DIY Doctor

Two toilets running in to one soil branch?

Postby MJW16 » Tue Jun 16, 2020 12:40 pm

Hi all,

We are in the middle of a project to turn our chalet bungalow in to a house. As part of that, there will be an en-suite and a family bathroom at the back of the house, the toilets in these need to discharge to the existing vertical soil stack position.

If the stack came up between the two toilets I'd be happy and not writing this post - a toilet in from either side, not a problem.

Because the arrangement is such that both toilets are on the same side of the stack, I'm concerned about them sharing the same horizontal branch in case of siphon/suction action on one toilet when the other is flushed.

I've attached a crude drawing of the layout, viewed from the outside. The soil stack is just a stump at the moment for me to extend up to the appropriate height with a vent cowl as and when. Fixed points are red, the soil pipe arrangement I need to install but have concerns about is in blue.

Any thoughts and advice on this would be very welcome. Perhaps an alternative pipework arrangement, or a strategic durgo/aav to stop any siphon action?

Thanks in advance
Soil layout.jpg
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Simply Build It

Postby stoneyboy » Tue Jun 16, 2020 11:00 pm

Hi mjw16
Fit an Ava on both toilets and you should be ok.
Regards S.
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