Info on Air Admitance valves would be a great help

[harris48]

Hello there, I am in the process of changing my soil stack and I am contemplating cutting down the height of the pipe to create more space in my bathroom (It is an internal stack). I was thinking of fitting an Air Admittance valve and would like to know what the building regulations are in terms of the minimum position for this to be installed above the last connection to the soil pipe (which is the WC). Can anyone tell me what height I can cut the soli pipe and replace with an Air Amittance valve.

Any info would be greatly received.

Cheers

 

[chrishutt]

Google on Building Regulations and look for Communities and local government where you will find document H1 which deals with these matters.

 

[ChrisR]

Note that you will be losing the letting-air-out property of an open stack.