Toilet pipe under a pergola, do i have to vent?

[xaerocool49]

Hi there,

I have a new soil stack going into the sewers, the ground workmen did the ground works and capped the pipe for when the new ensuite was ready which i'm doing myself on the first floor.

I have a pergola on the back of the house. The new toilet soil pipe comes out underneath the pergola roof, then it would simply go down the backwall into the new capped soil pipe into the sewer. Do i have to cut a hole in the pergola and go up so the top of the 2 story roof level to vent the soil stack? The new soil stack is immediately next to the back door, what if i was to vent the pipe outside underneath the pergola roof? Is there a risk of smells and such?

Thank you,

J.

 

[Wayners]

Fit a air admittance valve inside maybe?
Always better to have open soil pipe above roof line.

How to use an air admittance valve - Drainage Superstore Help & Advice

What is an air admittance valve? Air admittance valves, also known as AAVs or durgo valves, are valves that help to re-balance the pressure within a soil

www.drainagesuperstore.co.uk

Oh valve don't let air out. Only in.
Won't have smell under pergola

 

[Hugh Jaleak]

If another Vent Stack already on property, then no, cap with an AAV. If not then I'd recommend you vent it to save issues down the line. If venting, you'll need to go up high enough to prevent odours entering the property through windows/airbricks and/or not causing a nuisance.

 

[xaerocool49]

Hi @Hugh Jaleak, @Wayners

Many thanks for your answers, yes there is a second vent stack. It's a 1930's semi with a two storey side extension so the first vent runs up through the middle of the house, up through the loft and out of the roof tiles.

This is a new stack at the very back of the house so just drops into the same manhole/sewer the one in the middle of the house runs into.

You mentioned the air admittance valve inside, the toilet is against the back wall, so there isn't really an 'inside' the pan will have the soil pipe go straight back horizontally through the wall and with an elbow go down vertically into the soil pipe. So I think the only place i can place the AAV on the vertical part of the soil pipe going from the toilet to the hole in ground pipe...would that be ok then?

Thank you

J.

 

[Hugh Jaleak]

Fit the AAV externally, soil pipe from WC through wall, into a junction. Go up from the junction as far as you can, fit AAV on the top. Just allow room to remove it if you ever need to repair or replace going forward.