Stench pipe/soil pipe.

[scooby1]

I would appreciate a view on the effectiveness of stench pipes that don't go on to exit through the roof. I'm not sure why the builders of our new house have done this to our en-suite. We are out in the country and the appearance wouldn't have mattered. In the attached image the waste pipe can be seen coming out of the en-suite and the vertical stack finishes just before the roof. The pipe does have a cap on the top but not the white thing that can be seen, that was a polystyrene cap that just came with the black plastic cap.

What is the principle of how this works ? Does it allow air in but prevents smells from getting out ? Considering the close proximity of the roof I would have thought it would have been easier to just put it through that. I should add that this is a bedroom and the pipe is all boxed in and the floor has yet to be screeded for the underfloor heating.

Thanks for any replies.

 

[masona]

Called Air Admittance Valve

http://www.diydata.com/plumbing/air_admittance_valve/air_admittance_valve.php

 

[doitall]

It's fine for a stub stack, just make sure the boxing in has ventilation.

 

[scooby1]

Thanks guys, that is encouraging. So how do they work ? Is it essentially a one-way valve that lets air in but prevents the smells from getting out ?

 

[Symptoms]

Scoob - yep , it's a one-way valve.

Why did the builder use it? A lot cheaper than through the roof, complete with storm collar and flashing arrangements. Maybe it wasn't specified on the plans or maybe it was (planning restrictions to front elevation roofs or similar).

 

[scooby1]

Thanks again. It was never specified on the plans and it is on a roof that can't be seen from the highway. But I guess it also means that there isn't the hole in the roof that would be associated with an external pipe and the potential problems associated with that.