Subfloor question for tiling a bathroom floor with heat mat under the tiles
My bathroom's subfloor is an old tongue and groove sub-floor 7/8" thick. It seems to be in "OK" condition but I am little bit concerned of my plan.
Here are the layers:
1. Current tongue and groove 7/8" thick subfloor
2. A layer of modified thinset cement based mortar (using 1/4" notch trowel)
3. 1/4" Wedi building panel
4. SunTouch heat mat
5. at least 1/4" modified thinset cement based mortar (or maybe SLC) to cover the mats (let it dry)
6. 1/4" modified thinset cement based mortar
7. 3/8" ceramic tiles 12"x24"
Do you think I should strengthen the subfloor? The joists are spaced 16 OC.