Black floor convering ? what is it

[AMPICK]

I have repositioned a down stairs toilet and during the excavation i had to got through this 20 mm black material. I am not sure of its purpose other than it could be to match up different floor levels as this is in an extended part of the house. i don't think it is for damp as there is a membrane beneath the 50 mm of concrete floor. The house was built in the 50's and i believe extended in the 60's.

Thank you

 

[masona]

Maybe the dpm has failed because of damp problem so they use the bitumen layer

 

[WoodYouLike]

Masona, I was thinking the same, but stopped short on answering because it seems to be 20mm thick. We only encouter thin layers, but could bitumen be so thick?

 

[masona]

could bitumen be so thick?

Yes, depending what aggregates is use to mix with bitumen such as stone, sand or filler but don't really need 20mm thickness though.

 

[WoodYouLike]

So it was not only used as adhesive, but also as a 'bonding' product (but not anymore I hope)

 

[AMPICK]

I have been asking around, and a valid reason could be that the floor concrete was quickly poored, and not finished smooth. Then this stuff was used to level, and give a smooth finish which was also thermal barrier.

There is what appears to be a course fibre glass looking mat was laid onto the concrete before the covering was applied.

Thanks for the responses