Wetroom - tapping into soil stack low down

21 Aug 2021
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United Kingdom
Hi all, will be getting a plumber to do the work but have had differing opinions and want to crack on with the other work required which means I need to raise the floor to the correct level. I live in a second floor flat, there's one flat above me. I'm adding a small en-suite wetroom but the soil stack connection is pretty awkward. Toilet will be going just to the right of the stack and shower just to the left, with sink pretty much right in front of it.

What's the best way to make the waste connection as low as possible? The soil stack goes into the concrete floor. I was thinking it would be best to cut it as low as possible, then use something like this, but it says this should only be used on ground floor because it reduces internal diameter of the pipe?

Also the gas meter pipe is right in the way and will need to be rerouted! Here are some pics:

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Basically I want that 3 way boss you can see on the soil stack to be moved as low to the concrete floor as possible (so I can keep the shower/floor as low as possible), and have a toilet connection on the right side instead of 50mm waste. Hoping that makes sense!
You are seriously going to struggle to do anything with that I think. Main issue is, you've only got the socket available immediately above the floor and the Fire Collar, so nothing to attack to externally.

The only thing I can suggest that might work, is a McAlpine DC-1 with Boss, cut the soil pipe flush with floor, and insert the McAlpine Fitting which will give you the low connection I think you need. Just hope it doesn't leak! https://www.toolstation.com/mcalpin...ZSB_XHFINuAPaBc37URoCYfwQAvD_BwE&gclsrc=aw.ds
Ah yes I saw this too, thank you!

It says: Should only be fitted on ground floor due to a reduction in the internal outlet diameter of the boss pipe connector

Do you think that's an issue? The "just hope it doesn't leak" isn't filling me with confidence hahah. I really appreciate the response though!
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They aren't my first choice of fittings as the reduction in bore is never ideal, but if their use cannot be avoided then needs must. Any joint has the potential to leak, but given you have no control over discharges from above, and have someone below, then leaks are best avoided!

Other option could be to look at a pump, the 'Whale Gulper' is one such device.

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