Please help - Installing soil pipe over flat roof

[Riley]

It will have to vent higher than the highest outlet

 

[Pickwickpick]

Sorry, that'll be my ignorance here, but can the ventilation not sit as it does now but with a T joint below it to connect up to the new soil coming in?

No it won't work, you need either a vent outside that goes 300mm above the eves or you'd need an air admittance valve (AAV) in the new bathroom. AAV are not a reliable and I don't like them and personally would not fit them and would want the soil stack done 'properly'.

 

[ShaunCorbs]

Sorry, that'll be my ignorance here, but can the ventilation not sit as it does now but with a T joint below it to connect up to the new soil coming in?

No as poo would come out of the vent

 

[ShaunCorbs]

No it won't work, you need either a vent outside that goes 300mm above the eves or you'd need an air admittance valve (AAV) in the new bathroom. AAV are not a reliable and I don't like them and personally would not fit them and would want the soil stack done 'properly'.

Too close to the window for an aav I would say

 

[Pickwickpick]

Too close to the window for an aav I would say

Even if its to the left of the window? Thought the 3m rule didn't apply to AAV?

 

[ShaunCorbs]

Even if its to the left of the window? Thought the 3m rule didn't apply to AAV?

Think it's reduced to 1m or 0.5m

 

[Pickwickpick]

Think it's reduced to 1m or 0.5m

Just been checking the Durgo & Floplast AAV technical brochure and I can't find any mention of a minimum distance to windows. The only reference in there about installation within a habitable space (i.e. not in the loft) is about sound nuisance and that adequate sound insulation should be used.

Having a look at the pics again, looks like it should be possible to run the stack up into the loft space above the bathroom pretty easily and then install an AAV in there which would make it a moot point and would be tidier.

 

[Bewcs]

So with an AAV the options are buy an external one and run the soil stack up the outside wall left of the window, or extend the soil stack up into the loft indoors and box it in within the room?

 

[ShaunCorbs]

Run it external up the side and vent it past the gutter

 

[NickH]

This is so ridiculous. Why on earth would anyone try to run a soil pipe across that roof with all the associated problems of fixing it and getting a fall, into that existing soil vent, with all the associated problems of removing the vent and causing other problems with the waste pipe work in that bathroom and then mess around with a Durga in or out of the loft.
For goodness sake just do it properly, dig the gully up, replace it with a soil stack, branch off for the new bathroom, take a vent pipe up and around the guttering and then reconnect the existing kitchen wastes into the stack with boss's.
It's so easy to do I can't understand why you would attempt to do anything else.
That's just my opinion of course.

 

[Bewcs]

Thanks Nick, appreciate your input.
I've had someone else finally come and take a look today, they've suggested we connect to the existing soil by running through the ceiling of the existing bathroom and boxing off which also seems feasible. Will mean a little bit of new pipe going into the flat roof but much less visible.
Will see how the quote comes back!