Hi - My husband and I just installed ceramic tiles using mortar last night. This morning I was cleaning up and preparing for the grout finish. I went around knocking on the tiles. Most are solid as a rock but a few have a hollow sound in the corner. Is this normal - I have a sneaking suspicion that they will crack a month from now. If this is a horrible mistake can we correct this in any way (maybe push the grout in there more aggresively?) Do I have to remove them?
Any help would be appreciated before we continue with the job.