - how that "wood like" material is torn up (I did not do that), and there's a tan thing behind it (blue arrow pointing to it)? That's the back of the aluminum siding!

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    I added numbering to the pics to make it easier for everyone to refer to them. I took advantage of the system's ability to automatically number them for us, so don't reorganize the pics or the numbers will all change. Also, if you add more, add them to the end or they'll also renumber automatically. I also took your alt-image text (thanks for including that!) and made it hover text so people can easily see your suspected descriptions by hovering over the pics.
    – FreeMan
    Apr 4, 2022 at 12:11
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    A) Fiberglass doesn't "rot". It may get dirty and nasty, but it won't rot. B) What you're thinking is OSB is probably cellulose insulation. C) The bits of metal look like they could be the remains of an old aluminum window frame. Is there any indication (from odd framing) that there used to be a window here that has since been covered up?
    – FreeMan
    Apr 4, 2022 at 12:15
  • @FreeMan, thank you. I do not know exactly what that black stuff is in picture #6. I cannot rule out the possibility of an old window, but it would be an odd location - this is at ground level of the second floor bedroom / ceiling level of the room below it.
    – negacao
    Apr 4, 2022 at 13:39
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    But: if there did used to be a window there, and it was not properly sealed up - perhaps that accounts for the entrance of moisture/wind/bugs/etc.
    – negacao
    Apr 4, 2022 at 13:40
  • I found what appears to be a very old picture of my house (not 100% positive), showing a window around that location on the first floor. I'm going to poke open the wall there and see if I can see anything.
    – negacao
    Apr 4, 2022 at 13:59

1 Answer 1


It turns out the metal bit pictured here are the back side of the aluminum siding.

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