The way our extension was built (around 25 years ago) the external downpipe from the gutter was cut above the new roof and re routed. The pipe that went down the external wall which was now the inside of the extension was removed from floor level, literally. I recently lifted a laminate floor to find what looks like the jagged top of an old pipe just below the level of the floorboards. Since then we have been getting a really eggy smell when the shower is on or the hot tap has been running for a while.
I presume the gutter pipe runs into the soil pipe?
The pipe has been filled with a foam type thing (would expanding foam have been out 25 years ago?)
What is the best way I can seal it to prevent the smell coming out? Would loads of expanding foam do the trick? There just seems to be a thin layer of foam type stuff in it just now.
Cheers.