Asphalt/bitumen on basement floor?

[Jompax]

Hello!

Diligent Byggahus reader here, grateful for all the help one can get and find.

I have just torn down framed wooden walls and a wooden floor in the basement of my house from the 1930s. I suspect the walls and floor were added in the 1970s. Under the floor is a thick black carpet-like structure, which I suspect is asphalt or bitumen. However, I have no experience, and when searching the forum, most asphalt pictures seem "thinner." Is there a kind soul who knows and can enlighten me? What can be done to remove it? Try to tear it down myself or bring in help with blasting? Or simply leave it as is?

The floor joists have been directly on the "carpet," which also had a small upturn at the edges around the room. Attaching pictures.

Grateful for your help!

 

[Stefan1972]

Why do you want to remove it then? Does it smell?

 

[Jompax]

We have tiles on the rest of the basement floor, we thought about trying to lay tiles on this part as well. The alternative is some other form of flooring solution over the asphalt (or whatever it is). Gratefully receiving smart ideas though!

 

[Jompax]

Doesn't smell like anything, as far as I can tell.

 

[Jompax]

No kind soul who has seen a similar "mat" before and can inform about what it is and perhaps also how potentially dangerous it is during tearing/removal? As an addition, it can be said that it now actually smells a bit like asphalt/tar.

 

[Rickard.]

It was not uncommon at all to use waterproofing felt similar to roofing felt as an indoor waterproof layer in the past, particularly in larger, more commercial spaces like changing rooms and laundry rooms, but it also appeared in residential bathrooms. If it's used under a wooden floor, the idea was probably as a moisture barrier, which might be somewhat unique, but I'm not sure. If the felt is from the 1930s, it might be coal tar, which is not very healthy, but if it's from the 1970s, it's bitumen and harmless.

Can you cast or use leveling compound over it?

 

[Jompax]

It was not at all uncommon to use waterproofing felt not far from roofing felt as a waterproofing layer indoors in the past, especially common in large more commercial spaces like locker rooms and laundries, but it also occurred in residential bathrooms.
If it's used under a wooden floor, the idea was probably as a moisture barrier, which might be a bit unique, but I don't know. If the felt is from the 30s, it could be coal tar, which is not very healthy, but if it's from the 70s, it's bitumen and harmless.

Can you pour or self-level over it?

Thanks for the response! The room was originally storage for fuel for the boiler according to the 30s drawing. At some point later, it was instead turned into a wooden furnished room, thinking the 70s due to the previous owner's age (now deceased, so unfortunately can't ask). The timber I tore out didn't feel ancient either, had red "mechanical" markings on the short sides, as timber does even now.

It's quite thick, also laid in strips resulting in unevenness where two strips overlap. I think it will be difficult for me to make it look nice with it still there. I'll probably aim to rip it out with a mask on, and try to sand the floor underneath.

 

[Rickard.]

Maybe it's possible to rent a car machine with such a wide chisel,
Not that I've tried, but it's an idea.

 

[Jompax]

Some feedback on how it went, for the sake of it and as a thank you for the help Rickard.

I laminated, rented a dust trap/air cleaner, and created negative pressure using an exhaust. Then I manually tore up the asphalt/roofing felt with a crowbar and bark spade. Exhausting as hell, but it took just a few hours. Now there are small remnants left, but nothing thick. I think I should be able to lay tiles relatively easily on it now.