Geberit Confusion

[jack]

No, just a very powerful stream.

[Weebles]

Just doing some bathroom planning so this thread is really helpful.  We were thinking of the 112cm Geberit Duofix frame but we have two bathrooms next to each other and the toilets are currently back to back (design stage only).  This looks like it could cause a problem?  We could make a thicker internal wall between the two rooms to fit the two frames in back to back (?) but what about the soil pipes?  Even for a single Geberit frame with a toilet on an internal wall what width wall is needed to fit the bend of the soil pipe within the wall?  The frame seems to be 12cm wide but it looks like the soil pipe could extend wider than that?  Anyone got one fitted who can advise?

[Onoff]

  On 02/11/2017 at 20:51, Weebles said:

Just doing some bathroom planning so this thread is really helpful.  We were thinking of the 112cm Geberit Duofix frame but we have two bathrooms next to each other and the toilets are currently back to back (design stage only).  This looks like it could cause a problem?  We could make a thicker internal wall between the two rooms to fit the two frames in back to back (?) but what about the soil pipes?  Even for a single Geberit frame with a toilet on an internal wall what width wall is needed to fit the bend of the soil pipe within the wall?  The frame seems to be 12cm wide but it looks like the soil pipe could extend wider than that?  Anyone got one fitted who can advise?

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This is mine:

 

 

[Weebles]

Have you sculpted that soil pipe into your Celotex there?

[PeterW]

At a push the soil pipe will fit into about 150mm. 

 

 

 

The catalog shows the min/max of 90-135mm for the centreline of the soilpipe. If you add 55mm onto that then you’re at 145mm or about 25mm thicker than the cistern itself. 

 

https://catalog.geberit.com/public/product.aspx?cat=GB_GB-en_1&ch=CH3_100902&p=PRO_100833

 

If you are putting them back to back you may struggle with soil pipe separation to meet building regs. 

 

[Onoff]

  On 02/11/2017 at 21:41, Weebles said:

Have you sculpted that soil pipe into your Celotex there?

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The pipe was put in and expanding foam squirted around and flushed off. I had to add 9mm ply to the face of the studs to allow for the dia of the 110mm pipe collar.

 

I really don't know where to begin...you needed to have been here from the start of the journey...

 

It's a long story...ask anyone here!

 

Depending how bored you are:

 

https://flic.kr/s/aHsk23FYzd

 

 

[Weebles]

Thanks @PeterW that drawing has made everything alot clearer.  Are you referring to building regs for soil pipes joining the main stack?  I can't see anything referring to two soil pipes running next to each other i.e. before they join the stack....but then I haven't read the whole lot just yet.....

[Bitpipe]

  On 02/11/2017 at 21:52, PeterW said:

At a push the soil pipe will fit into about 150mm. 

 

 

 

The catalog shows the min/max of 90-135mm for the centreline of the soilpipe. If you add 55mm onto that then you’re at 145mm or about 25mm thicker than the cistern itself. 

 

https://catalog.geberit.com/public/product.aspx?cat=GB_GB-en_1&ch=CH3_100902&p=PRO_100833

 

If you are putting them back to back you may struggle with soil pipe separation to meet building regs. 

 

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We had this challenge on the kids bathrooms which are back to back. Plumbers concern was that if done incorrectly, flushing one loo would cause splash back in the other. In the end we needed to ensure adequate separation of the individual wastes (and therefore the loos) to ensure they both had a decent drop before coming together in a Y - part of the issue was the depth of the wall between them. Meant we needed to build out a small partition in one of the bathrooms.

 

[Nickfromwales]

  On 03/11/2017 at 07:33, Bitpipe said:

 

We had this challenge on the kids bathrooms which are back to back. Plumbers concern was that if done incorrectly, flushing one loo would cause splash back in the other. In the end we needed to ensure adequate separation of the individual wastes (and therefore the loos) to ensure they both had a decent drop before coming together in a Y - part of the issue was the depth of the wall between them. Meant we needed to build out a small partition in one of the bathrooms.

 

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To get 'splashback' out of an adjacent WC from another would be something I've never seen. I've fitted multiple WC's in nightclubs and hotels etc and they've been less than a metre apart in some instances. If the soils can fall vertically before any horizontal invert then the 'issue' is instantly removed. If you plan a T in between two rear exiting WCs which are DIRECTLY opposite each other then the worst you'd get is the water level in one being noticeably moved by flushing the other. 'Debris' would likely become apparent in the lesser used one over time, but I doubt anyone would ever T two together in such a way anyhoo as its not common practice. 

Offest the two WCs by 300mm or so and you'll be able to couple up to the same T using an 'intersection branch'  and the issue is done with there and then. 

One of these or one of these for eg, with the two WCs existing horizontally left and right into the latter as the first choice. 

[le-cerveau]

We have back to backed our kids en-suites to get over the issue of 2 toilets flushing through horizontally opposite wastes and will employ the layout shown below.  These are Gerbrit Duofix frames with a 100mm stud wall between.  The soil stack goes vertically down at the indicated point which may be your problem.

[Onoff]

A couple more shots of mine albeit a single pan. More to get an idea of the convoluted route I went to bring the soil run within the stud wall depth. My stud wall is odd in that to square the room off the studs vary in depth from 95mm where the soil exits the wall to 150mm down by the Geberit frame. I was sort of lucky as the frame sits over where was an old door way, now blocked up but with the face of the blocks recessed by about 2" from the original wall:

 

 

 

You can see here it was all looking good until I had to account for the collar thickness on the fittings. If you use push fit then the distance from centreline will be in excess of 55mm.

 

To gain mm I went solvent weld. (Measure, dry fit & mark, double check before you glue - not for the faint-hearted but I'd do it again). Even with solvent weld the horizontal brown was just that bit too far out past the stud line and immovable where it exited through the wall. Hence the 9mm packing pieces added above:

 

 

 

So now my moisture resistant plasterboard & Aquapanel for the wet room corner will "sail" over the soil pipe and be unsupported there - must remember NOT to screw there!  

 

 

 

Edited November 3, 2017 by Onoff

[Gone West]

  On 03/11/2017 at 07:47, Nickfromwales said:

To get 'splashback' out of an adjacent WC from another would be something I've never seen.

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I've used the Floplast double branch soil pipe you suggested for back to back connection of two toilets without any problem. I was told it wouldn't work but the BCO was happy because it was manufactured for that purpose.

[Nickfromwales]

  On 03/11/2017 at 08:22, PeterStarck said:

I've used the Floplast double branch soil pipe you suggested for back to back connection of two toilets without any problem. I was told it wouldn't work but the BCO was happy because it was manufactured for that purpose.

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The BCO will usually accept a demonstration of proper / reliable function  TBH. The proof is in the pudding. 

If I doubt they'll be happy initially with one of my 'get out of jail card' solutions, I cobble it all together and call the BCO out. 

They cant say it wont work when they can see it working  and they get the final say. 

[Temp]

When you push the WC up against the wall it tends to push the flush pipe back into the wall. I'd recommend a brace behind the flush pipe to prevent this. Likewise the soil pipe.

[Onoff]

  On 03/11/2017 at 13:55, Temp said:

When you push the WC up against the wall it tends to push the flush pipe back into the wall. I'd recommend a brace behind the flush pipe to prevent this. Likewise the soil pipe.

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You'd have trouble pushing these Geberit brackets off once clipped in! A bit of silicone spray on the pipe before it goes in etc.

[Nickfromwales]

  On 03/11/2017 at 13:55, Temp said:

When you push the WC up against the wall it tends to push the flush pipe back into the wall. I'd recommend a brace behind the flush pipe to prevent this. Likewise the soil pipe.

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Negatory .

The full frames have the cistern outlet moulded as a solid section of the cistern which faces forward. It's clipped to the metal frame and doesn't move a mm. 

 

The black soil bend is shown loose here, but gets locked into position by a horseshoe clip and doesn't budge. 

 

What you get left after boarding / tiling. The geberit supplied pan connector pushes into the larger hole, cut to length to suit, and likewise with the supplied flush pipe. Plenty of silicone grease on the ends and the pan slips onto them like a hand in a glove.  

 

Bingo. 

[Nickfromwales]

 

@Onoff s pic here shows it best. 

[Onoff]

Infamy!

 

EDIT: On my attempt the black goes into the grey and is push fit. Then it's grey to grey solvent weld. to get the "kick". Solvent weld fittings are just that bit more compact. The grey to brown joint, (where I didn't want a collar) caused me a few sleepless nights with questions over whether brown soil will in fact solvent weld to grey. The brown is more "plasticky" if that's a word, Thought they're all pvc thay have slightly different BS numbers. With hindsight I'd have done the long length in grey or black. Also, ref different makes of fitting, some joints can feel a bit loose. I got a tube of pvc gap filling cement. It's a bit thicker than the stuff comes in a tin with a brush. Shop around as it's pricey if you do need some:

 

 http://www.plasticdrainage.co.uk/clear-solvent-cement-gap-filler-7965.html?gclid=EAIaIQobChMI-ZOMuOii1wIVg7vtCh35VwHJEAQYAyABEgIimvD_BwE#fo_c=1765&fo_k=7ae12d9e5b724501290300d41070b52c&fo_s=gplauk

Edited November 3, 2017 by Onoff

[garrymartin]

Just posting this here for future reference when anyone is looking at back-to-back WC issues and the Geberit frames. There is a Geberit pan connector specifically for this situation. I found it when researching the back-to-back "challenge"...

 

 

[Annker]

  On 20/03/2024 at 12:16, garrymartin said:

Just posting this here for future reference when anyone is looking at back-to-back WC issues and the Geberit frames. There is a Geberit pan connector specifically for this situation. I found it when researching the back-to-back "challenge"...

 

 

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@garrymartin I now am attempting to solve the back 2 back concealed frame challenge, and very appreciative to find your post, as even Geberit themselves seem to be hiding this fitting from the public

Can I ask if where you found the Back to back frame diagram above as it doesn't appear on the product page on the Geberit website?

Did you actually fit two frames back to back 

[MikeSharp01]

  On 03/11/2017 at 14:54, Nickfromwales said:

The black soil bend is shown loose here, but gets locked into position by a horseshoe clip and doesn't budge. 

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That looks like the soil pipe runs up hill in the white flexi section is that allowed, acceptable, inevitable, to be avoided or what?

[Nickfromwales]

  On 15/03/2025 at 17:17, MikeSharp01 said:

That looks like the soil pipe runs up hill in the white flexi section is that allowed, acceptable, inevitable, to be avoided or what?

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The pan connector was laying on the floor  It was later lifted up and into the receiver, and clipped in, locking it into place with a fall.

 

I put some membrane against the wall, and pumped a load of foam under and behind the flexi so it couldn't ever drop / droop with time and use etc.

 

I only used a flexi there as 2x 45 or 30 or even 15 degree bends couldn't get me lined up right for a rigid installation.

 

[MikeSharp01]

Thanks Nick - sorry that pic was from 2017, I thought if it has been shovelling stuff up hill since then life must be fun somewhere!

[Nickfromwales]

@MikeSharp01

 

A shit pic, but shows the final fitment and a decent fall. Nothing went anywhere other than downhill I assure you 🤣

 

[garrymartin]

  On 15/03/2025 at 16:17, Annker said:

@garrymartin I now am attempting to solve the back 2 back concealed frame challenge, and very appreciative to find your post, as even Geberit themselves seem to be hiding this fitting from the public

Can I ask if where you found the Back to back frame diagram above as it doesn't appear on the product page on the Geberit website?

Did you actually fit two frames back to back 

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It was in the Geberit catalogue here https://catalog.geberit-global.com/en-GU/product/PRO_101639

 

Sadly we've not fitted anything yet as still fighting planning battles.