Extra sewer pipe to toilet bend?

[Wiredcharlie]

Visualise this if you can!
Downstairs toilet below new en-suite. Downstairs wc exits horizontally into elbow then into floor. Is there a connector available that can replace the existing elbow allowing an additional side access for connecting the upstairs wc.

Much appreciated

Tony

 

[Richard C]

You can’t do that; you will need to erect a new stack, either vented external or fitted with an AAAV but you must also have another open vented stack elsewhere on the system to allow for positive ventilation. It’s also notifyable building work requiring a Building Notice submission, as is your new en-suite.

 

[Wiredcharlie]

Thanks for your help Richard. If it was vented to outside above the en-suite would it still need a separate stack?

Tony

 

[Richard C]

You need to follow a few basic rules but it’s OK to take a new stack upwards from your existing loo to serve the new en-suite. Because of the height above the drain & the problems it would give with pressure/siphoning when you flush the upstairs loo, the top of the stack must either be vented to open air (outside) or using an AAAV above the highest flood point inside but to do that, you must have an open vent somewhere else on the system.

As I said earlier, this is notifyable work.

 

[Wiredcharlie]

Thanks, that really helpful. Back to my initial question:-
Downstairs toilet below new en-suite. Downstairs wc exits horizontally into elbow then into floor. Is there a connector available that can replace the existing elbow allowing an additional side access for connecting the upstairs wc.

Much appreciated
Tony

 

[Hugh Jaleak]

Not sure I can entirely visualise the existing situation or what you are hoping to do. Picture tells a thousand words if you could put one up?

I would want to take the 110mm pipe straight up from existing soil connection in the floor to serve the new en suite, then fit a 'T' at the appropriate height to connect the existing W.C. Bends in the wet section of a stack are best avoided, and I think if you are hoping to run the soil from the new W.C. horizontally past the outlet of the existing W.C. then you could could be asking for problems...

 

[Richard C]

I would want to take the 110mm pipe straight up from existing soil connection in the floor to serve the new en suite, then fit a 'T' at the appropriate height to connect the existing W.C.

I thought I already said that ---- but it must also be vented, as I've already explained.

Bends in the wet section of a stack are best avoided,

Not only are they best avoided, they are not permitted under BR's; you are allowed a limited offset in the wet section of the stack but there are restrictions where you can do it.

and I think if you are hoping to run the soil from the new W.C. horizontally past the outlet of the existing W.C. then you could could be asking for problems...

Maybe me but I really don’t understand that!

 

[Hugh Jaleak]

Sorry Richard, I had a mental image of what I think the OP has now, and then was hoping to achieve, I may be wrong, but was putting my thoughts into words. Having seen the arrangements employed by some in the past then anything could be possible!

I hope the OP will clarify what he is hoping to achieve with a picture, which would assist a great deal. I may have overcomplicated the existing setup in my mind, but the OP is looking at a side connection. A double corner branch may be what he is hoping for, but then there would need to be a 90deg bend at the base of the stack from upstairs, which as you've pointed out is probably not allowed.

I was unsure if the existing outlet runs horizontally as in a 'P' trap pan, with a 90deg pan connector into the floor, or uses a 90deg pan connector to go horizontally into a stub stack, offset from the pan.

 

[Wiredcharlie]

Untitled

• Wiredcharlie
• 1 Feb 2010
• 1

Unfortunately I can't upload a photo because it's my dads and is some 300 miles away. However, this sketch should clear up the uncertainties.

 

[Hugh Jaleak]

Richard may be able to clarify for definate, but i'd think no. You have a 90deg bend in the wet part of the stack, which is not allowed.

Where does the drain from the existing toilet go? If it was to go straight outside at that point is it feasible to install an external stack for the en suite and couple into the drain from the ground floor toilet outside?

 

[Richard C]

Er no; Building Regs. wont allow that, it would never get passed on inspection & your likely to get a nice back wash up the bog on the ground floor when you flush upstairs. Hugh's suggestion is practical but there are other ways; before doing any work you need to understand a bit more about what you can & cant do so I would suggest you read the Building Regulations;
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf
this is just drainage, you need to comply with others in the en-suite itself.

& this useful design guide:
http://www.hunterplastics.co.uk/download/29/Design Criteria.pdf

This work & the new en-suite will require a Building Notice submission, LABC inspection & possibly a witnessed test; there is a fee for this. Come back with specific questions if you have to.

 

[Wiredcharlie]

Sorry, the diagram shows the existing downstairs toilet. The upper frame shows the sewer pipe exiting horizontally and turning 90 degrees into the floor. The lower frame is the same downstairs toilet showing the hypothetical connection to the upstairs en-suite.

 

[Richard C]

The lower frame is the same downstairs toilet showing the hypothetical connection to the upstairs en-suite.

I did understand it; that 90 degree bend is your problem. The stack must (effectively) be vertical from top to bottom into a slow rest bend at the bottom below the ground floor toilet where it meets the drain invert - the bit under the ground.