"Nick Brooks" wrote in message
om...
Hi all

We have gutted our cottage as we are in the process of joining two
together. The new bathroom will be above the kitchen. We are planning
to fit a loo, sink, shower and bath in the bathroom and a sink and
dishwasher in the kitchen.

I'm planning to take the waste from the shower and sink together down
a 40mm pipe and the bath down another 40mm pipe. At what point can
they join the 110 waste from the loo before it goes underground?

what are the relevant building regs?

Does this look like a good plan?



Try and keep the bath and shower waste together, because the difference in
height between the sink waste and shower tray waste will give problems of
flow back. Yep. The sink may empty into the shower, then flow away down
the pipe.

A think a better idea, is to make the outflow pipe a decent diameter (50mm)
to take all three appliances and try to keep the running level toward the
outside stack as steep as possible and with the shower tray at the highest
point, and if it's behind a deep inline trap (110mm running trap), it will
prevent the backflow from all the appliances.

The difference in waste outlet height between the appliances is your biggest
problem, but is easily overcome by either keeping them all separate, or by
putting the lowest to the floor at the highest point on the under floor
outflow pipework.