Shower waste pipe into caste iron soil pipe?

6 Jan 2008
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United Kingdom
I'm just after some advice on installing a shower into my cloakroom. The cloakroom has a toilet and a sink in it and I wouldn't be doing the plumbing myself.

I'm just having trouble understanding how the waste water from the shower is drained. Given that the shower drain is virtually at ground level, the toilet soil pipe branch is virtually at ground level and that you can't add a branch less than 150mm below the toilet branch, how are shower waste pipes fitted in a room where there was previously no shower?

I'm really confused!
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Having an offset opposed connection to the soil stack?

Or, depending on the distance to the floor, couldn't you just discharge to a drain?

How is your basin waste connected?
Thanks for the reply.

The cloakroom is on the first floor above the kitchen. There is a service channel running between the two through which runs the soil pipe and various hot and cold water pipes. The toilet branch of the soil pipe has the bottom collar about 3 inches below the level of the floorboards and the shower tray will be on a 4inch? riser on the floor.

The basin waste water pipe drains into the soil pipe above the toilet branch, say about 18 inches off the floor.

I can't find any more info about an offset opposed connection.

To be clear, I'm going to get a plumber in to do the job, but I've been very badly ripped off by tradesmen this year so want to learn as much as I can before getting someone in.

Thanks again.
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Difficult to imagine your layout but if access is possible downsatairs in the kitchen, the shower waste can be dropped drown and connected lower down. But, it sounds like there is enough 'fall' anyway to connect just below the floorboards - perhaps with some boxing in.
I hope these help. All of these old fittings and boxing will be replaced and the shower will be fitted to the left of the sink.

Thanks for the link, Teatime, I'll have a read of that now.

I think Squeaky's suggestion may well be the way to go. There's no problem creating a service panel in the kitchen below, just below the ceiling, which will give greater access to fit the branch to the soil pipe below the toilet connector collar.

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