Black textured board under insulation?

Haven’t come across this yet and I am having trouble identifying it…any ideas? It is all over the attic throughout underneath the blown cellulose.

Might be “TenTest” sheeting, but I’ve never seen it used in the attic, just on the exterior.

Might have been a flat roof at one time.

I agree it looks like an old flat roof. Was the material hard or soft?

The texture of the material was firm but was sponge like when probed with screwdriver. The edge of the material looks compressed, felt like with an asphalt type composition. The house was built in 1950. The current roof is gable type, with 2-3 asphalt shingle layers. The material in question appears to be through out the attic, attached to the underlayment. Hard to say for sure as cellulose is blown over the entire attic area.

Is it hard or soft/fibrous?
Is that tar on top or charring?

My thought as well… looks like charred wood with a tar like substance applied to cover the damage/smell, and the tar has settled into the charring from the high attic temps.

Probably Celotex


It was a flat roof before.

One other Note, if it is celotex or similar I would put it the report that it’s not going to support a persons weight walking the attic.

That would be my guess


What is this guess based on?

The photos…