Best route for bath & sink wastes

[feasty33]

Hi,

I'm in the process of renovating our bathroom and am trying to think of the best way to route the waste pipes from the bath and sink.

Unfortunately i don't have/know how to upload a picture, so i will try to describe the layout as best i can!

Running from left to right along one wall (external to rear) there is the bath, then the sink unit, then the toilet and then the soil stack.

The original bath waste pipe went from the bath at floor level all the way to the soil stack.
The original sink waste went above the bath waste and joined the soil stack slightly higher.
The toilet is on a 90 degree elbow straight into the soil stack.

I think i have 2 options.

1: Run the bath waste following the original route along the floor to the soil stack, but with a T piece under the sink unit to join in the sink waste.
(TBH there isn't a massive fall in the pipes level from bath to soil stack, but there was never an issue in the past and there appeared to be no standing water in it when i removed it.)
Also, should i box this in all along the wall, or will one single pipe not draw the eye that badly??

2: Take both bath and sink wastes straight out the back wall and join externally.
This will definitely look nicer inside, but i'm not sure what to do about connecting up to the soil stack, as its internal to the house, not external.


Sorry for the long winded post,
Any help gratefully received!

Dave

 

[tpt]

is the external soil stack cast iron or plastic? if its cast dont think about tapping into it unless you want to replace it

 

[Richard C]

The original configuration with separate stack connections is recognised best practice although if it’s above the floor it won’t look very nice. If it’s on the 1st floor & the joists run in the same direction as the pipe runs, you may be able to run between the joists (dontl think about cutting/notching them). Another method is to drop through the ceiling & run underneath, boxing the pipes in.

If you start teeing bath/shower/basin wastes together, you will get problems with siphoning unless you use either AAV’s or HepVo valves. Through the wall & outside to an external stck would be best but that would involve replacing the stack; you can’t really dive out through the wall & dive back through the wall again to connect up to an internal stack.

There are also Building Regulations governing things like maximum length of runs, fall, access for clearing blockages & permissible location of stack connections.

 

[feasty33]

Hi,

Thanks for the replies (especially as i've just realised i posted this in the wrong section of the forum!!)

After looking around online, i think that installing two HepVo valves is the way forward.
I take it i install these as close to the bath and sink as possible, instead of the usual traps?

I'll then just run one pipe across the back wall of the bathroom, boxing it in.

Dave