I am planning on fitting an en suite shower and baisin and want to run the waste from these to the WC waste / soil stack which runs down the opposite corner of the room (house is old with many modifications over the years and there are a large number of hidden voids above ceilings).
I can run the waste under the floor (parallel to the joists) but the existing WC waste bends and runs horizintally just below the joists so I do not have a vertical section clear of joins where I can fit a clamp on boss to take the waste pipe.
I do have access (just) to the horizontal section of the soil pipe where it runs above the ceiling below, can I fit a boss such that my waste pipe enters the soil pipe vertically from above?
I guess I'll need anti syphon traps on the baisin and shower wastes. Should I run these two wastes separately?