Shower floor tile

I have a interesting problem that a couple of tile people have looked at. Shower is five years old, in that time joints around the wall have separated from humidity and house movement. Repairs have been made to the grout lines during this time. It is now time to sell house and wanted to get all things fixed first. Hired someone to fix all grout problems in shower. Job came out great except for some lines in floor that will not lighten up (dry). After a couple of weeks he came back and cut out the grout that would not lighten (dry) and left it for a couple of weeks so mud bed could dry if wet and then re-grouted. Same problem, same spots (grout lines). Waited a month to see if it would dry, didn't. Re-grouted dark spots, same problem, its been three months still not right. Need some help

Sounds to me like there was not a proper pre slope under the pan there for you have water sitting and it will take a very long time to dry 6 months to a year. As for the grout cracking along perimeter dry pack was not packed properly would be my guess.

Sounds to me like there was not a proper pre slope under the pan there for you have water sitting and it will take a very long time to dry 6 months to a year. As for the grout cracking along perimeter dry pack was not packed properly would be my guess.

Agreed!

Concrete shower receptors require a preslope under the pan liner so as to evacuate any and all water. If there is no preslope the pan liner sitting flat on the subfloor could hold water for a very long time, maybe years.

You might try to remove all the grout (one-more-time) and use an epoxy grout next time. Hopefully the grout will "set" before the moisture can have any effect on it.

The only other option is to take out the receptor and start over doing it properly this time.