Soil stack?

[Stinkoman]

My house is upside down - kitchen/lounge upstairs, bedrooms/bathrooms downstairs. Roof is still on top of the house :)

In the en suite, I've got what I sugess is a soil stack pipe... except that it's capped at around 1.5 metres in height. It requires its own plastboard housing so it can be hidden away.

The toilet goes into it at the bottom, as does the sink and the shower drain.

Anybody know the reasoning behidn it? I guess it's so that if there's a blockage further down the drain system, there's space to backup? But, equally, woudn't that backup head up the sink/shower drains and start to overflow? What can I do about this? Is there a non-return value system?

[Set Square]

What do you mean by *capped*? Chances are that it has a Drago-type air admittance valve at the top. This lets air *in* to prevent a vacuum from developing in the stack - but lets nothing out.

I presume you have another stack which is much higher, and vented at the top?

[Hugo Nebula]

On Sat, 9 Apr 2005 18:43:18 +0000 (UTC), a particular chimpanzee named "Stinkoman" randomly hit the keyboard and produced:

If I understand you correctly, this is on the ground floor. If so it could be a 'stub stack', which is a short unventilated stack connecting to a vented drain or sewer a short distance away. It doesn't need a vent, as the chances of siphonage are very small. There's no reason for it to be a 'stack' apart from it's easier to connect the smaller branches into its side that way.

It could also have a "Durgo" or air-admittance valve on the top if this stack is a long distance from a main drain.

Any blockage should be capable of being cleared by an access or inspection chamber on the branch drain, or preferably at its junction with the main drain.

[Stinkoman]

Sorry, yes, you're right. It's not capped - there's a one-way air valve at the top.

Now I think about it, there is a soil stack outside which runs to the top of the building, despite nothing actually going into it at that level.

This used to have an even higher (and rather silly looking) pipe into the top of it, going beyond the height of the roof. I know this from a photo of the building when it was first renovated. This high pipe is no longer there - I presume it got blown down at some point.

[Dave Plowman (News)]

That's the vent for the drains?

I had the same, but had it removed when doing an attic conversion. They ran it along the side of the house well clear of any windows and added some sort of valve.