Connecting new toilet soil pipe to existing one

RScorpio · 25 Nov 2019

Hi,

I live in a victorian terraced and have a downstairs bathroom in the extended part of the house with the soil stack running into the ground.

I want to get an ensuite built on the upper floor. There are no soil stacks visible anywhere else. One thought to avoid digging up the ground outside for a new soil pipe connection was to somehow connect the new toilet soil pipe to the existing one.

I have attached a photo of the current soil pipe running into the ground.

I was considering using either a corner branch pipe connector or a connector like this, where one end will run into the ground.

https://www.jtmplumbing.co.uk/pipe-...tings-c741/jtm-double-socket-branch-92-p23355

The toilet will need to move forward so that space can be created for the top opening to be used for the new toilet pipe waste connection.

Is this doable? Any suggestions welcome. Thanks

Bonni · 25 Nov 2019

That fitting won't work and a fitting doesn't exist to do what you want. You theoretically need a 90 degree elbow with a vertical outlet on the corner pointing down, such a fitting doesn't exist. You will need to dig up outside to connect in. Then the soil stack to the en-suite will either go on the outside or if it was internal, you need to take your downstairs loo tiles up. The soil stack position may be determined by the layout of your new en-suite.

CBW · 25 Nov 2019

I would say it’s doable, heights and number of bends etc permitting: McAlpine DC1-Bl and a branch should assist, but it then depends on where you want to go from there.

Hugh Jaleak · 25 Nov 2019

It's unlikely to be do-able, (legally) anyway. Bends are not permitted in the wet section of a stack unless completely unavoidable, and given your description, I have a gut feeling it wont be a straight run from the existing WC position to the proposed en suite WC, which makes me suspect the idea is a non starter. Without Building Regs you may struggle if you want to sell the property at a later date, and applying them retrospectively would require the job to be done properly.

It's likely the only method Building Control will accept is to dig down and find the existing sewer, make a connection there, and run a new drain back to the exterior wall of the building, before turning upwards with a rest bend, then coming up with the stack to suit proposed new WC position. Done plenty like that, including my own. If you need any more advice, just ask.

CBW · 25 Nov 2019

@Hugh Jaleak i couldn't see the mention of no bends in a wet part of stack in document H, is it somewhere else?

RScorpio · 25 Nov 2019

Hugh Jaleak said:
It's likely the only method Building Control will accept is to dig down and find the existing sewer, make a connection there, and run a new drain back to the exterior wall of the building, before turning upwards with a rest bend, then coming up with the stack to suit proposed new WC position. Done plenty like that, including my own. If you need any more advice, just ask.

Thanks very much, will definitely be notifying building control to avoid future complications, so seems like what I had thought about may not work. New soil stack it is in which case.

Newboy · 25 Nov 2019

The Novice said:
couldn't see the mention of no bends in a wet part of stack in document H,

1.27

Hugh Jaleak · 25 Nov 2019

The Novice said:
@Hugh Jaleak i couldn't see the mention of no bends in a wet part of stack in document H, is it somewhere else?

Section 1:27 "Offsets in the 'wet' portion of a discharge stack should be avoided." It goes on to talk about what happens if they cannot be avoided, and in taller buildings.

Bends are never a good idea, noise is one issue, a falling discharge is quite loud when it hits the base of the bend, possibility of blockages is another reason. There are times when use of bends is unavoidable, e.g. an external stack using 2x 45° bends to 'dog leg' over corbelled brickwork, but if use of bends can be avoided then it is preferable.

One of the reasons a long radius bend is used at the foot of a stack is to allow a smooth passage from vertical to horizontal, and avoid compression of the air in the system. Likewise why connections are not permitted into the stack within 450mm of the invert of the drain.

RScorpio · 30 Nov 2019

Hugh Jaleak said:
It's likely the only method Building Control will accept is to dig down and find the existing sewer, make a connection there, and run a new drain back to the exterior wall of the building, before turning upwards with a rest bend, then coming up with the stack to suit proposed new WC position. Done plenty like that, including my own. If you need any more advice, just ask.

Thanks, I was going to go for a new soil stack connection but then realised I have a few more issues around this with building control and public sewerage maybe to first sort out.

I have created a new thread in the building regs section. Appreciate further advice.

https://www.diynot.com/diy/threads/new-foul-pipe-connection-issues-for-ensuite.534364/

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Connecting new toilet soil pipe to existing one

RScorpio

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