Does anyone have thoughts regarding the use of two layers of 1/4 backer-board around a bathtub? The first would be installed to the top of the bathtub flange. The second would overlay to about 1/4 above the edge of the tub, in-filled with silicon caulking.
I am thinking that this would alleviate the need for shims and create a flat/plumb surface for the tile installation.
Any thoughts? Would you use some sort of thinset or adhesive between the two layers?
I'd avoid doing that. 1/2" is the way to go, butted to the top of the tub lip. You'll silicone the joint between the tub lip edge and the backerboard, and your tile will lap down to the desired height.
its simple..Use 1/2 inch cement board .The tile will just cover it all.If it wont you need to build out the walls plumb with some ripped lumber.If you have a table saw just rip a 2x4 down to whatever thickness you need to extend the studs out flush to the top flange.Vola problem solved.Just be sure to keep the walls plumb and level or it will make tileing a nightmare...