Do I Need to Replace the Insulation Under Bedroom Floorboards?

Question

We recently purchased and moved into a house built in 1943. It is a Cape Cod with a former-attic second floor that seems to have been added on in the 70s

The wood paneled bedroom up there had very gross carpet, which we pulled up. Under the carpet were stained sheets of MDF, then under that was vinyl adhesive, and then under the adhesive was finally the wood planks of the bare floor.

There is an odd bit of this flooring that seems cut out and has some unintelligible wording written on it. Wood panels here are loose and underneath is some pretty old looking gray insulation. I have to assume this insulation runs throughout the whole room under the floor.

The question is, should this insulation be replaced? Should we rip all of this subfloor up to get to it and replace it? And if we don't do that, will there be any hazard to our health or to the house in the long run to have that old insulation up there under the subfloor?

Answer 1

It's very likely cellulose fiber (recycled newspaper treated against fire and bugs) insulation. With the tiny picture I can't quite tell if it is board-type (Homasote®) or loose fill that isn't very full. Or it could be a thin layer (not filling the floor space) of mineral wool/rockwool.

There should be no reason to replace it if so.

If you're feeling paranoid, sure, send a sample to an asbestos lab, which is the only way you can rule that in or out 100%. But asbestos is not particularly hazardous if you don't disturb it and put fibers in the air.