Floor tiling, grouting in bathrrom and toilet????

[Tech_Man]

Hello

I have recently tiled my bathroom and toilet with ceramic tiles. As mentioned i made sure the floor was level and put ply wood down etc.

The problem i am having is that my grouting has cracked on some tiles.

I was wondering whats the best stuff to gout the tiles with and how do i prevent this?

 

[Mudster]

BAL Superflex or BAL wide joint with GT1 admix.

Or any grout described as flexible and suitable for small amounts of vibration.