Connecting shower waste to 110mm drains

[HandyAndy]

As part of renovations, we are putting an en-suite in. The original plan was to use a single stack which would be used for basin, shower, WC. Unfortunately the subcontractors put the new drain connection too high to allow the shower to be connected to this ... As a result, the proposal is to make the shower run separately to the outside 110mm drain, where it would connect towards the top of the pipe.

 

Apart from the shower, all connections are to an internal sub stack with AAV. For the shower, the plan is to use 45' bends for flow/ rodding purposes.

 

I think this is OK (certainly from a technical perspective) - though before going too far would like to test people's thoughts on how this may be viewed by building control. I've tried reading building regs though didn't get too far with them ... for what it's worth, we are in Scotland though assume the principles are the same as England! Cheers ...

[ProDave]

Is there not a branch where the vertical grey pipe and the sloping brown pipe from the WC meet that you can connect into below the floor further to the left?

[HandyAndy]

Hi - thanks for the fast reply. There is a branch though it immediately goes into a rest bend. I don't think I can get a connector in there as the only options are the collar of the rest bend (too big), and the bend itself (too curved!) hence the approach of taking a separate shower waste out and joining outside.

[ProDave]

What about the actual branch connector, there is usually a boss on the side of those.  Photo?

[stu w]

Dig out around the 110mm pipe, fit a branch and come across to fit a proper gully , then take your waste into that 

[HandyAndy]

Yep, there's a boss on the branch - problem is that's above the height of the shower waste! - hence the need to take an alternative route out.

[ProDave]

Is the boss actually above or below floor level?  Can't tell from a picture looking down.

[HandyAndy]

sorry for quality of pic - best I could do with the angles available ... the top of brown below-ground drain is essentially at finished floor level - the grey branch and pipe are above floor level.

[Nickfromwales]

1 hour ago, stu w said:

Dig out around the 110mm pipe, fit a branch and come across to fit a proper gully, then take your waste into that 

Yup. 
@HandyAndy, you cannot connect to the underground pipe with that boss strap. Completely against b regs. 
You need to expose more, get a 110mm Y branch (not a T branch) and then extend a new piece of 110mm pipe to a gulley pot underneath where the shower pipe exits the wall (as close as you can get it).

You need to approach your building control person BEFORE going any further. 

[ProDave]

I take it that existing brown pipe through under the wall and it's rest bend are old (you say it's a renovation) so not a case of someone making a mistake but trying to find the best way to work with what was there.