Help novice with new ensuite waste plumbing

[imsparticus]

Hi, planning a new ensuite as per diagram and would be grateful for some suggestions/advice.

The main problem I think I have is the distance of the shower from the soil stack as it measures approx 6.5 meters (running around the room) just to the new WC. You can’t see in the diagram but there is a cloakroom on the ground floor under the existing bathroom which has a full height false wall which the soil stack is in. I planned to run the new WC waste pipe down at a steepish angle as soon as it goes under the dividing wall between the bathroom and ensuite and connect to the stack lower down than the existing bathroom WC within the false wall with a swept T.
So the questions are:
1) Can I join the 2 basin wastes together to run as 1 and in 32mm?
2) Can I run the basin wastes inside the partition wall and connect to the WC waste at the 1st bend on the WC? If so would I use a boss and would that bend need an access point as well?
3) Can I run and connect the bath waste to the 2nd bend from the WC? As above would it be with a boss and would I need an access point there too?
4) Can I run and connect the shower waste to the bath waste so that I only have one waste pipe from the bath onwards in 50mm?

I know that the situation isn’t ideal but I would like some solutions/suggestions that are within building regulations or close enough that they get passed if possible.

Many thanks.

 

[Richard C]

1) Can I join the 2 basin wastes together to run as 1 and in 32mm?

You can but you will need to vent the branch of you will draw the traps; you will need to vent anyway as the run far exceeds Building Regs requirements for unvented branch lines; in fact except for the loo, they all do!

2) Can I run the basin wastes inside the partition wall and connect to the WC waste at the 1st bend on the WC? If so would I use a boss and would that bend need an access point as well?

You can do that, again as long as you vent the branch, if you don’t the traps will siphon every time you flush the loo

3) Can I run and connect the bath waste to the 2nd bend from the WC? As above would it be with a boss and would I need an access point there too?

Again it’s possible but multiple connections to a horizontal soil pipe are not ideal & you will need to vent the branch or the loo will siphon the trap. You need rodding access to clear blockages each pipe run must be accessible from one end or the other

4) Can I run and connect the shower waste to the bath waste so that I only have one waste pipe from the bath onwards in 50mm?

Yes you can do that but the shower trap will need venting or an anti-siphon (Hepvo) valve or, again, the trap will siphon when you empty the bath.

The arrangement is not good & you may well have problems with it & a BI may not pass it; what you really need a new stack & connection to the foul drain. There are several Building Regulations you need to consider & comply with which include connections to the foul drain system, maximum length of unvented branch lines, extractor fan, possible sound insulation if you have stud walls & any electrical work. The work your doing is also subject to a Building Notice submission, will need to be inspected & possibly witnessed tests before a compliance certificate is issued; no compliance certificate could give you problems in the future.

 

[imsparticus]

Many thanks for the reply, I know it’s not an ideal situation but it would be far better from my point of view to get it to work if possible rather than add a new stack. I may be able to get the shower/bath wastes down to a boss on the stack behind the ground floor cloakroom wall if it would help? But as I intended to join the waste to the 2nd WC 110mm bend which will have a good drop I cant see that making much difference?

Re, venting the basin wastes, would I need to use a 32mm aav or could I just use anti syphon bottle traps? Same goes for the shower waste could I use a 40mm aav or would the hepvo valve be a better option?

Re rodding access I can’t seem to find any bend fittings that have a boss and rodding access, would it be ok to include a swept T just after a bend to give access and one at the other end of the pipe to give access in the other direction? Also I’ve not seen any pipe bends that have rodding access for the inside of a bend (i.e. either end of the bath wall) they seem to be on the outside of the bend which wouldn’t give me access anyway.

Re the other building regulations, yes I’m working my way through those too. I also can’t seem to find any maximum lengths of vented branch lines only of unvented?

Extractor fans I’m aware of but as I understand it I don’t need additional sound insulation as it’s an en suite. And yes I have already informed building control via a building notice. Long way to go yet though.

 

[Richard C]

Many thanks for the reply, I know it’s not an ideal situation but it would be far better from my point of view to get it to work if possible rather than add a new stack.

New stack is what I’d go for; sounds daunting but, depending in the location of your foul drain, it would make things so much easier.

I may be able to get the shower/bath wastes down to a boss on the stack behind the ground floor cloakroom wall if it would help? But as I intended to join the waste to the 2nd WC 110mm bend which will have a good drop I cant see that making much difference?

Recommended practice is for a separate stack connection for each utility (bath, basin, loo etc.), whilst the odd top entry or daisy chain is unavoidable, daisy chaining all the waste connections into 110 soil branch pipe is not good practice & may not be acceptable to BI.

Re, venting the basin wastes, would I need to use a 32mm aav or could I just use anti syphon bottle traps? Same goes for the shower waste could I use a 40mm aav or would the hepvo valve be a better option?

Depends on precise layout, they will both do the same thing but sometime one is better than other. Showers are usually a problem because the waste is usually well below floor level, are you sure you can actually get the necessary falls with your arrangement?

Re rodding access I can’t seem to find any bend fittings that have a boss and rodding access, would it be ok to include a swept T just after a bend to give access and one at the other end of the pipe to give access in the other direction? Also I’ve not seen any pipe bends that have rodding access for the inside of a bend (i.e. either end of the bath wall) they seem to be on the outside of the bend which wouldn’t give me access anyway.

Don’t think you’ll find any small fittings with back access; use a tee with a removable cap instead of a bend; but if you use push fit instead of solvent weld, you can pull it all apart anyway!

Re the other building regulations, yes I’m working my way through those too. I also can’t seem to find any maximum lengths of vented branch lines only of unvented?

That’s because there aren’t any for water (non solid) waste but it’s usual to increase the fall the longer the run you have; don’t use anything less than 1:40 & that needs to increase the longer the run.

Extractor fans I’m aware of but as I understand it I don’t need additional sound insulation as it’s an en suite.

You don’t need sound insulation for the walls within the bedroom it serves but any stud walls dividing to another habitable room must be insulated. If you intend to do any electrical work & have them inspect/test, you must tell them BEFORE you start or they won’t have it.

And yes I have already informed building control via a building notice. Long way to go yet though.

Good man but before you go too far, discuss your plans with the BI as it’s him that’s gonna say yes or no.

 

[imsparticus]

Many thanks once again, I'll have a chat with the BI to discuss my options before I start I think, but I'm sure I will be back with more questions

 

[Richard C]

No problem