Grout Shrinks or Cracks

[penahill]

I am very interested in Avaire and considering putting it my bathroom. I have 2 questions about the grout. The first question is Does the grout shrink over a period of time? When I say shrink I mean does it pull away from the tile creating a seam that water & dirt can go into. The second question is Seeing this is a floating floor and you need to leave a 1/4 in gap around the edges except tubs where you caulk, How do you prevent water from getting under the tiles? An example would be the toilet overflowed.

Thanks

Paul