Soil stack replacement Q

[Jethro]

Hi guys

our bungalow ("L"-shaped) has a nuisance soil stack (stench pipe) situated in the back, in the inside corner of the "L". Currently it's made of cast iron, looks grotty,and is a pain, as the guttering is squeezed behind the angle where it goes up.

I know it's possible to replace it with a straight pipe, which enters the eaves, and vents through a chimmney in the roof (replacing a tile).

However, since the purpose of the pipe is to admit air (to prevent siphonage), is it possible to fit a new shorter pipe, with an air- admittance only valve ? I'm sure I've seen one advertised ...

thanks in advance

[Jim]

It's not only to admit air - the stack pipe also has the function of venting the sewer. Building control like to see a vent every few houses.

[Tim S]

Jethro coughed up some electrons that declared:

Having just done one, you can certainly tweak it out more - two 135 degree solvent bends to swan the pipe out can clear the gutter by quite a wide margin. Solvent weld ensures the free standing bit of 1m ish dangly pipe can be sufficiently supported by the clips below it down the wall.

You can do the vent pipe in 82mm too - black PVC looks fairly smart.

Yes - I used to have one like this.

No - you need to be able to vent positive pressure too.

Building regs say vent is >=3m from all openings *or* 900mm above the tops of those openings that are closer than 3m.

Cheers

Tim

[Lobster]

Yes that's one of the specific regs: if next door has a vented stack you're probably OK. Also you can't be the last property at the end of a row (eg cul-de-sac) so that your AAV valve is at the blind end of the drainage system.

David

[Hugo Nebula]

On Mon, 29 Jun 2009 04:51:44 -0700 (PDT), a certain chimpanzee, Jethro randomly hit a keyboard and produced:

You can't mount it externally.