Help with waste/drainage design

[Annker]

Dear all, 

I would appreciate some help with designing a bathroom, ensuite and WC waste drainage layout in my renovation/extension project.

 

As illustrated in my markup I will have a downstairs bathroom (WC & WHB), bathroom (WC,WHB & shower) and ensuite bathroom (WC,WHB & shower) all located on the other side of the existing wall.

The plan is that all waste drainage will penetrate this wall and go to GL within a created service cavity, within the (yet to be built) extension block. 

At GL the drainage will be ran underneath the extension suspended timber floor, and exit to a new chamber.

 

My question is can these various wastes all join into a single main drainage stack (which will be vented through roof level) and a single drain run to the chamber, or should each bathroom have its own stack and multiple drainage runs into a distribution? chamber.

 

For simplicity have not included ~2 RW downpipes which were originally combined into the sewer drainage.

I'm unsure if BC/Bregs allow combination of RW and sewer in renovation work but I will confirm with my BCO. 

 

Extension drainage schematic.pdf

[Annker]

Spent the better part of the day researching many post here and I think I have figured out some more detail to the design.

To try simplify the things I have separated the downstair WC and WHB from the upstairs sanitary waste; both will join into the inspection chamber through individual inlets.

This also build in some redundances into the house, should blockages occur 

 

The upstairs draining is the more complex and I would appreciate any feedback offered to my sketch below.

 

The WC's will be "back to wall" with a "P" type trap.

A 90 deg rigid pan connector will join the pan to the 110mm branch pipe which will pop up through the floor.

I also have the shower waste connected into this branch pipe, unsure if that is ok, in theory any whether it is possible in practical installation terms either?

The 110mm branch pipes will penetrate through a brick wall into a created service cavity.

Both branch pipes will then both connect to a single SVP via a double branch.

  

I then have the WHB's exiting their respective bathroom in 50mm waste pipe and connecting to the SVP via a double boss branch above the WC double branch, my understanding is this is a preferred arrangement. 

 

Any feedback greatly appreciated!

 

 

[Mr Punter]

What you have shown looks OK.  You may be better going through the wall with the shower wastes and connecting them to the SVP with a boss rather than using the pipe from the WCs, which will likely be too high in any case.

[Marvin]

37 minutes ago, Mr Punter said:

What you have shown looks OK.  You may be better going through the wall with the shower wastes and connecting them to the SVP with a boss rather than using the pipe from the WCs, which will likely be too high in any case.

and the flushing of the loo can cause the shower trap to empty...

[Annker]

@Mr Punter and @Marvin, thanks for the comments.

 

Yes I did have the thought that separating the shower wastes from the WC branches would be a better arrangement although I also thought that with them being at more or less the same level as the WC their respective junctions on the SVP would clash with one another.

 

One way avoid that clash would be to put a 90 deg elbow on the shower wastes after they penetrate the wall and them return them into the SVP at a lower position.

That would introduce another 90 deg bend in their route but perhaps it is still a preferable arrangement to having them T into the WC branch, which as pointed out may not be possible in any case.   

 

[Marvin]

59 minutes ago, Annker said:

@Mr Punter and @Marvin, thanks for the comments.

 

Yes I did have the thought that separating the shower wastes from the WC branches would be a better arrangement although I also thought that with them being at more or less the same level as the WC their respective junctions on the SVP would clash with one another.

 

One way avoid that clash would be to put a 90 deg elbow on the shower wastes after they penetrate the wall and them return them into the SVP at a lower position.

That would introduce another 90 deg bend in their route but perhaps it is still a preferable arrangement to having them T into the WC branch, which as pointed out may not be possible in any case.   

 

If you do use 90 degree bends please use swept bends