Granite Floor Tile Help
I'm installing granite floor tiles (3/8" x 12" x 12") in my bathroom.
My bathroom is 5 ft wide x ~10 ft long. My tub is against the back wall, so I'll only tile up to it (5 ft wide x 7.5 ft long).
My floor joists are 2" x 8" and 16" On Center. However, under the bathroom it goes, 16 OC then 8 or 9 OC then 16 OC then 16 OC (so four joists under the bathroom floor).
The main subfloor directly on the joists is 1/2" thick. I'm stuck on the correct underlayment and subfloor thickness and types required.
I have read that you need a strong floor to support granite tiles as its predominately a heavier tile. I was thinking of putting 1/4" ply on top of the 1/2" subfloor, followed by a 1/4" cement board for tile, totaling 1" support under the tiles.
Will this work for support? I also want to make sure my tile doesn't crack due to the house shifting also, and I don't know if this allows for it.
My other idea was 1/4" ply with a 3/8" ditra (D-W-S-10), however the ditra manual says that the 3/4" floor requirements include tongue and groove, and I'm not sure anyone in this city has 3/8" ditra.
Please keep in mind with all suggestions that we will be installing 3/4" solid hardwood in the hallway and living area outside the bathroom (which also has the 1/2" subfloor). I want it to be as close as possible, so unless I put plywood ontop of the subfloor in the hallway, I have to be around 3/4" height in the bathroom.
Please provide some suggestions.