Bathroom Wastes

[Simes123]

Hi, new to the forum, but have found it a useful resource.

Just bought a house and am finding a few "niggles". First of which was in the family bathroom. Went to adjust the shower hinge, only to find that the shower had been fitted incorrectly. To cut a long story short, I've ended up taking out the entire shower, all the tiles off the wall, including soggy plasterboard, and now discover what I think are some waste pipe issues.

Free standing bath has been plumbed in with waste pipe running in the studwork wall. First problem - 32mm pipe. Pipe has a normal fall, and then routes by a (very) low profile 40mm shower waste via a compression T, which has reducers each side for the bath waste to run through. So we have a shower, beneath the level of the bath, both sharing a 32mm pipe.

It looks like they had space problems in routing the waste, both through the studs and eventually through the floor (using flexi over a steel joist that is not friendly to the direction of the waste run)- I'm assuming that's why they used 32mm. It looks from what I've read that this is not compliant with building regulations, and given that I've gone so far, I'm about to take up part of the (18mm chipboard) floor to see if I can route things more sensibly, and over a shorter route (bath waste is prob running 3.5m).

I'm intending to run 2 x 40mm, independent wastes for shower and bath assuming I can achieve a better routing. Is this correct? The reason for my doubt is in reading the guide on here: //www.diynot.com/pages/pl/pl060.php which talks about 32mm.... If 32mm is acceptable in certain circumstances (or if I've misinterpreted something), it would save a lot of work.

First step tomorrow is to lift the flooring. The property is a converted church, and it looks like I have a lot of space under the steel floor joist from inspection with a torch. So even though it goes the wrong way, I may be able to get under it with sufficient fall.

Sorry for the length of the post!

Simon

 

[denso13]

I'm intending to run 2 x 40mm, independent wastes for shower and bath assuming I can achieve a better routing

If possible, this is the best solution.

 

[Simes123]

Thanks. Further investigations now I have part of the floor up, reveal the limitations that forced previous owner into the choices that he made. 32mm flexi, running over the steel support member at the end was the only location he could run the pipe.

However, to overcome this issue, I can build a raised floor for the bath and shower and have a step up to both. The layout is quite kind to it, and it neatly provides a box in which I can get over the steel I beam to a nice run to the soil pipe.

Question though - if I convert the soil pipe connection from 32mm to 40mm, will that suffice for both bath and shower if I join them with a swept T? Is it permissible to join them so? The reason I ask, is I'm not sure that I have enough access to convert one from 32mm and add a second. Appreciate any advice.

 

[Hugh Jaleak]

32mm is ok for basins and bidets, baths and showers should be 40mm.

You can join both with a tee, danger is bath could pull the shower trap when emptying, or should waste block, bathwater can reappear in the shower.....

 

[Simes123]

Thanks again.

OK, a further weekend on the project gone (missus loves me!).

I've settled on running the bath in 40mm (approx 2.75m long run) to a swept T, joined by the shower, which has a run of about 2m. The T itself is almost at the end of the run into the soil pipe. (another 20cm or so till the soil pipe.

It looks like this viewed from above:

Soil pipe
.....|
.....T
..../.\
../.....\
/.........Shower
Bath


In each run, I have to do a shallow step up to get over an I beam, like this (the angle is shallower):

---\
...I.\_____

If the above is ok, I have all the bits I need. My final queries are:

a) Should I source a 50mm swept T and 50mm pipe for the junction just before the soil stack (and conversion fittings for 40mm pipe to a 50mm fitting)?

b) Or b, leave it as is, because of the short distance from the T to the stack?

c) The engineer in me wants to leave it tidy and square, but I assume in wastes, less is more, so the diagonal runs in the plan view above, under the floorboard joists are ok as is? If I were to no run them directly and diagonally under the joists as shown, I'd be longer than 3m for the Bath.

Sorry for the questions

Simon

 

[Nige F]

32mm is ok for basins and bidets, baths and showers should be 40mm.

You can join both with a tee, danger is bath could pull the shower trap when emptying, or should waste block, bathwater can reappear in the shower.....

if you fit a Hep V O waste valve on the bath waste and inline one to the shower waste - assuming you have a shallow trap specialised shower waste outlet - you disable said waste/trap by removing the sleeve insert then the Hep valve takes over . Then you will have no problems .

 

[Nige F]

In each run, I have to do a shallow step up to get over an I beam, like this (the angle is shallower):

b) Or b, leave it as is, because of the short distance from the T to the stack?

Going over the beam is not good b) is OK. I`m thinking some pictures will help us