DIY Home Improvement, Remodeling & Repair Forum

DIY Home Improvement, Remodeling & Repair Forum (
-   Insulation and Radiant Barriers (
-   -   Unidentified insulation: What is this? (

Msupsic 06-24-2010 03:24 PM

Unidentified insulation: What is this?
4 Attachment(s)
I am doing some work in our garage, rebuilding the walls, etc. I came across this yellow-brown insulation inside the walls. It is a rigid, slightly spongy board-like material. See the first two photos.

This particular space between the studs is also a return for the heating system. Apparently it was common in old homes, to use the empty space between studs as air ducts. So I am slightly concerned that this material could be flowing through our HVAC system. The fuzzy gray stuff in the close-up is lint that has collected over the years.

A few hours later I noticed that there is a shaggy brown sheet of insulation hanging off of one of the heating ducts in the basement. See the last two pics.

Does anyone have any idea what these substances are, and if they’re dangerous? I was reading that it could be cellulose board, rock wool or slag wool, which are not dangerous. But could it possibly be Vermiculite, which contains asbestos?

Any advice would be appreciated. Thanks!

Msupsic 07-06-2010 02:08 PM

May be on to something...
I had a home inspector look at the first two images, they seem to think this material is a harmless cellulose wallboard, used to insulate from heat loss inside the return duct.

Regarding the second, fuzzy material: I came across more of this in the garage, covering the heating ducts. It is placed between both sides of the duct and the surrounding walls.

I was doing a little research and found a similar material called Thermalam, a woven, mesh-like fiber material with the same basket-weave pattern. It is used to dampen noise on expanding heating ducts.

Do you think there is a possibility that this material was used to dampen noise from expanding ducts? It seems to make sense, as it is placed in locations where a duct could rub or knock.

All times are GMT -6. The time now is 11:57 AM.