Flooring Tile - ceramic tile grouting in shower

In 2000 we added a second floor to an existing ranch style home. Since we have experienced some settling, which is expected, but what bothers me is the cracking in the tiled shower. The grouting where the floor and wall tile meets cracks and starts to chip away. The same thing happens with the corner grouting approximately 6-8 inches from the floor. The first occurance the contractor fixed without question. The second time I regrouted myself. Removed existing grout, cleaned and applied the sanded grouting around the base and the non-sanded in the narrow corners. This will be the third time this has to be done. Is there something that can prevent further cracking? The shower underlayment is Durock, 6x8 wall tiles, the floor is a 2x2 tile. Any solution will greatly be appreciated and keep me out of the dog house.

Dennis

The grout will crack in those locations from now untill the end of time...especially when using concrete backer board. It is easily fixed using a flexible caulking in these areas...either silicone..or a siliconized latex caulk that is made for this situation...it will usually say "kithcen and Bath" on the tube of caulk.:rolleyes: