Foam Insulation 1970 or earlier

I inspected a home last Friday that was built in 1900. The owners have lived there 40 years. I found what I think is a foam insulation in the attic and in the floor system in the basement. This material is about 5 to 6 inches thick and when I touch it the material turns to dust. I tried to lift a bit of it out near the attic hatch, it is very light and soft and chunks up a bit but still basically turns to dust, almost like powder. This same material found in floor joists in basement, except that a black cardboard material is between joists and stapled to joists holding the foam type material in place. The material in basement breaks down the same as that in the attic. I’ve never seen any thing like this before. The owners state that this material installed prior to their purchase 40 years ago. Need help identifing this material. Also did this material breakdown over the years and I would assume that the R-Value is pretty close to nothing. The owners added a reflective foil insulation over this material in the attic.





hard to tell from Pic # 1
Pic # 2
Looks like UFFI

I would agree. I have the same material in my house and balloon framing to go with it. The stuff may have been good when first installed but if you do any remodeling, it goes everywhere. Light and fluffy is right. If I do any work inside, I get suited up and wear a mask.