Soil pipe venting

[marshman]

Are you allowed to use an air admittance valve outside on the soil pipe instead of taking the vent pipe up and over the gutter,
what I'd like to do is fit one on the equal T where it enters the house at first floor height.

 

[denso13]

No, they shouldn't be outside, to prevent freezing.

 

[TicklyT]

....and they are air admittance valves - they won't allow air out if there is positive pressure in the soil stack.

 

[Richard C]

You can actually get air admittance valves suitable for external use
http://www.floplast.co.uk/uploads/Instruction leaflet for External AAV.pdf

but you can only fit one if the foul drain system has another stack with an open vent to allow for positive ventilation.

 

[marshman]

Thank you all for your time.