waste pipe shower underfloor extension.

[Alltheones]

I’m having my extension built and will be adding a downstairs bathroom, the builder is putting me a soil pipe in wherever I want it and I’ll be doing the rest (I’ve done one before but not from new)

I’ve attached a rough lay out. My plan is to get the soil put directly under the toilet about 150mm out from wall so I can build a box for wall hung toilet and then getting a vertical drop drain with my impey aqua dec to drop the waste under the joist the use clips on the underside of the joists with spacers to get the fall I need too the soil. Same with bath but because the bath is further away it won’t fall to the same hight as the shower? and then the vanity which is on its own although vanity is wall hung so will drop into the wall first the 90 degree out the 90 degree turn (is there a max limit on 90s I can use?).
Is there such a thing as too much fall as everything lands at the same soil boss so if o put that low enough for the bath fall then make the other meet that?
also will the T in the bath and shower cause me issues with emptying traps? I’m getting a free standing bath so not sure if they come with a anti syphon trap, same with shower as it’s a impey tray it has its own trap not sure if it’s anti syphon or not.

anyway thanks in advance.

 

[denso13]

Is your Building Control officer approachable? Perhaps take their advice as he/she will sign it off at the end of the day.

 

[Alltheones]

Well because I’m only first fixing the pipe work for now as I can’t afford to finish it as a bathroom for quite some time I’m not sure if he will pass it off as a bathroom in this case as it will just be a store room with a Few waste pipes capped off in it and some capped off water feeds, I just need to get it at this point so it can be sheeted

 

[oldbutnotdead]

Yes there is such a thing as too much fall on wastel pipes. Download the approved docs and have a read, its all there.
There are length limits on all pipe types, not aware of any hard limit on 90 deg bends but as few as possible is always good.
Your BCO will be very much interested in checking pipework before you bury it, you'll need either scale drawings or actual pipes to show them though.