I am currently having approx 750 sqft of my home tiled with walnut, honed, chipped and unfilled travertine. It is being installed in a Versailles pattern. After the first day, I have noticed several hollow spots by tapping on each of the tiles. I would say that about half of what has been installed is like this. they are using They are using Mapei Keraflor and I believe they were using something different in the kitchen. Also, the tiles are being butted together in several places. The manufacturer recommends a 1/4 inch grout line. They have also installed the tiles over the existing vinyl sheeting in the kitchen. I was most concerned about the hollow sound as I’ve heard that natural stone must have 100% adhesion or it will fail. This was my original concern until reading several posts on the web including this one. The tile installation company is reputable from what i have gathered and has been around for a while. Do I need to stop everything? What should they be doing differently and will the tile already installed need to come up. I am starting to think that I have made a COSTLY mistake. What do you think? – Michael
There are several issues here. First, installing over vinyl in the kitchen is a practice when there is a crawl space under the house.
The vinyl is a good moisture barrier. However, cement board must be screw in over the vinyl to provide adequate tile adhesion. It might sound solid today, but it will not in a year from now as the house expands and contracts. Don’t cross your fingers. Get a warranty for adhesion of the tile at this location.
Secondly, the tile you described should be installed with a 1/4″ grout joint and sanded grout. Perhaps a little tighter if that is your preference, but never butt tight. That is not the correct look for this tile or this pattern. You can find many photos by searching google images, “Versailles pattern stone flooring”. Also, be sure to apply a good sealer to the grout and tile when done or this will be maintenance nightmare.
Lastly, the hollow sounding is usually caused by the installer not using a deep enough trowel. Personally, I recommend a 3/8″ or 1/2″ square notch trowel. Anything less will not provide enough thinset under the stone tile which is required to compensate for irregularity in the subfloor. Also, each corner of the stone tile should be ‘back-buttered’ with a glob of thinset because this is the weakest spot and the most common hollow sounding locations. It is best to flat trowel thinset over the back of the entire stone tile before setting in place. If you floor sounds hollow now, you grout will crack in the near future.
Sorry for the bad news and my very best wishes to you.