My bathroom has only been 4 months but grout has already cracked around joints between bath tub and wall in one bath room, shower wall and floor for master bath, and joint between shower walls. I at first suspected it was a bad case of foundation shifting (Dallas had bad rain around April and May) but then I realized it might have been because of the shitty jobs by contractor. Grout was used is unsanded grout, they didn't even use caulks for the joints area. I used subway tile for the shower and hexagon ceramic mosaic tiles for master bathroom floor, nothing really fancy. I am having someone else to come and fix the damage. Can someone please advise on which type of grout should I use this time? I m looking at Mapei flexcolor or opticolor. I want to prevent cracking from happening again in the future. I appreciate all the responses.