Waste layout options?

[Tony K]

Afternoon all. 

My SB uses piles and a floating slab, though which foul pipes will take waste water away to the sewer from two small bathrooms:

 

 

The bathrooms are 1600mm x 1600mm internally. Above the slab will be 90mm insulation and then 65mm screed (in which will live the UFH), plus the finish on top. 

 

I am now toying with the best way to arrange the waste pipes, including the best place to put the FWP. 

 

The walls are timber studwork, so I could possibly run a pipe from the sink through the wall to the bath and then under the bath, into the wall again, and then connect it to the w/c. Another option some have suggested is that the pipes from sink and bath are run through the screed and insulation, sitting on top of the slab in effect, but my concern is the effect of this approach on the thermal envelope and the UFH. Either way, it seems logical that the FWP should pass through the slab where it can be connected directly to the w/c. 

 

I am also giving some thought to installing a channel grate in the floor between the sink and w/c. I am not creating a wetroom, but nobody in my family seems able to have a shower without soaking the floor, so I could factor that in now. 

 

If anyone has any pearls of wisdom regarding the best plumbing layout, and the pros and cons of a channel grate I'd be grateful!

 

Cheers