Help and Advice - Going from 2 SVP’s to 1

[James7491]

Hi all. First time poster. Currently renovating our 4 bed house, built in 1988. We’ve just finalised our architect plans for our extension and downstairs reconfiguration. As part of our plan, we need to get rid of one of our SVP’s, the one that currently serves the main bathroom. The plan is to then have both the main bathroom and en-suite, use the existing SVP in the en-suite. Although our architect says it will be fine, I have serious concerns that this just won’t be possible, due to the distances involved and due to everything coming from the same side. Please can I seek the advice of you wonderful professionals so I can decide a way forward.

I’ve attached the architect plans for proposed ground floor and 1st floor. Screenshot of proposed bathroom layouts has existing SVP’s marked in red, including showing which one is going. I’ve also attached a photo of the en-suite now that it’s been ripped out so you can see the SVP that’s staying. 

Thanks.

[Nickfromwales]

You’ll be fine. 
 

Done plenty of bathrooms back to back like this on one stack and sometimes no SVP at all, just an AAV (air admittance valve) to ensure functionality. 
 

Green light from me, and I’ve been joining pipes together for 35 years.   

[James7491]

8 hours ago, Nickfromwales said:

You’ll be fine. 
 

Done plenty of bathrooms back to back like this on one stack and sometimes no SVP at all, just an AAV (air admittance valve) to ensure functionality. 
 

Green light from me, and I’ve been joining pipes together for 35 years.   

Hi Nick, thanks for your reassurance. How exactly will it work? Will I extend the horizontal soil pipe through the wall into the other bathroom, and then have the second toilet connect into it? Are there issues when connecting 2 toilets to the same horizontal pipe?  

[Kelvin]

I fitted our SVP in the detached garage that’s 6m from the house. There’s an AAV off the upstairs bathroom in the roof void. No penetrations through our roof. Works perfectly. 

[Gone West]

We had back to back bathroom and ensuite which both connected to a single stack with an AAV. It was a snug fit and the BCO was interested but happy it was all ok.

 

[Nickfromwales]

3 hours ago, James7491 said:

Hi Nick, thanks for your reassurance. How exactly will it work? Will I extend the horizontal soil pipe through the wall into the other bathroom, and then have the second toilet connect into it? Are there issues when connecting 2 toilets to the same horizontal pipe?  

Yes, they both can be on one run, up to 4 WC’s iirc. You can get a Y branch and a T branch, and this needs thought and planning. 
 

Ideally you’d have a Y branch with a 135° male to female bend in it, which then picks up WC 2, so the flushed water is already heading in the direction of flow. 
 

If you’re too tight for space to do this then you can use a T branch, but it should be lower than the outlet which is difficult to do with a standard, close-coupled WC. 

 

If you’re using framed units (like a geberit) then it’s really easy as the pipe centre for the WC outlet is much higher than the standard 7” centre of a regular UK WC.

 

Best to get some fittings and see what will won’t work by doing some dry mock-ups.

 

Are you using framed (floating) wall hung or regular WC’s? Using one of these at WC 2 would make life a lot easier for you. 

[James7491]

2 hours ago, Nickfromwales said:

Yes, they both can be on one run, up to 4 WC’s iirc. You can get a Y branch and a T branch, and this needs thought and planning. 
 

Ideally you’d have a Y branch with a 135° male to female bend in it, which then picks up WC 2, so the flushed water is already heading in the direction of flow. 
 

If you’re too tight for space to do this then you can use a T branch, but it should be lower than the outlet which is difficult to do with a standard, close-coupled WC. 

 

If you’re using framed units (like a geberit) then it’s really easy as the pipe centre for the WC outlet is much higher than the standard 7” centre of a regular UK WC.

 

Best to get some fittings and see what will won’t work by doing some dry mock-ups.

 

Are you using framed (floating) wall hung or regular WC’s? Using one of these at WC 2 would make life a lot easier for you. 

Hi Nick. Thanks again. I think I understand you. I have thrown a rough sketch together to ensure I understand. 90° turn in main bathroom to start the horizontal pipe. Horizontal pipe remains straight, through the wall, to the SVP, with the en-suite toilet connecting via a Y Branch connector? Is that right? Obviously maintaining a fall on the horizontal pipe. 

 

Regarding toilet type, attached is what we’re going with for the en-suite. Main bathroom is undecided, but likely to be a freestanding toilet. 

[Nickfromwales]

Ah, cool. Picture speaks a thousand words, and all that jazz.

 

The fitting in the corner will need to be one of these 

 

https://ebay.us/m/ICnVBo

 

You don’t have 2 WCs in one 110mm line so my previous about Y branch can go away. All good with 90° bends (bent pan connectors) and straight runs. 
 

For the double corner branch, just order a cleaning / rodding eye (access cap) to push into the top outlet to close it off. 

[James7491]

@Nickfromwales 

Sorry Nick, you’ve lost me now. You’re now saying both toilets can’t share the same horizontal pipe? If so, how will I have space to run 2 individual 110mm pipes to the SVP, especially as they would be connecting at the same side? 

[James7491]

17 hours ago, Nickfromwales said:

Ah, cool. Picture speaks a thousand words, and all that jazz.

 

The fitting in the corner will need to be one of these 

 

https://ebay.us/m/ICnVBo

 

You don’t have 2 WCs in one 110mm line so my previous about Y branch can go away. All good with 90° bends (bent pan connectors) and straight runs. 
 

For the double corner branch, just order a cleaning / rodding eye (access cap) to push into the top outlet to close it off. 

Sorry Nick, you've lost me now. You're now saying both toilets can't share the same horizontal pipe? If so, how will have space to run 2 individual 110mm pipes to the SVP, especially as they would be connecting at the same side?

[Nickfromwales]

19 hours ago, James7491 said:

@Nickfromwales 

Sorry Nick, you’ve lost me now. You’re now saying both toilets can’t share the same horizontal pipe? If so, how will I have space to run 2 individual 110mm pipes to the SVP, especially as they would be connecting at the same side? 

I’m saying you don’t have one run with a WC on the end and another further down the same pipe, you have 2 pipes, one in each room. 
 

Therefore you can ignore my corner branch as I mistakenly thought you dropped in the corner that side. 
 

Can you dril through the wall and connect the WC closest to the SVP into the horizontal run of the other WC?