Geberit Vorwand WC element with UA profile

I am currently renovating my bathroom. The washbasin and toilet (both from Geberit) are to be integrated into a pre-wall system with Knauf profiles. This should not actually be a problem. However, it is recommended to screw a Knauf UA reinforcement profile on each side of the toilet element. I wonder if this is necessary with double cladding (2 x 1.25 mm drywall boards). Furthermore, the exact purpose is not entirely clear to me. The frame of the toilet element already consists of a sturdy square steel profile. This UA profile is then supposed to be screwed to the floor brackets in the profile rail. At the top, it would only be inserted into the sheet metal profile (UW profile). Does anyone have experience with this, or is double cladding sufficient for the load of the tiles?

Hello Ratzec,

two layers of 12.5 millimeter sheathing provide surface, but they do not replace stiffening. The WC element transfers loads into the frame and the fastenings. The lateral UA profiles limit deformation of the pre-wall and secure the loads under transverse stress. Knauf and Geberit recommend UA as flanking profiles, doweled at the bottom with floor angles and force-fit connected to the ceiling at the top. Simply slotting into a thin UW is botched. Additionally, crossbars at element height, decoupled bearings, and soundproofing strips are required. The tiles do not care about statics. The decisive factor is the stiffness of the substructure. If you want to dispense with UA, you need at least double CW studs and load-bearing sheathing with wood-based materials.

Good luck!

Hello Nauer!
Thank you for the technically convincing answer. The double cladding is already "fixed" in terms of dimensions. Since the profiles are screwed laterally to the already stable square profiles of the WC element, I still don’t understand what they are supposed to catch "more" there? Since the pre-wall will only be 1.20 m high, the UA profile can only end up in a UW profile. How is it supposed to be meaningfully and stably attached there?
Technically, the purpose is still not understandable to me, although I do not want to question the explanation.
What possible movement are the profiles supposed to catch exactly?

Hi Ratzec,

the UA profiles do not form the Geberit frame; they stabilize the pre-wall. You need a load-bearing rectangular frame; otherwise, the whole thing acts as a short cantilever. The test load at the WC is 4 kN. Without lateral UA profiles and a force-fit head connection, the front deforms unnecessarily. Solution at 1.20 meters height. UA at the bottom fixed with floor brackets. At the top, no loose insertion into a thin UW profile. Install a continuous UA head rail and anchor it to the raw ceiling or lateral solid walls via consoles. Alternatively, a freestanding pre-wall system with tested supports. Double gypsum board provides surface, not post stiffness. Cross rails at element height. Acoustic insulation tape at all connections. Gypsum board impregnated. Screw spacing tight.