110mm soil pipe, how to connect 32/40mm drains?

[oh]

Hi all,

I know you can get a "strap on boss" to connect your 32mm or 40mm wastepipes to your 110mm soilpipe, however what do you do if there is no space for one? At the floor level I have the tee for the toilet, a bit higher up the boss for the bathtub, a bit higher up the boss for the handwash basin, and a bit higher up there's an inspection part.

I want to put a separate shower cubicle in the corner, however there simply is no space for the connection to the soil pipe, that would be low enough.

Now, looking at the 110mm tee for the toilet there are four (two on each side) "pipes" sticking out, but not bored through, offset at 90 degrees from the toilet waste. These are

[oh]

[Andy Burns]

[Roger Mills]

couldn't you join the shower and bath waste pipes together before they reach the stack?

[oh]

I can join the shower and bath waste pipes together before the soil pipe however wouldn't there be a risk that water would come back up the shower trap if I fill the bath and lift the plug, or that the suction of the bath water drains it?

[Roger Mills]

I suppose there's a slight risk that a gush from the bath could 'pull' the shower trap. The other way round, if a bit of bath water temporarily enters the shower tray it won't do much harm - but it's not particularly likely anyway. I have shower and basin (admittedly not bath) wastes combined with no problem whatsoever.