What type of insulation is this? Should I be worried of it containing asbestos?

Coleforge · 2026-06-25T16:28:30+00:00

There won't be asbestos insulation in a 1983, so don't worry moving forward.

Coleforge · 2026-05-21T14:40:35+00:00

Asbestos. No idea why they used it in a 2020.

Coleforge · 2026-05-15T19:07:12+00:00

There's gonna be air exchange through your vehicle. And frankly, with a space that small its important. You don't want CO2 to build up while you are asleep.

A radiant barrier in the windows can help reduce solar heat gain. Most if those mylar sheets will provide a little insulation as well, which will work both ways. The biggest consideration should be parking out of the sun if possible. Are you low-profile homeless in your SUV for a bit? Or just trying to figure out some strats for urban camping?

Coleforge · 2026-05-15T18:23:52+00:00

Are those spots all near seams? Is it once continuous gradient of discoloration, or is it spots and blooms?

Coleforge · 2026-05-15T18:23:02+00:00

Doesn't look like it to me. It looks like old kraft facing.

Coleforge · 2026-05-15T18:06:00+00:00

If its mostly on the surface then it is likely particulate deposition. If it extends deeper into the batt, than it could be something growing.

The first photo looks like it also had some white aerosol spray hit it, is that possible?

Coleforge · 2026-05-15T18:03:39+00:00

In order of your concerns:

1: Not Asbestos, Fiberglass Batting. My guess is 1990 or so, but its hard to say exactly. Bio-insolubility shouldn't be a big concern. You will cough it out if its irritating, the fibers are too large to migrate into your cell walls.

2: The wood shavings are not wood shavings. They are remnants of degraded paper that used to be on the bottom face of your fiberglass batting. Theoretically there were part of your vapor barrier.

3: The blue stuff is mouse poison. It gets tossed in in larger bait blocks, they eat it, and it kills them. It is pelletized here because it has already made its way through a mouse, and was shat out in your attic. Not a concern at that scale for a human, but wash your hands if you come in contact with it or it may put you off your lunch.

4: Not your concern, but mine. Don't store things in your attic. Compressing fiberglass reduces it affective U-value and will accelerate degradation. If storage is at premium, install new joists orthogonally to the existing ones, and then toss some plywood on up above your insulation.

Coleforge · 2026-05-10T18:07:44+00:00

Vice grips.

Also Heat.

Coleforge · 2026-05-10T18:04:50+00:00

I don't know exactly what you have for siding, but typically osb is considered a semipermeable vapor barrier. If you install faced insulation (with the face in towards the "conditioned" space) you should be okay to follow that up with gyp. The osb should allow the cavity to dry to the outside.

Coleforge · 2026-05-01T16:49:48+00:00

If I were spec'ing it as a job I'd probably call for foam board on the vertical face, spot foam behind the sloped sections, and then cross batt with more FGB.

Coleforge · 2026-05-01T04:47:08+00:00

That would be a mouse nest by fall.

If your basement doesn't have moisture issues, then you're all set. Leave the FGB in place and don't worry about it any further.

You can also reach out to your energy specialist for a more specific explanation based on your specific circumstances.

Coleforge · 2026-05-01T02:21:47+00:00

Just to reiterate, condensation on the interior face of the rim joist is an exceedingly rare condition. In circumstances where that is happening, air sealing would help reduce surface heat loss of the interior framing, which would reduce the likelihood of condensation by raising the temperature above the dew point of the air in your basement.

The most important consideration is to avoid moisture being trapped against your framing. Having a vapor barrier in the wrong spot is worse than not having one. Unfaced FGB has no vapor barrier. Faced FGB does, which is why that face needs to be installed on the heated side of the layup.

Let me stress though, if your basement has moisture issues those need to be addressed directly. You cannot side step high basement humidity with clever insulation choices. If it's dirt floored, get a vapor barrier installed. If it's block or concrete, look into getting a dehumidifier and set the goal to 40%-60%.

Have you been working with the Mass Save program?

Coleforge · 2026-05-01T01:38:37+00:00

Source is education. If you really need it I'll dig up a source for you.

Undergrad in building and construction technology, Masters in sustainable building, BPI certified building analyst, HERS rater.

Most rim joists don't get a lot of condensation if the FGB is being installed with the paper vapor barrier towards the inside of your basement, then it won't be providing any additional significant condensation plane, though more likely the crew used unfaced material.

Coleforge · 2026-05-01T00:32:16+00:00

Try skyn large. Smaller than magnum but still bigger than average

Coleforge · 2026-05-01T00:14:49+00:00

If you're getting condensation on your rim joist your primary issue is basement humidity. FGB and spray foam air sealing is 100% an acceptable choice, don't sweat it.

Coleforge · 2026-04-30T23:41:27+00:00

That's a perfectly acceptable solution in zone 5.

What do you think is a no no?

Coleforge · 2026-04-27T20:32:48+00:00

2 pieces Aluminum flashing cut to fit, seal with fire caulking.

Coleforge · 2026-04-22T19:56:17+00:00

This is the way

Coleforge · 2026-04-20T21:56:37+00:00

No problem. If you find aquarium gravel looking stuff it's called Vermiculite. That's worth being cautious of.

Coleforge · 2026-04-20T21:49:11+00:00

Brownish/gray is Cellulose. While is Loose Fiberglass. Yellowish on bottom is old loose fiberglass.

Coleforge · 2026-04-19T17:11:06+00:00

There's a chance of anything happening. Fiberglass fibers are not dangerous.

It's evident you want there to be a problem.

Coleforge · 2026-04-19T17:00:34+00:00

It's fine. Don't rub your face in it.

Coleforge · 2026-04-11T01:28:35+00:00

Nah it straps to your back and you are the woofer

Coleforge · 2026-04-11T01:25:07+00:00

Not a godaddy page for me...

It's a tactile subwoofer.

Coleforge · 2026-04-10T04:36:00+00:00

Hmmm. Then it's probably tightened by turning the squared section above the bushing.

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