Bathroom Waste Layout

[Madrab]

Ah ok - if each of the fixtures is draining into a 110mm soil pipe then great. I should read the posts properly

Do be careful about the shower though, if it is draining into the end of the 110mm then ensure you have a significant fall on the waste. You want to avoid any backflow into the shower if anything blocks up. Any runs that are shared then best practices is to increase the pipe size by one, where they tee in together.

 

[stephen_lowfield]

Ah ok - if each of the fixtures is draining into a 110mm soil pipe then great. I should read the posts properly

Do be careful about the shower though, if it is draining into the end of the 110mm then ensure you have a significant fall on the waste. You want to avoid any backflow into the shower if anything blocks up. Any runs that are shared then best practices is to increase the pipe size by one, where they tee in together.

Perfect thanks Madrab. I will increase the fall on it as it’s currently 1 in 40.
Is it worth putting a AAV on the shower run just before the trap? As it’s a long run?

 

[Madrab]

As long as the run has a suitable fall, if you can get it somewhere around 40mm per M and have the waste run drop as close as possible to the trap, that'll ensure a good outflow on the trap. Then just ensure the trap design incorporates an air inlet on the top of the dip tube, then there should be no issue with syphoning. The tray won't be draining the volume that should cause a vacuum in the run, that would then pull on the trap, so run length isn't a huge concern unless its majorly OTT.

 

[stephen_lowfield]

As long as the run has a suitable fall, if you can get it somewhere around 40mm per M and have the waste run drop as close as possible to the trap, that'll ensure a good outflow on the trap. Then just ensure the trap design incorporates an air inlet on the top of the dip tube, then there should be no issue with syphoning. The tray won't be draining the volume that should cause a vacuum in the run, that would then pull on the trap, so run length isn't a huge concern unless its majorly OTT.

Thanks Madrab. Glad it’s good and I don’t need to rip it all out and start again

 

[Hugh Jaleak]

My only suggestion would be, to run all the horizontal sections in 110mm, bed on some fine concrete as required to ensure consistent fall, then reduce at, or just under, floor level to 32/40mm as required. What you don't want is the system blocking, the underfloor sections getting gunged up and no way of cleaning them.

I take it the underfloor drain run(s) can be accessed from the chamber outside?

 

[stephen_lowfield]

My only suggestion would be, to run all the horizontal sections in 110mm, bed on some fine concrete as required to ensure consistent fall, then reduce at, or just under, floor level to 32/40mm as required. What you don't want is the system blocking, the underfloor sections getting gunged up and no way of cleaning them.

I take it the underfloor drain run(s) can be accessed from the chamber outside?

Thanks Hugh, I will will be putting a bed of concrete to keep them from moving. Currently just got them sacked on common bricks for the time being whilst I get it all sorted.
Yeah there is a chamber literally just outside so all accessible for rodding