Soil stack alteration - is this OK?

Hi all,

Just want to check whether what I'm doing is

1- Not a really bad idea
2- Compliant

I'm changing around the layout of my upstairs bathroom and have bricked up the old soil, shower and basin waste holes and removed the hopper and separate downpipe that the old shower and basin wastes fed into. Now I need to pop a new toilet soil pipe through the wall and connect it up.

Ignore for now bath waste temporary resting in the existing tee, that's just there so I could finish up the bath/shower plumbing and test it out.

In red you can see my planned arrangement. Toilet waste will come out about 200mm to the side of the existing soil stack, drop vertically down (via an access elbow) and join into the soil stack lower down using a 45 degree Y branch.

The bath/shower waste will then boss into the side of the new vertical section.

As long as the bossed in shower waste is >150mm below the toilet waste level, is this an OK arrangement?

 

Looks ok, can you not just come out with the WC waste and go horizontally into a branch? Perhaps too close?

 

Yeah I'm thinking it might be too close to make the turn but I'll have to just buy the access bend and attach it to see.

Seems like I've got a suitable solution either way though.