Venting soil stacks

[adwt2004]

hello guys

I have two bathrooms in my house. They are separately connected to the public sewer with their own stacks.

The main bathroom uses a stack that vents to outside.

The second one is capped off just above the branch.

Is it acceptable to install an external air admittance valve on this one rather than extending the pipe above roof level and venting?

Is that allowed in building regs? The regs doc doesn’t seem to say unless I’ve missed it.

Thanks

 

[Hugh Jaleak]

Regs say the highest point of the drain should be vented to atmosphere, but generally, if you've at least one open vent stack on the property, you'll be ok to use an AAV elsewhere. Its usually when folk start capping vents with an AAV the problems start.

 

[adwt2004]

Thanks. The original bathroom soil stack is vented and the pipe goes straight to the manhole. The second bathroom joins the sewer line via a clay y piece installed by Wessex Water. I will fit the External AAV on this part then.

 

[Hugh Jaleak]

You have rodding/jetting access to this run from the second bathroom I presume?

 

[adwt2004]

The AAV is a push fit and about 2.5m from the 90 bend which leads to the sewer pipe (all outside). You could rod from there right? I looked at swapping the bend that's been there for one with a rod eye but it would be in the ground. Is there a better way?

I did also think about changing it to a T at the bottom so I can then add a rodding eye like this one to it

https://www.screwfix.com/p/floplast...gclsrc=aw.ds&dclid=CMvtx6K7-NkCFegR0wodDBgA7w

Pipe Design

• adwt2004
• 19 Mar 2018

 

[Hugh Jaleak]

The stack is external? Fit a rodding eye at ground level, probably be easiest. https://www.screwfix.com/p/floplast-sp581-single-socket-access-pipe-black-110mm/82593