installing tile over heated floor wiring
My bathroom floor from top to bottom consists of joists 16 in apart, a layer of 3/4 in plywood, and a layer of 1/2 in plywood (exterior grade). I have checked the level and it looks good except on one end it is a little off (about 1/3 inch off over a 4 ft span).
The complication with my tile installation is that I am putting in a heated floor using type that comes as a mat. I am also using penny round tiles. So if I install tile directly over the plywood (which has its own issues I realize) my fear is that I won't be able to get an even enough spread of thinset over the floor since I will be applying thinset over the webbing of the heated floor in one area and over the bare plywood in other areas. My understanding is that for penny rounds it is particularly important to have an even spread of thinset as the imperfections will be more obvious with such small tile.
So my other idea is to first apply self leveling compound to the plywood surface which contains the heated floor mat. I would apply this to the point where the heated floor is pretty much submerged (around 1/3 of an inch). After this cures I would apply thinset over that and tile. The self leveling compound is from Pro Level and comes with a primer for wood surfaces which I would apply first.
So my question is which approach makes the most sense for a DIYer with minimal experience tiling? Does anyone have experience using self leveling compound for such an application?
Many thanks for any advice...