ᐅ Construction of the drywall partition for the washbasin in panel form

Good morning 🙂

I am currently planning the drywall partition for my bathroom.
On this, a washbasin countertop about 2.5m (8 feet) wide will be installed, which will hold a countertop washbasin:

What is the best way to build this drywall partition so that I can securely attach the supports holding the "countertop"?
Are standard 100mm (4 inch) CW studs sufficient if I cover them with a 22mm (7/8 inch) OSB3 board, followed by one layer of drywall? (Washbasin weight approx. 50–70kg (110–154 lbs))
Prefabricated washbasin support elements, like those from Geberit, are less useful here because I can’t make use of their mounted threaded rods.

Unfortunately, a DN40 (1.5 inch) drain pipe from the washbasin to the right exterior wall also needs to be routed through the vertical studs.

Do not attach the boards directly to the drywall panels themselves, but to a frame that supports the drywall. This is easily achieved with a wooden structure (similar to a mounting frame for a wall-hung toilet).

I originally planned to build the entire structure out of wood.
But then I saw the prices for laminated timber beams.

You mean to build a beam framework only in the 2.5m (8 ft) wide and about 1m (3 ft) high section, and then construct the rest using standard metal drywall studs?

This is how I would build it – but not using glued laminated timber; rather, plain kiln-dried structural timber. This way, it’s more affordable and can be worked with easily.

Wouldn't this warp over time, potentially causing cracks (especially on tiled surfaces)?

This is state of the art. There are no cracks, provided the wood is dry.