Mounting toilet on lightweight wall

Hello and good evening!

In our bathroom, we will construct the wall mentioned below as a lightweight/drywall gypsum board wall.
It was supposed to be solid, long story, it’s not solid, better not ask.

On the right side of the wall "2" the toilet is to be installed. Geberit UP 320.
The drywall installer now says that the load of the toilet must be "transferred" to the side walls because the entire wall is not floor-to-ceiling and therefore does not have the necessary stability. He recommends using a GIS system to transfer the loads of the toilet to the side walls. Understandable to me.

The sanitary guy now says to put an OSB board in the back of the wall, then it also holds without GIS.

What GIS is can be found out quite quickly.
Only what such a construction costs for our desired location or where to order something like that, I have not found yet? Could one also build a construction of suitably stable wooden beams instead of the GIS system, which would then also be clad with gypsum board afterward?

What do you say?

GIS, wood, or nothing?

Regards

Appel

The answer is relatively simple, nothing is not possible. Wood certainly works but, well..... There is no way around GIS, that’s why they exist. Every plumber has them and they are available in every hardware store.

Hi

A concealed cistern for drywall is the solution.
Whether Geberit Duofix, GIS, or something similar almost doesn't matter.

Olli

Hello!

Thanks for your opinions!

Well, but you also have to secure the Duo Fix. On the floor and on the back wall. However, the back wall doesn't "hold" that much, so the idea/opinion was to attach the DuoFix to the side walls. But to get to that point, I have to "extend" the construction to the side walls.....