Have 3 onsuite bathrooms on 2nd floor that have been gutted.
All 3 onsuites run along the same wall. ( Roughly 3 metres apart)
So that I am in line will building REGS PART H

Do I have to have one vented primary stack and the other 2 stub stacks fitted with air admittance valves? If this is the case , what is the termination height of the stub stacks.

or

Can I simply increase the size of the discharge pipes and connect directly up to the primary vented soil stack

Also

Is there a minimum distance apart that appliances can be connected to a branch discharge pipe.

Cheers