Soil and waste pipe queries for ensuite

[JamieG1985]

Good evening all,

 

First post from me. I've discovered this forum whilst carrying out some research for an ensuite renovation I have started. I'm a design engineer (toolmaker) by trade so not a plumber by all means but have done quite a bit of DIY on my own house. I like things done right and enjoy having a go myself, hence why I am here for a bit of advice.

 

I'm looking for some guidance in regards to the best method of connecting the pipes for the shower and hand basin into the soil pipe.

 

Currently, there is a horizontal soil pipe in the ensuite running under the floorboards which is connected to an internal vertical soil stack in our garage. The toilet is connected to the end of the run, then a bit further down is a 32mm pipe for sink waste which is connected into the side of the horizontal soil pipe, followed by a 40mm pipe for the shower trap further down again, which enters the horizontal pipe at the top and finally the bend into the vertical stack.

 

There is currently no AAV which I think there should be reading other threads. Please correct me if I am wrong. When we first moved in, the shower in the ensuite wasn't used as there was another one in the main bathroom. Over time the shower started gurgling as I think the water had been sucked out of the trap from flushing the toilet. We refurbished our bathroom a few years ago and replaced the shower in there with bath so we started using the shower in the ensuite again and we never had the issue again and has been ok since. Most probably because we use the shower everyday. 

 

I have attached a few diagrams for reference - 1) Current pipe layout (No AAV). 2) current pipe layout with additional 2x 50mm runs with 2x 50mm AAV which will run internally in wall up into attic. 3) Alternative pipe layout with a 32mm pipe run from the sink waste which will tee into the 40mm pipe from the shower and then run into the garage and connect into the vertical stack in the side. I'm not sure if it is possible to do this yet but could be an option if it is.

 

I have a few questions...

 

1. Is there anything wrong with the current pipe set up with the 32mm waste going into the side of the horizontal soil pipe and 40mm entering the top as this maybe my only option? I have read some conflicting views about connecting into the side rather than the top, so I'm interested in having some feedback. It's never been a problem other than the gurgling we had when we hadn't used the shower for some time and no noticeable foul smell. Just to point out, I have to replace the soil horizontal section as there is a crack in it. I will be using a mcalpine high flow shower trap and an anti syphon bottle trap on the sink.

 

2. Is an AAV required in my situation? I can't see a way of fitting a 110mm AAV without it becoming unsightly in the room as there is a doorway right next to the toilet. I have read in another thread on here and a work around suggested by @Nickfromwales is to run 2x 50mm individual pipe runs with 2x 50mm AAV which can be fitted before the bend to the vertical soil stack. He explained there is a natural air break in the horizontal section and only creates a vacuum when the water quickly travels down the vertical so the 2x 50mm pipes can be connected just before the bend into the vertical. Is this the same in my case? The shower tray is raised so I could run these under the tray and up through and internal stud wall into the attic so could do this quite easily. @Nickfromwales I would be very grateful for your feedback on this point.

 

3. I believe it would be better to run the sink and shower waste into the vertical stack via a boss strap but I'm not sure if this is possible yet without lifting the floorboards. Would this be the preferred method if it is possible.

 

4. My shower mixer controls will be placed centrally on the back wall. The original shower controls and pipes are offset to the right (photo attached) but now the hot pipe will be relocated more to the left and will be close to an electrical socket which is in the room behind. Will this be ok as I'm not sure of the regs. There will be a soldered elbow connection above socket height but to the right of it slightly so will only be an issue if it ever leaks. I could possibly move the socket to the left if required so it's further away from the new pipe position.

 

I will upload some photos of the room as it is for reference. I'd like to point out that the holes in the floor and joists are not my work and were discovered when I removed the boxing in which was purely there as a cover up. I have new boards to go down so it will be all good when I've finished.

 

Any feedback or advice is welcome.

[JamieG1985]

[JamieG1985]