Garden room drainage...

[philx]

Hi folks,

I'm trying to work out drainage for garden room with 1 x toilet, 1 x basin, 1 x shower. Because the drain has to run several metres to get to the building, there is very little height to play with to connect into it.

I have attached a sketch of what I'm thinking of doing.



Basically the toilet connects into an internal stack with AAV at 450mm above the stack's bottom bend and then the shower and basin wastes go into a bottle gully further up hill.

Is this okay? Is there a better way to do it? I believe I can't connect the shower waste into the toilet stack as it would be less than 450mm from the bottom bend, so if something like this won't work I'm out of ideas apart from pumping it.

 

[Ermintrude]

Be fine just run a vent off end of shower run. Also the drains need to be in concrete joined to the slab .

 

[joni os]

Surround in concrete, is an esoteric question. Have seen concrete but also full shingle surround. Personal opinion is that under raft foundation to single storey structure, full shingle surround with pipes sleeved through raft works well with plastic. Concrete surround works best with clay or CI. pipes.

 

[philx]

Great, thank you both.

Am I correct in thinking that I need to use the gully on the left to get over this 450mm lowest connection to stack bit in the regs, or could I make a direct connection? This was my first preference as it would have all been below ground and neater.

joni os, have you seen a BCO approve a full shingle surround? Do they not get funny about damage from above if there's no solid protection above the pipe? It would actually be a help to me in this particular case, but the pipe - especially at the start of the run on the left - will be very close to the surface.

 

[joni os]

Protecting pipe close to surface can be done with precast slab that spans trench. As drawn your plan seems fine. Don't complicit things by making connection to stack below floor level.
Your basin can be bossed to pan connector. Shower outlets can collect hair etc. external assess direct to shower trap can simplify future maintenance.
If Building Control is your concern then footings, service lintels and rocker pipes may also come into play.

 

[philx]

Thanks joni os, yes it needs to be compliant, so I'm glad I seemed to understand what the regs were saying! Thanks for the heads up on the rest, I can design the rest of the foundations now the drainage layout is sorted.

 

[Ermintrude]

Stubs and rockers.

But also breaks in the surround every 2m .