I've been asked to help out a friend. He is putting in a second upstairs loo and has a single interior stack pipe which is boxed in and tiled in most places. Looking though a small aperture in the boxing in, the pipe seems to be black and tarry on the outside and not as smooth as plastic. Is this 'pitch fibre' pipe? I've heard of this but not seen it before.
Can this be fitted with an adaptor to allow a UPVC branch from the new loo to be fitted? How would this adaptor be fitted with minmal disruption to the tiled boxing in? The pipe is fixed in concrete at the bottom and fed through the tiled roof. Ithas two loos an all the house waste water piped into it. Replacement of the whole stack would be a serious upheaval.
Any advice/weblinks etc gratefully received.
TIA
Bob