WC in Ensuite

[Suzanna]

Hi, advice please! We want to install an ensuite in an existing bedroom. We've have obtained 4 estimates, 3 of the four plumbers said it's not possible to install a proper toilet as the soil stack is too far away; they suggested a Saniflow (which we want to avoid if poss). The fourth plumber has suggested running a soil pipe through the interior wall behind the WC and under the adjoining bedroom's floor and then through the outside wall to join the existing soil stack. The soil pipe would run for approx 12 feet under the floorboards. Does this sound safe? Is it OK to have a soil pipe run under a bedroom floor - is there a danger it could smell, leak etc? Would we have to get permission to do this from the council?
Many thanks!

 

[Rich_Mortimer]

Hi Suzzana,

In regards to length, if the soil pipe is 100mm, it can be upto 6m long if you really want! the problem with it running under the floor is space. you need the correct fall to the pipe (Technically 18mm per meter) and the space under your floorboards probably wont allow for that. Not to mention the direction of your joists as he will have to go in the same direction rather than through them! I regard to the macerator, it will run upto 50m in a pipe s small as 19mm. This can run through joists if need be. They can be boxed in (Hidden) as long as they're accessible. Which means they can go behind plasterboard/tiles. Having a hidden trap drop for servicing is advisable. The idea of them is quite gross but they're quite good! Hope that helps!

Cheers

 

[Rich_Mortimer]

P.S. If its fitted correctly it wont leak/smell either!

 

[hi-spec plumbing heating]

soil pipe idea is never gonna happen.

 

[Suzanna]

Rich, thanks for your helpful reply. The plumber said the joists run the right way to make it possible to put the pipe under the floorboards. I asked if it would be 'slanted' enough for the waste to be able to drain away and he said yes (although not sure how he can be certain without taking up the floorboards).
Hi-Spec, thanks for replying - why do you think it can't happen?
Has anyone heard of a soil pipe being placed under floorboards successfully?
Thanks.

 

[Rich_Mortimer]

I can't say i have to be honest. If you had 200mm joists it would just about work but at a push and I cant imagine they're that tall!

Sorry!!

 

[hi-spec plumbing heating]

how much gap have you between under your floorboard to ceiling below ?

 

[Suzanna]

Hello, Hi-Spec. I am not able to take the floorboards up at present but I slid a ruler between the gaps in various places and it seems there is a 220mm gap (8.5 inches).

 

[hi-spec plumbing heating]

you maybe very lucky to just get it in, as stated if you have 200mm or more you'll just do it.
but don't drop less than 18mm/m or you'll will get blockages.

 

[Suzanna]

Thank you Rich and Hi-Spec for your replies (apologies for asking so many questions but I do not know anything at all about plumbing!) So ... with 220mm space, do you think there will be enough 'fall' and can you envisage any other problems or do you think it could just work? Also, do you know whether the council need to be informed?

 

[Rich_Mortimer]

As long as the design meets the current requirements you won't need to. The plumber will know these things. Soil can be installed both inside and outside. Really as long as he gets the best possible fall you'll be ok. He'll pipe the hand basin waste into the same soil pipe so that'll help with any "Blockages" if you like!!
The sum of it all is that as they say... it might just work! Good luck with the job.

Cheers.

 

[Suzanna]

Thank you Rich for your time, Hi-Spec also. Not the ideal way to do things I know, but feel it's a slightly better option than using a macerator so fingers crossed and we'll give it a go!

 

[ChrisR]

Dunno where 18mm/metre comes from, the Building Regs say between 9 and 90 mm/metre, and the time-honoured McGuire's rule says 1 in 40.

In other words, there's no problem with the slope, as long as it's put in carefully. The pipe mustn't sag in the middle! The only element of naughtiness in this is that the joists were probably endowed with cross-braces "X" when installed, which get in the way. Plumbers since the year dot have just bashed them out - replacing them with horizontals, "=" fashion, is better.
I'd try to use a 4m length, so there would be no joins under the floor. Depends if you have 4m clearance outside to slide it in...

Always provide a cap somewhere for rodding something like that - outside would be OK.

 

[Far North]

Hi
I'm currently doing the same thing. What did your plumber say about a soil vent pipe? My en-suite is 4m away from the main soil stack where the soil vent is. My question is will this lead to unpleasent smells coming up through the plug holes in the sink and shower in the en suite?

Many thanks
James

 

[Suzanna]

Chris, thank you so much for your helpful advice which I will flag up with the plumbers.
Far North, funny you should ask about the vent on the soil pipe because I have been wondering about that myself. My plumber did not mention the vent but I understand that building that its a requirement of the building regulations? I am going to ask him over the next few days and will post his reply. I too would not want any funny smells wafting from the pipe!