Soil stack connections

16 Mar 2006
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United Kingdom
Hi Im currently doing my bathroom and ensuite so wanting to check the soil stack connections.

the soil pipes are existing and im moving one of the toilets in the bathroom by 90degrees onto another wall.

i plan to install a bend into the vertical stack for toilet number 1 this will be run above the floorboards.

The existing soil stack is running in-between the floor joists and I just want to check that the connections are ok

i have attached a drawing and hope that it explains plus a photo of the existing pipework

Is it ok to have the bath waste bossed into the middle onto a horizontal run of the soil stack. Toilet number 2 is at the end of the branch.

I cannot get to the vertical part of the stack as the bath waste comes through the joist at 90 degrees to the soil pipe. and there is a joist in the way

IMG_9751 2.JPG

this is all under the floorboards apart from where im going to install a Tee into the vertical stack. This will be higher than the horizontal run

IMG_1252.JPG IMG_1253.JPG IMG_1256.JPG

you can just about see the bath waste appearing through the joist on the other side of the pipe. The tee pokes up through the floor where toilet number 1 use to be I want to remove this and install a plain bit of pipe and use a boss to connect the bath waste to this

does this all seem ok ?

this is how it has been installed when the house was built so i guess it should be ok but looking for re-assurance

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Your bath pipe should ideally enter the top half of the main pipe but as long as you don't enter opposite a branch into a horizontal run it should be ok.
It's hard to relate your photos to the diagram.
Draw a diagram of your intended plan so we can check.
I have tried to drawer a plan but im not the best at that lol i have attached the drawing above.

how can you fit the boss in the top half of the horizontal run ? as the boss fits onto the pipe and it sits in the middle if you follow me

what im looking at doing is removing the tee pice that goes up through the floor ( the one the bath waste goes into) and replacing it with solid pipe. then installing a boss in the side of the horizontal run for the bath waste as it appears through the joist

hoping the picture below paints a thousand words lol
oh right yes that's fine.
When you said the photos were under the floor boards, I thought you meant you opened the floorboards and photographed them below. Now I realised you are actually looking above the ceiling downstairs! That's why I had no idea what the photos were in relation to your drawing.
Regarding the entry point into a larger pipe of a smaller one, you have a choice of 360 degrees around the pipe of where it enters, although it always enters perpendicularly. You are supposed to always enter in the upper half, to prevent backflow into the smaller branch and blockages.
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John thanks for your advice.

I’m now fitting the new bend and new toilet in the bathroom above. The vertical soil stack goes up through the bathroom to vent into the loft space.
At the same level as the floor there is a join in the pipe so I am intending to split this, insert a 90 tee and install a new toilet.

There will be a small length of pipe and then the toilet. I brought a 90 degree pan connector but it isn’t deep enough to sit on the pan itself and bend 90 degree.
It would fit if I was taking the soil pipe to the floor but unfortunately I carnt do that as the joists run the wrong way

Do you get a extra deep pan connector or should I use a 90 bend onto the soil pipe then a straight pan connector into this

I’ve attached photos to try and show the problem

EE86FAA6-3CEA-4780-98D0-DC4642446972.jpeg 4955DE34-15FE-4B0E-B6DA-68B324EDFA8C.jpeg 52BF9616-F792-4B4B-A992-EF21497B7170.jpeg
I’m further on and now replaced the old soil pipe with new connections to suit the new toilet layouts

One question I do have and think I know the answer but just thought I would check.

The soil pipe straight goes up into the loft and through a tile vent. This was boxed in I’m the bathroom

What I want to do is put 2 45 degree bends and kick the vent pipe over into the other room where there is an empty void this way I can just box in the lower part and keep the corner clear

I’ve attached a picture to hopefully explain

The red line is the new soil vent pipe going into the wall and to the other side of the wall

The T piece is staying there as there is going to be a toilet under the window

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