I have about 2000 sq. ft. of 12" Travertine tile in my home. Every
two or three years I have to replace at least 20 tiles because of
cracking. I am in California and as many of you know, we get quite a
few minor earthquakes yearly. We also get a major one every few years
which does not help the problem.

Originally, the tile was laid directly over the concrete slab with
thinset. When replacing the tiles I have been using a thin layer of
mastic, then a layer of roofing paper (black "tar" paper) and then
another thin layer of mastic. I had hoped that this would insulate the
Travertine from the slab. It does not … some of the tiles continue to
crack but at a slower rate.

I am getting ready to replace another 20 tiles. Does anyone have any
ideas as to how to secure the tiles in place yet allow some
flexibility to prevent cracking? I suspect that I might end up with
some cracking of the grout but I would rather replace the grout in
these areas than replace the entire tile.

Norm