I have 12" sq. tiles in my bathrooms & some of them have separated from the mortar on the plywood sub-floor. I haven't pulled any tiles yet, so I'm not sure of the actual cause, or of the construction, but I believe the mortar has dried over the past 20+ years and lost their adhesion. As I step on specific tiles there is a loud popping noise leading me to think my weight is pinching the tile on their side edges. In any event, I'm considering re-mortaring these tiles, but am concerned that as I try to remove the individual tiles that adjacent ones may loosen as well leading me to have to chase more loosened tiles to lift all the loose ones out. Also, is it reasonable to expect that the old mortar will scrape off cleanly to allow the new mortar to adhere properly?
I'm a long time DIYer, but if this has the ear marks of a problem type of project, perhaps I should hire someone to do this.
I'd appreciate your thoughts.