In a bathroom remodeling project, I noticed the newly installed plywood sub-floor is flat but not level, which may cause issues when installing the shower and the sink cabinet (water evacuation and shower door and cabinet not properly aligned with the walls).
Now, Internet tells me I should level my floor with self-leveling compound (after having caulked plywood joints and applied a coat of primer). Also, Internet tells me that putting backer-board over that (when settled) will cause it to break when I'll add the screws to fix it to the sub-floor. And Internet also tells me I could self-level the sub-floor and NOT use backer-board.
I'm confused.
What is the proper way to level my sub-floor before installing my tiles?
Best Answer
You could do either:
Which you choose will depend on the degree of out-of-level
Self Leveler: self leveler does not need to stay intact after the backer board install. It can fracture and still completely support the backer board.. its got nowhere to go and it doesn't migrate or degrade.
My personal preference is to use self leveler and then use a crack isolation membrane.
(Ditra is my preference, comes in 1/8, 1/4 and heating wire support styles)