How to connect shower waste into horizontal soil stack

12 Jun 2009
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United Kingdom
The soil stack runs horizontally along the bathroom floor and I need to connect a 40mm shower waste to it. Will it be okay (and meet building regs) if I fit a boss strap into the side of the pipe? (i.e. going into the horizontal soil pipe at 90 degrees and also horizontally)
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NO, waste pipes have to have a fall!
ALso if you want to comply with regulations, you can't use the normal shower trap, you need a 50mm seal.
Thanks Chris - 50mm seal into 40mm waste noted.

I'll make sure there's the 1 in 80 fall, but what I was tryingt o ask is can teh 40mm waste go into the side of the 110mm soil pipe (that is lying at 1 in 80 fall)?

It will look like this (but horizontally instead of vertically):
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A 1 in 80 fall is insufficient, it works out at 12.5mm per metre, recommended fall is 44mm per metre which is 1 in 22, the absolute minimum permissible is 18mm per metre which is a 1 in 55 fall but this is really quite flat and not recommended.

You can boss into the side as you suggest, but make sure it's upstream of any toilets and also consider fitting an antivac trap to prevent a flushing loo pulling the trap water out
On a single stack soil vent pipe system, all waste pipes must go into the vertical SVP, look at the basic design of these systems on any plastic system manufacturers installation details!!

It amazes me how people with limited knowledge of basic Plumbing systems think they can give advice on here??!!

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