Bathtub backerboard installation
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?