Potential en-suite: long waste run, crossing chimney breast?

[ritchieee]

Hello all,

I’d like to install a small ensuite in the main bedroom. It's a mid terrace property, with the main bedroom at the front, existing bathroom and soil stack at the back. I have attached a picture showing the existing layout, and on the right is what I’d like to achieve. The green line is the proposed soil and waste run, with the green circle being the existing soil stack. The black rectangles are chimney breasts, grey rectangles are built in wardrobes.

First problem, the soil pipe run from the ideal position of the toilet to the existing stack would be approximately 9-10 metres. My question regarding this is, could I install an air admittance valve after the additional toilet into the loft right above to legally get around the six metre regs, and also to eradicate any potential issues on a run that long?

Second potential issue, I’d like the soil pipe and waste to go through a chimney breast in the next bedroom. The chimney here is not in use on my side. That bedroom’s fireplace is bricked up and the one below it is also sealed. Is it legal and safe to take a soil pipe through this chimney breast (horizontally)? Interestingly, my plumber neighbour up the road has took a waste (not soil) through his and said it’s fine to do so (his is a detached house though, with a bigger chimney breast).

This would be my ideal route - the route has a chimney breast and a built in wardrobe, meaning I could box this in along the way without impeding on the back bedroom’s layout or space really.

The good news is my joists run the way I need them if I do have to go under the floors but I’d rather not.

Thanks

 

[Hugh Jaleak]

Firstly, you are going to need an absolute minimum of 100mm of fall across a 10m run, (based on a 1:100 fall), given there are 2 bends proposed, you really need more, so looking at the recommended 1:40, that'll be 250mm needed.

Secondly, I would be rather cautious about knocking too much out the chimney breast, it's supporting a fair bit of weight above, and may need additional support for the remaining brickwork above.

Long soil runs can work, an AAV at the head of the run is certainly advisable, but I would also give consideration to putting a second stack in, immediately where the proposed new soil pipe exits the rear of the property, and look at running it underground to meet with the existing drain. Will avoid at least one bend, buy you some room internally to play with falls as I think you may struggle there.

 

[Nige F]

Or consider a saniflo - smaller pipes through the chimney and run internally to near the external soil pipe - Now I'll wait to be flamed

 

[ianmcd]

Or consider a saniflo - smaller pipes through the chimney and run internally to near the external soil pipe - Now I'll wait to be flamed

Ha Ha you know its coming Nige

 

[ritchieee]

Thank you @Hugh Jaleak for your detailed reply. Appreciate you doing the calculations on that fall. I was hoping I’d get away with something between those two figures.

The problem with installing a second stack is that the area top-right you see on the diagram is a concreted garage so if that had to be done then I’d probably not go ahead.

I’m going to take a board up and see if avoiding the chimney is possible.

@Nige F a saniflo! :’( again I think that’d be a deal breaker if that was the only option

 

[ritchieee]

Thinking about this fall issue. The ceiling is about 2.5m, what about a step up en-suite? I have to step down into my bathroom in the middle of the night now anyway so I might as well break my ankles and land straight into bed…

 

[Hugh Jaleak]

It's a possibility, as long as you're short enough for it not to be an issue. Better than frequently trying to unblock a soil pipe anyway....