We moved into this home about 25 years ago. It is a "Mid-century modern" with green, gray, and red slate tiles in the entry. When we moved in, some of the tile were loose and we had a tile-guy take them up and put them back down. In about 5 years, the same thing...take up and re-install. We have had this done 4 times and need to do it again. These are reputable tile-guys -- premier floor covering/tile people in the area. One thing...they always use mortar to set the tiles. I asked about using mastic instead of mortar, but they always say "no." I have installed lots of ceramic tile over the years and used mastic & grout. None have ever come up.
What are my guys doing wrong?
