Hi Bob, we were wondering if you could shed some light on our ceramic floor tile problem. We live in Toronto, Canada, our building codes may be different than yours? We purchased a new home from a builder, it is now one year old, about six months ago we discovered that when walking on certain areas the floor would make crunching eggshell type of a noise. Then we discovered that the grouting in these areas has cracked and is flaking. We have contacted the builder, all they have done is re-grout the entire area. This problem has since re-occurred, the builder has told us that this is due to settling and they would have another look at it. There is 3/4 inch plywood with scratch coat cement, with wire mesh under the floor tile to the best of our knowledge. We are trying to get your professional opinion on what may be the problem before we call the builder and have him pull the wool over our eyes. P.S. we forgot to mention that some tiles are actually loose, when you press on the corners with your thumb you can see movement, the tiles are 13x13, the area affected is the main floor hallway and kitchen. We also have ceramic tile in three other bathrooms with smaller tile and same sub floor, we have had no problems there.