Choosing the correct sub floor

GP's House

I am in the process of rehapping a home my gandfater built. He was a master capter his entire life and the home is 2 stories solid poured concrete roof since it's on the ocean in hurricane alley. The 2nd floor is supporeted by 2x10 joyce which we just replaced due to termite damage. So now we have all new PT joyces and 3/4 pt ply wood down. Currently there are no walls, just wide open space. since we are going to be putting up new walls and the plan is to tile, I would like to know what type of sub floor to use over the PT plywood?

Also should we put the sub floor down all the way across the floor before and build the walls ontop of the sub floor?

we are planning to go with a zero grout line tile to avoid cracking as much a poossbile and probably a 12 to 14 ich tile. any thoughts

R&D Tile

No PT plywood should be used if tiling, it will warp and shrink and cause issues in the future, hopefully the joists won't, no guarantee there either.

Use Ext. Grade AC or BC ply for the subfloor, 3/4" then a layer of 1/2" or better, then a CBU or membrane before tiling.

You need a grout joint, what size depends on the tile, but you need one, never butt tile.

Bud Cline

You could also use some knowledge in other areas as well. You could go to your local-government Building Inspection Office and get some direction from them. Sounds as if you need a permit anyway. Those guys can be very helpful.