Hi all,
I'm trying to get some recommendations for materials to use for a
shelf that would be attached to the wall next to my bathroom sink. I'm
disabled and really need to have certain things close by which is why
the shelves need to be right next to the sink. Problem is, the
particleboard shelves I've used in the past would always swell up and
crack over time because of moisture. FYI, they were the plastic
(Melamine?) covered shelves.

http://www.azek.com/products/trim/sheet

Various sizes available. Will last centuries.