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Discuss Toilet Waste Not Aligning With Wall Hung Unit in the DIY Plumbing Forum area at PlumbersForums.net

Messages
34
Hi Everyone

Just looking for some advice with this issue I have with a wall hung toilet I am adding to my bathroom. The problem I have is that when I set the ideal height of the toilet (410mm when sitting on toilet) and taking into account tiles and hardibacker (approx 30mm?), the waste pipe that was setup for my old toilet is going to be too low.

There are two options

I keep the frame where it is or swap it around with the basin frame. Swapping it around with the basin frame would allow me to use the original fall of the waste pipe but I may have to raise it 5mm or so to align so not sure if that is going to make the fall too much? At the moment with the current waste pipe the fall is approx. 38mm per metre. The current run of the grey waste pipe to the stack is only 1m and I would be adding another metre onto this pipe if it was to be extended.

The other option is to keep the frame where it is planned to go (first picture below) and work out a way of connecting the toilet connection to the waste system problem is i cannot lower the frame to meet the soil pipe as it will then mean the toilet will be sitting too low on the floor. At the moment it looks like I would have to raise the soil pipe another 10mm or so to get it to meet with the frame. Thats then going to increase the fall to 48mm per metre. Its only a 1.2 metre run to the stack so not sure if you can then 'get away' with a slightly higher fall...

If I do swap them around to make the connection of the waste to the toilet easier, then I will have to move the basin waste (you can see it behind the frame in the second photo). Another option is if i move the basin then I could put the basin waste into the soil pipe but not sure if you are allowed to do this? I would then just blank off the old basin waste coming out of the floor.

First picture shows the frame in the normal position showing the waste pipe alignment and the second photo shows where I could move the toilet to and have set up a rough position of the waste pipe from the frame to show how it would fit if i was to extend the waste pipe.

thanks!

IMG_8966.JPG IMG_8952.JPG

IMG_8969.JPG IMG_8967.JPG
 
Messages
574
In my view raising the connection 10mm or so will make no difference at all.
Also if you want to connect basin waste into toilet connection just use a strap boss I would then use a anti vac trap on basin.
 
Messages
34
In my view raising the connection 10mm or so will make no difference at all.
Also if you want to connect basin waste into toilet connection just use a strap boss I would then use a anti vac trap on basin.

Ok thanks for this so if I move it to where the basin is I will probably have exactly the same fall as before but then connect the basin waste into the waste pipe with a strap boss and then add an anti-vac trap onto the basin.
 

Ben-gee

Esteemed
Plumber
Messages
2,093
If you don’t mind swapping it’s position then that is probably easier.

Having said that, in your first photo it’s pretty close - if you try removing the two soil pipe clips you may find there’s enough play to get the connection. A little trick is to cut the horizontal pipe and then rejoin it with a connector just tweaking the angle slightly off straight. This will definitely give it to you. Don’t worry about the fall, it’ll be gone.
 
Messages
34
If you don’t mind swapping it’s position then that is probably easier.

Having said that, in your first photo it’s pretty close - if you try removing the two soil pipe clips you may find there’s enough play to get the connection. A little trick is to cut the horizontal pipe and then rejoin it with a connector just tweaking the angle slightly off straight. This will definitely give it to you. Don’t worry about the fall, it’ll be gone.

yeah just looked at it again and I think its worth trying to raise the waste pipe another 10mm or so than moving it across. Its not a great as the waste pipe is dictating the height of the toilet but have to live with it. I am allowing approx. 20mm for tiles, adhesive and tile boarding for the floor not sure if I need to allow more than that?
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
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28,799
Solutions
1
Have you picked your tiles already ?
Would allow 6mm for hardie, 5-6mm for bed plus tiles

so if there 8mm your 20mm is spot on
 
Messages
34
Have you picked your tiles already ?
Would allow 6mm for hardie, 5-6mm for bed plus tiles

so if there 8mm your 20mm is spot on
No not yet maybe I will have to reduce the thickness of the hardie as I was accounting for 10mm board for the floor. I was looking at the abacus elements floor kit and said the minimum size for the floor is 10mm not 6mm but maybe its overkill?
 
Messages
34

Aslong as there’s no bounce / deflection in the floor which I don’t think there wood be as it looks like a new floor ?

Thanks for the link will have a look

There is a bit to be fair as one of the panels has been replaced so maybe stick to 10mm to be safe. Eating into my soil pipe height though - always a compromise!
 
Messages
34
So I now have extended the waste pipe and it fits perfectly with the original fall extended out to it.

The next problem I have is the frame is sitting too shallow in my boxed area. I need it to sit around 20mm further out from the wall but the 90 degree connector is dictating how far the frame sits. I'm not sure how on earth I am going to be able to move the frame out any further from the wall as the soil pipe distance from the wall is fixed and the 90 degree connector is fixed. I almost need a telescopic one so that you can then change your depth from the wall when it is clipped onto the frame.
 

Ben-gee

Esteemed
Plumber
Messages
2,093
Should have used a geberit frame, the 90 degree pipe has about 6 different depth positions!!!! Not very helpful now, I know.

There will be enough play in the 4” to gain 20mm across a room don’t worry.

What you need to do is;

1) unscrew the soil pipe clips

2) position the frame where you need it and fix it firmly.

3) reattach your pipe clips to the wall using shims/ bits of ply etc of the appropriate thickness.
 
Messages
34
Should have used a geberit frame, the 90 degree pipe has about 6 different depth positions!!!! Not very helpful now, I know.

There will be enough play in the 4” to gain 20mm across a room don’t worry.

What you need to do is;

1) unscrew the soil pipe clips

2) position the frame where you need it and fix it firmly.

3) reattach your pipe clips to the wall using shims/ bits of ply etc of the appropriate thickness.

I measured everything before purchasing but never thought to even consider the waste pipe measurements! The installation videos are funny - the soil pipe is vertically below the frame in the precise location it needs to be...

I purchased the 'distance pipe' that grohe do to see if that would space it out but its taking it too far out. Either way you have just saved me a massive ball ache so thanks for that. I have managed to move the pipe around 15mm so that it aligns with my old studwork.

Just in the process of making some spacers for the waste pipe brackets now with some ply. Next time I will be using the Gerbeit one.

I am tempted to put the bracket on top of my studwork sole plate to spread the load instead of using bits of ply on the floor. Is there any issue with doing that? I will then drop the frame height to account for the stud height..
 

Ben-gee

Esteemed
Plumber
Messages
2,093
No that’s fine I usually do that
a) get the best fixing - into wood, b) gives you something to screw your 12mm hardiebacker to ( that’s the best thing to clad in if you’re tiling by the way)
 
Messages
34
No that’s fine I usually do that
a) get the best fixing - into wood, b) gives you something to screw your 12mm hardiebacker to ( that’s the best thing to clad in if you’re tiling by the way)

Yes I have some C16 studwork to use and will run it all the way across (as opposed to gaps for where the toilet and the basin is) and do the same with the basin frame. Good point with the extra area to allow you to screw the hardiebacker to - I suppose the more support for the boards the better.

I was thinking of using the abacus elements board kit 12mm but it seems fairly pricey to other non branded hardie backer board.

I have the abacus wall mounted basin frame to fit next hopefully more straight forward than the toilet has been.
 

Ben-gee

Esteemed
Plumber
Messages
2,093
Those type of boards don’t give enough support for the wall hung pan - ok if you have massive tiles or use thick boards.
12mm hardie is excellent structurally.
 

Ben-gee

Esteemed
Plumber
Messages
2,093
Any of the cement faced extruded polystyrene type will not be sufficient at 12mm thickness (unless supported at , I think, 300mm centres) .
 

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