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Can you identify this type of insulation?


Does anyone know what type of insulation is in the walls of my old home?

It's light and paper-like. My first impression was that I was pulling out a wasp nest. Close inspection shows it's very fibrous, as you can see in the close up shot.


Re: Can you identify this type of insulation?

My guess would be Rock Wool.

Re: Can you identify this type of insulation?

Great. Thanks!

Good to know my walls aren't chock full of wasp nests!

Re: Can you identify this type of insulation?

Are you sure it's insulation? I admit the tiny photos may be deceiving my eyes, but it looks like twisted fibers of some kind; more like yarn than rockwool. I work with both loose-fill and batt rockwool, and this looks like neither.
There was a type of early cellulose that came pre-wrapped with black paper on both sides. , or just blown in loose. It's characteristic is that it's gray-colored, and over time breaks down to downy powder. It's the lightest, least dense stuff you can run across in walls or ceilings. I have only seen the black paper-wrapped stuff in walls, but the loose fill would be in walls or ceilings.
If it won't burn no matter what, it's rock wool. Fiberglass will burn with MAPP gas, and cellulose will spontaneously combust ... JK!

Re: Can you identify this type of insulation?

Interesting angle. I just tried to burn it with a regular lighter and it burned easily.

It has the appearance of paper in that it's flat. It's super lightweight and airy. You can see the fibers if you look really close. It's layered, brown, gray, brown, gray ... I see nothing to make me think it was newspaper. While repairing a section of wall, I pulled this out from behind the lath. The wall seemed "full" of it. Not packed, but there was a bunch in there.

Seriously, it looks just like wasp paper to me.

Re: Can you identify this type of insulation?

Why would you think the post is a joke? hmmm ....

At first, I bought into the rockwool theory, but searches seem to agree that rockwool is not easily ignitable. My material, however, is.

The Internet is wonderful. But it still disappoints me how simple knowledge like this is hard to come by, even after HOURS of research.

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