Bathroom Waste Layout

[stephen_lowfield]

Hi all, first time posting. I am doing a self build extension and I am struggling how to layout the waste pipes for the bathroom. I have currently got 2 110mm pipes coming in from outside which go into the same inspection chamber. 1 of them is connected to toilet and is attached to vent pipe through the roof. And the other one is connected to double basin (40mm pipe up the wall and then tees off to 32mm pipes), the shower using 40mm pipe, I have also strap boss onto the 110mm for the bath 40mm pipe. Do I need a AAV possibly on the 40mm shower pipe as it’s the longest run or don’t I need one as they will all have water traps?

 

[Hugh Jaleak]

Could you finish the question please then we may be better placed to help you.

 

[Scally-Ho]

Come in Q, your time is up!

 

[stephen_lowfield]

@Hugh Jaleak and @Scally-Ho. Not sure what happened there but I have edited it and completed it

 

[Scally-Ho]

Your shower waste will be okay if the fall is correct and it has its own connection into 110mm stack. The problems arise if the shower shares a common waste pipe with other sanitaryware.

 

[stephen_lowfield]

Your shower waste will be okay if the fall is correct and it has its own connection into 110mm stack. The problems arise if the shower shares a common waste pipe with other sanitaryware.

Thanks Scally. So it shares a 110mm run with bath and double basin.

 

[Scally-Ho]

Without viewing the 110mm run, I would hazard a guess that all would be okay due to the volume of air in 110mm soil pipe.

 

[stephen_lowfield]

Without viewing the 110mm run, I would hazard a guess that all would be okay due to the volume of air in 110mm soil pipe.

I have attached a couple of pictures. All 40mm pipes branching into 110mm. And the sink will tee off to 32mm for double basin

 

[Scally-Ho]

I would prefer to see the basins have their own connection to the 110mm.

 

[stephen_lowfield]

I would prefer to see the basins have their own connection to the 110mm.

Thanks Scally. I will have a look at doing that. Would you put a AAV at all anywhere?

 

[Scally-Ho]

If you are combining any wastes, then yes to all on a single combined common waste pipe. Easy now but a right pig after all has been installed.

 

[stephen_lowfield]

If you are combining any wastes, then yes to all on a single combined common waste pipe. Easy now but a right pig after all has been installed.

Thanks Scally. I will put one on before the trap for the shower as it’s the longest run. Will that be enough ?

 

[Scally-Ho]

Possiblly, but the better you can make the waste system before the floor goes down, the better.

 

[Madrab]

OK - Just to throw things into the mix.

The shower - being the lowest trap in the bathroom should be on it's own 40mm waste pipe. You don't want the basins or bath emptying into the shower if there's a restriction or pulling on the shower trap. Basins can hook in further down close to the soil pipe connection if no other option but increase the pipe to 50mm at that point.

Bath ideally hooks into the soil pipe on another connection, could be into the top of the toilet soil pipe via a boss branch.

 

[stephen_lowfield]

OK - Just to throw things into the mix.

The shower - being the lowest trap in the bathroom should be on it's own 40mm waste pipe. You don't want the basins or bath emptying into the shower if there's a restriction or pulling on the shower trap. Basins can hook in further down close to the soil pipe connection if no other option but increase the pipe to 50mm at that point.

Bath ideally hooks into the soil pipe on another connection, could be into the top of the toilet soil pipe via a boss branch.

Thanks Madrab. So I have added a very rough sketch of what it is like at the moment.