I am a beginner remodeling my 1950s bathroom (total gut) and have an issue with my floor. I replaced the old rotted wooden plank subfloor with T&G plywood. The plumber just finished the rough plumbing (installing the tub) and needed to shime the tub 1/2 inch on the outside of the tub. Silly me, I thought a 1/2 inch slope toward the drain would be a good thing. If I had know it was an issue I would have attempted to correct the issue when I was installing the subfloor. My question is how do I best fix the slope in the floor? Is a 1/2 inch too much to use self leveling cement, if not do I do it before or after I install the cement board? The cement board and tile will cover where the tub was shimed on the outside of the tub. Is it OK to have the tub leveled with shimes on the outer face of the tub? I have only seen it done on the inside.