Combine shower and sink waste?

[Luggsey]

Hi all, more questions sorry.
I'm installing en suite showers with 1 1/2" waste and wondered if it's ok to tap into the shower waste with a t for the sink?

 

[rpm]

Not advisable, two seperates always better. Hope you get your house finished soon!

 

[Luggsey]

Not advisable, two seperates always better. Hope you get your house finished soon!

I'm a bit stuffed then! The soil pipe has a fitting with two boss holes and I have two sinks and two showers to connect?
Hmmm.
House will take for ever!

 

[Luggsey]

Ok, worked out I can get each shower on it's own pipe if I combine both hand basins to a separate 1 1/2" pipe on a strap on fitting.
Two sinks on a 1 1/2" has got to be ok hasn't it?

A separate question, I have three en suite showers almost back to back, can I use one set of non return valves to feed all three? Going to be a bugger otherwise and expensive....
Cheers all.