Where is the top of my soil stack?

[AdamW]

I live in a first floor maisonette with my bathroom above the bathroom of the guy downstairs. It seems we share a soil stack as it appears to be boxed in in the corner of my bathroom. Now, the boxing runs all the way to the ceiling but I can't find the top of the stack in my loft.

My question is: does the soil stack go up above the highest entry point on it? In other words, is it likely that the soil stack is just a foot or so higher than the point where all my waste pipes join it, or will it be 7 foot higher? I don't want to start ripping out the boxwork and find a big smelly pipe there!

 

[breezer]

i believe it should go out through the roof, but on the other hand it may have a "special valve" it allows air to be sucked in when water is flushed down the pipe, this saves going through the roof, perhaps you have one of these?

 

[AdamW]

Definitely doesn't go through the roof so I think you're right. Looks like the boxing in is staying then!