I will shortly be installing a shower cubicle in my bathroom. I cannot place
the drain below floor level (because the joists run the 'wrong' way!', and
so will have to use a raised 'Easy Plumb' shower tray which should give me
the necessary 'fall' to the soil stack which is in the opposite corner of
the room to the shower.
To gain the maximum 'fall' possible I want to use a shower waste trap which
places the drain pipe as close as possible to the underside of the tray and
hence as high as possible off the floor at the start of the run. The
problem is that most shower waste traps have a shallow 'seal' and, where the
drain goes directly into the soil stack, I understand that this is not
acceptable and there has to be a deeper seal ( I have been variously quoted
50 mm and 75 mm - anyone know what the true figure is?).
There are a couple of ways around this problem - I could fit the shallow
waste trap to the shower tray - but also install a deeper 'running waste
trap' somewhere along the run - most obviously where the pipe runs behind
the bath panel. I can cut out a section of floor board and drop the 'U' of
the running waste trap into the void.
Another alternative is to use a HepVo trap - either on its own, or in
addition to the shallow waste trap. Does anyone know if the 'membrane seal'
design of the HepVo is acceptable under Building Regs as an alternative to a
deep seal on a conventional waste trap?