which construction board in wet room?

[källare]

In the corner of my future bathroom, there's a vertical drain pipe, 3 copper pipes, a water meter, and a bunch of compression fittings near the ceiling. I plan to enclose these in a "shaft" using two construction boards and some wall studs and short studs. In this shaft, I will also build pull-out drawers so that I can inspect the piping and any potential leaks.

I'm now looking at which construction board to use for this purpose. Unfortunately, I can't use traditional waterproof boards because of the pull-out drawers in the "shaft"; they are too weak since there will be large holes in the board where the drawers are. Material-wise, if it weren't for the fact that it will be damp in the room, MDF or plywood would have been perfect.

Can MDF or plywood be used if they are primed and surface painted? Which of these boards is least affected by moisture?

 

[thomasx]

OSB is probably more suitable I would think. But if you just paint properly, it shouldn't be any problem, there isn't really much difference compared to any other piece of furniture that can be found in a bathroom.

Assuming, of course, that the waterproofing is on the "real" wall and the shaft is then built inside, similar to when you install a wall-hung toilet fixture.

 

[källare]

Well, I was thinking of wallpapering with fiberglass fabric and painting on the construction board, but I wasn't planning to have an additional board. The OSB surface is kind of rough, right? But you can smooth it with some spackling.