Joining 40mm to a soil pipe

[Gerrydelasel]

I haven't done any plumbing before, so I'm still learning about this stuff.
If I want to add a new 40mm pipe (bath waste) in the position shown in red, it looks like I can't easily add a new strap boss because there's no virgin pipe to attach it to, because that funny coupler thing is in the way, yes?
Does that mean I'm going to have to dismantle all the stuff in the photo and fit a new bit of doubled-sided boss pipe instead?

 

[JimCrow]

Fit another strap boss below the pipe clip.

 

[TicTac]

Go down vertically from the outlet, and then cut across to a convenient point below the pipe clip, using a strap boss as JC suggests.

Post a wider picture.

 

[dilalio]

Boss pipe is better.

 

[Hugh Jaleak]

Any connection opposite the WC branch needs to be at least 200mm below the WC connection anyway to prevent crossflow. Might be a bit close at the point of the red line, just come in lower and use a couple of 45's on the waste to drop it to required height.

 

[Gerrydelasel]

Post a wider picture.

Am I right in thinking that coupler thing has been added to join newer (upper) pipe work onto the older bottom length of pipe?

 

[TicTac]

Take it down at 45 degrees, and then in where the concrete lintel is, and shift the pipe clip.

 

[John D v2.0]

If you're going to exceed maximum falls for 40mm pipe, it's worth using 50mm pipe instead to avoid pulling the trap. Bigger or flatter pipe will let air back into the pipe from the stack so the water can fall out without bringing the rest of the water in the trap
With only a single bath on the branch it won't be a disaster, but generally vertical or 45 degree pipes don't sit within the standard falls.

 

[dilalio]

Am I right in thinking that coupler thing has been added to join newer (upper) pipe work onto the older bottom length of pipe?
View attachment 139275

It’s likely a slip coupling to allow connection between 2 fixed points.
Lubricating it with silicone spray or fairy liquid would get it moving.

 

[Hugh Jaleak]

No need to alter what's there, only making unnecessary work for yourself. Just fit a strap boss below the clip, and use a couple of bends to bring the waste to that point. Not much danger of pulling a bath trap, there is enough runoff from a bath to refill the trap once its emptied.

 

[John D v2.0]

Not much danger of pulling a bath trap, there is enough runoff from a bath to refill the trap once its emptied.

Agreed, I should have been more explicit with my comment about the single bath being ok - it would only become an issue if the op might add another appliance to the same branch later.

 

[Gerrydelasel]

it would only become an issue if the op might add another appliance to the same branch later.

Yeah I may end up adding the sink to the same branch. Currently it goes to the boss on the toilet pan connector but the toilet is getting rotated eventually.

 

[John D v2.0]

Yeah I may end up adding the sink to the same branch. Currently it goes to the boss on the toilet pan connector but the toilet is getting rotated eventually.

So the risk would specifically be that emptying the bath may cause enough suction to empty the sink trap, causing smells to enter until the sink is used next. Not to mention the annoying glugging noise.

It's up to you whether to try to preempt it with a bigger pipe/better falls, or you can use the catch all solution later of adding an AaV into the end of the branch when it's needed

 

[Hugh Jaleak]

Anti vac trap on the basin should suffice, really need to put one on mine!

 

[dilalio]

Anti vac trap on the basin should suffice, really need to put one on mine!

I think I need to put one on my dog’s arse! Phew!