Quick question- need help ASAP: subfloor thickness?
I'm going to be laying 12 x 18 ceramic tile in my small (5' wide) bathroom. I've already checked John Bridge's Deflecto-lator and our joists are great. The existing subfloor is 3/4" diagonal plank (c. 1950's) and some messed up plywood, then tile. I already took up the old tile and we're removing the messed-up plywood part :)
I want to re-install new plywood. Then I will be priming, laying electric radiant heat, and using a self-levelling concrete, then thinset and tile.
I need to know what thickness plywood I should use. I'd like to keep the floor height as low as possible, but, of course, have it strong/stable enough.
3/8"? 1/2"? 5/8"? 3/4"?