Soil Stack for en-suite

[buzby]

Hi all,

Newbie posting, so my apologies if this has already been covered! (I have searched, but not found the complete answer to my problem).

I have a detached, two storey house, built in 1979. I am fitting an en-suite bathroom into my upstairs bedroom, consisting of toilet, sink and shower. My problem concerns fitting the three wastes to the main sewer.

The house has two toilets, one connected to an internal soil stack in the corner of house. Unfortunately this stack is too far away for me to connect to it. The other toilet is downstairs and the waste goes straight through the floorboards and, presumably, straight to the sewer. I would ideally like to create a stack from this wastepipe if possible.

The downstairs toilet is positioned in a room below the location of the en-suite, but the waste is about also about abount 12 foot horizontally along, so I intend to run the branch horizontally underneath the en-suite's floorboards, then down through the ceiling of the toilet below and into the waste connection. I would create an appropriate fall-off in-between the floor-boards so everything flows the right way, and I also intend to create a vent through the outside wall.

See diagram below for a better idea of what I would like to do.

Questions:
1) Is this workable?
2) Is it OK to connect appliances to a horizontal run, rather than vertical?
3) What minimum fall-off would I need for the 12 foot horizontal run?
4) Can I reconnect my downstairs toilet to the new stack and would there be any likely issues with doing so?

I'm hoping this is OK because my house is built on raft-style foundations and so any new external stack is likely to cost lots of building work £££!

[/img]

 

[Expertboy]

I would run a complete soil stack externally (vented to the roof) and connect this to the existing drain.

You can then connect all your appliances into this soil stack including your downstairs toilet.

 

[peca27]

Yep it's workable + you can connect to a horizontal run- as long as you meet the min. gradients as spec. in Part H of the Bldg Regs.......eg, for a 100mm pipe size you would need min. gradient of 1:40.

See http://www.odpm.gov.uk/index.asp?id=1130478

It should be ok to reconnect your old stack to the new pipe also. In terms of the ventilation, it seems that your existing downstairs svp might be ventilated elsewhere along it's run? If so you can fit an air admittance valve (durgo) to your new en suite + do away with any external ventilation/pipework.

In all fairness tho, if I were in your position, i'd go with Expertboy's advice......... the easiest way

 

[bathjobby]

Or, at least re-design if possible and put the toilet where you plan to put the shower. That minimises your horizontal soil pipe and then run the smaller wasts from your sink and shower into it. When you buy the soil pipe 'elbows', you will see that they are 92.5 degrees and not 90, this angle gives you the fall required. And whilst you don't need planning permission for this work, alterations to soil stacks are notifiable, so you will need to inform your local BCO.