We are refurbing a bathroom, and are trying to figure out the ins and outs of the Building Regs. The sink is on the opposite wall to the (external) stack, and restrictions on floor structure mean we're routing the waste pipe around the walls to reach it. This takes us parallel to the bath waste.
A couple of questions for those with more experience than me:
- are we okay to add a 45 junction and discharge the sink into the bath waste pipe (40mm)? ...or do we need to keep both pipes separate (and punch lots of holes in our external wall and then somehow get them at sufficiently separate heights to hook them all into the stack while observing the rules about 200mm separation of offset branches)?
- the run from the sink to final discharge into the stack exceeds 3m - do we need to add an AAV to ventilate the branch?
Lastly, there is a separate shower. At present, the shower waste pipe runs internally straight from the trap to the corner of the room (about 2m, following the joists), then takes a 90 degree turn to punch through a joist and the outside wall to reach the stack. Is this okay? Can't see why not, but am getting paranoid!