[MartinK]

I am enclosing a shower doorway with marble, 6" marble threshold, sides and top. Into this I will be hanging a glass door.

Problem: The doorway is square however I failed to notice that one of the vertical 2 X 4s has a bit of a curve in it. Cement board has been installed but when I hold up the vertical marble slab there is a 3/8" gap between the center to the 2X4 and the center of the slab. This gap reduces to zero from the center of the slab to each end. Can I just fill this gap with thin set or do you have some other ideas?

 

[Ron6519]

You have two options. You can shim the cement board to a level plane or build up the thinset.
I'd shim the cement board so the thinset wasn't so thick.
Ron

 

[MartinK]

Thanks. I think I'll shim the cement board first as you suggest.