Minimum thickness of stud wall with this toilet frame in it?

[Adsibob]

We are having to make a last minute change to the position of a toilet because where we were going to put it, the soil pipe would crash into a steel almost immediately upon exiting the frame.

 We have found a solution we think, but it might mean returning the Grohe Rapid SLX toilet frame I’ve already bought. All depends on how thick the stud wall has to be to fit it. Below is the drawing from Grohe. With a 110mm soil pipe what is the minimum depth that my stud wall, including hardibacker, adhesive and 6mm tiles on one side, and plasterboard and skim on the other side?

i just find this drawing very confusing. 

 

[Oz07]

I would say around 140 structural plus board and finish. Thinks it's the sizes second from the bottom you need to refer to. The waste pipes from these are not 110mm till they go below the floor. 

[Temp]

+1

If the pipe has to go horizontal then a bit more needed for timber to support plasterboard on back side of the wall. Say another 20mm?

[PeterW]

What’s on the other side of the wall..? I would want to get 25mm acoustic fibre (regs requirement) and possibly use sound block board too - so I would use 200mm

[Adsibob]

Other side of the wall is the first floor landing. We were planning to put a shallow cupboard in that wall so that sheets/towels could be accessed from the hallway. I either have to lose that cupboard or go for a much slimmer frame. 

[Nickfromwales]

@Adsibob

You can get the slimline Geberit into a 100mm void. No issues with sound transmission as the WC doesn't back onto a habitable room  Acoustic PB, possibly two layers on the reverse will suffice, plus any acoustic wool that you can stuff into the voids will help out. Remember not to touch anything that attracts condensation!!

I fitted one like this for 21 stone powerlifter, and substituted the 100mm timber ( old skool 4" stud there to start with as this was a refurb ) with 100mm x 50mm box section steel either side of the frame, lined with more timber to allow the frame to be affixed iirc. Steel was also used for the footer and the header and that did not move 1mm,. even with me stood on the front edge of the pan with both feet bouncing my weight gently up and down.

[Nickfromwales]

 

Bingo.

Edited August 2, 2021 by Nickfromwales