AAV or SVP?

[peteypops]

I've requested from our architect to have our drainage arranged with an AAV for each toilet. These will be contained in walls or boxing. This would look like this -

 

My architect insists that the long run needs an open SVP running into the roof space as follows -

 

Can anyone offer any insight on this as I'm pretty sure the AAV's are adequate.

 

Cheers

 

Pete

[G and J]

I’m guessing the AAVs are more than adequate in letting air in to prevent a vacuum be created behind a flush.  
 

But, sewers can back up and when they do air needs to be released from the sewer pipes or potties can start ‘burping’ which would not be nice.  
 

Even without a blockage I would imagine (though don’t know from direct experience) that localised raised pressure can occur in sewers. Maybe cup final half time all your neighbours go to the loo at once and all flush at the same time?

 

Whatever the cause you want back pressure to waft harmlessly away rather than pushing stinky smells back into your lovely new home.  So I’m with your architect on this one. 

[Alan Ambrose]

Guys, I haven’t had my breakfast yet.

[Kelvin]

You might not need one if your neighbours have them on the same sewer line. I didn’t want one coming up through the roof of the house either so we extended the drainage into the detached garage and the SVP comes up through the garage roof. We also fitted the garage with a shower and a dog bath. 

[saveasteading]

Venting into the attic doesn't seem nice unless it is draughty. Best to avoid roof penetrations when possible too.

Can it come out under the eaves?

OR can that upstream manhole be ventilated?

[G and J]

4 minutes ago, saveasteading said:

Venting into the attic doesn't seem nice unless it is draughty. Best to avoid roof penetrations when possible too.

Can it come out under the eaves?

OR can that upstream manhole be ventilated?

The soil stack can terminate at a ridge vent.  Yes it’s a penetration of the airtight layer somewhere but at least it’s not unsightly.

[Bramco]

To avoid a penetration in the roof, we ran a pipe parallel to a downpipe outside the house. This was connected to the last manhole before the long run to the main sewer. The top of the pipe was fitted with a slatted vent and sits up against the gutter.  It was a suggestion from BC when we asked how we could avoid penetrating the roof.

 

Simon

[peteypops]

Thanks all. So I guess a vital piece of context is that this is hooking up to a water treatment plant, just out of frame from the picture I posted. So no sewer issues as such, but, back pressure is still possible I guess. I had similar misgivings about venting into the loft space, (outside the thermal envelope) and I like the the idea of a separate external vent pipe so as not to have to penetrate the roof, but getting one up to the ridge line is tricky