Can I use tile adhesive over old mortar to fix loose tiles?
I did my floor tile project a year ago. I have 2x10 floor joists at 16” on center spanning 12’. My subfloor is two layers of plywood, ¾” on bottom and 5/8” on top. I mortared and screwed down ¼” cement board as a base for my tile. I used a 1/2" square notch trowel with modified thin set to set the tiles. Based on the tiles I pulled up, my mortar coverage was only about 60% to 80%.
I have a few of my 18" porcelain tiles that are loose near where I rolled by refrigerator around a few times. The grout did not crack at all. I only noticed a few were loose by occasionally hearing a slight noise when I stepped on them.
The think the issue is that my coverage wasn’t good enough. Also I did not back butter them which didn't help any.
Will it work to just spread a thin layer of tile adhesive using a thin triangular notched (about 1/8" triangular notches) shaped floor adhesive trowel right over the old mortar? I was also kicking around first spreading mortar over the areas without coverage to have a totally flat and solid base and let dry. Then apply the adhesive to have a 100% solid flat base to work on.
Alternatively, I could just chisel off the old mortar and try again with better coverage.
Also, any tips on how to keep the fridge from hurting the tile? I was thinking of rolling the fridge around on 3" wide by 1/8" thick steel plates to help distribute the load better.