Soil stack ventilation - air admittance valve to meet part N?

[Conor]

Architect has specified one stack with an AAV, and the other (main one) with a vent slate at the top of the roof.

 

We can't get a vent slate that will fit between the steel channel sections in our thermohouse panels (200mm), and roofers will be slating there tomorrow so limited options!

 

I've just reread Part N and in all three paragraphs referring to ventilation (ventilation stack, discharge stack and separate vent) state that an AAV is acceptable. Is this correct?!

[Dave Jones]

yes thats correct you can use a durgo valve

[Jenni]

My BCO was happy for an AAV and a "trickle" vent through the roof - only had to be 32mm.

 

[Marvin]

Hi Conor

 

As we know an AAV let's air in and a vented soil stack let's air in and out. It may be that the Architect feels there is the possibility of air pressure building up enough  in the soil pipes to cause some of the water traps to fail expelling smells into the building. 

 

This possibility requires consideration of the pipework in the building as well as all the way down to the first vented soil stack which could be several houses away.

 

So I wouldn't just slap an AAV in without checking. It may also be a smaller pipe will do the job.... 

 

Then again a possible retrofit if you have a problem?

 

Best of luck Conor

 

Marvin

 

 

 

 

Edited July 20, 2021 by Marvin
Clarification, hopefully.

[Conor]

Thanks @Marvin. If it makes a difference, the soil pipes enter inspections chambers right outside the building, and flow along our own private pipe to the public sewer.

[Marvin]

Could be the Architect is just being cautious. Any chance of a quick call to ask the Architect Tomorrow?

 

Maybe a retrofit? Sorry I don't know how difficult that would be with your roof design.

 M.

 

 

[Marvin]

17 minutes ago, Conor said:

Thanks @Marvin. If it makes a difference, the soil pipes enter inspections chambers right outside the building, and flow along our own private pipe to the public sewer.

So no other soil pipe air venting on your property in the design. Its possible that the Architect is just being cautious. May have been a problem before on another job. During high winds here I have witnessed strong airflow out of soil stacks...

 

M

[dpmiller]

have you looked at both your neighbours for stacks? @Conor