I remodeling my 3rd floor kitchen in a 40 year old home and preparing it for ceramic tile install. I am in the process of removing the existing vinyl flooring and subfloor since it dips in some areas and had slight water damage in others. The existing floor has 3 layers of subflooring, 3/4 inch planks on top of the joists, 1/2 inch particle board and a 5/8 inch plywood on top of it all (all fastened with nails) where vinyl tile was once installed. I have attached a pic. I planned on removing the 1st 2 layers of the floor down to the planks and replacing them with 1 layer 5/8 inch T&G plywood and installing ceramic tile on top of that. I will probably be installing Ditra as well.
Are the existing planks and the 5/8 inch plywood sufficient for a ceramic tile install ?
Should I put down 2 layers of plywood over the existing planks ? A 5/8 inch layer and a 1/2 inch layer ?
How would I secure it to planks and joists ? Should it be glued to the planks and screwed down though the joists ?