Horizontal soil pipe connections (manifold?)

[Smo]

Is it possible to connect 2 WC's to a single horizontal soil pipe

I am considering turning a walk in wardrobe between our main bedroom and bathroom into an en-suite. The wc in the main bathroom is against the North wall, and drains to the soil stack on the East of the house. If we go with the en-suite idea, the second wc will also be on the North wall, to the West of the existing WC, so will need to drain past it. It seems logical to me that they could share a common horizontal drain into the soil stack, but this would mean the drain from the main WC dropping vertically into the horizontal pipe as it passes. Would this be a problem?

If this is possible, would it need something at the top end to prevent siphoning? I can see this might affect whether we choose to plan for a load of boxing out and have a concealed cistern, or have minimal boxing out and go for close coupled.

Reading on the internet, the only reference I can seem to find is to manifold connections on the marley website, but not sure this is the same thing.

I know I'll need a plumber and building regs for this, but for the moment, just trying to establish whether it is realistic to try and make this room an en-suite, or just have it as a walk in wardrobe.

 

[Bamba71]

As long as you place a vent stack somewhere between the 2 soil pipes that exit your house (or directly to 1 of the pipes that exits your house) via a 4" tee it will work fine, a vent stack is just a length of soil pipe that rises vertically to just above the facia boards on your house with a vent cap on it at the top, if you look on other houses you will clearly see a vent stack rising up in this way & of course the pipe will need to slope towards the main drain.

 

[Nige F]

You are right about the Marley . And as Bamba says . If you set it out like
1_______2______3_I ...............1 is the vent 2 is a WC 3 is a WC I is the stack to vent and down to the drain .... I`m computer illiterate

 

[lifesagasman]

i see why the OP has a concern about the mid 4" dropping vertically into the horizontal. would it not be best led in at 45 deg?
i'm not a soil pipe technician....

 

[Nige F]

Good point - no it`s not a problem because there is another WC upstream . and any "sleepers" will be shifted when the upstream WC flushes, so 45 is not necessary . Would be if it was pipework that flows full of water - but drains don`t, and there are calcs. etc. that allow for this . I would possibly put an access bend on position 1 in case it`s needed once in a blue moon

 

[Smo]

That's great news.

Can the upstream stack be internal rather than penetrating the the roof.

I have seen mention of an 'air admittance valve', but not sure if i am getting the right end of the stick?

 

[lifesagasman]

you need a WRASman to say if AAVs are ok as air breaks.

anyone out there?