We have a screened porch with a porcelain tile floor, and some of the grout has begun to crack. In order to regrout, do I have to remove ALL the grout from the entire floor, or can I just remove the sections that are crumbling?

Thanks for the help!

If you do just part, you run the risk of a two tone floor, part new bright and clean and some old and dirty looking. You did not say what color, but comes into play.

Do a small amount and see how you like the result and decide from there.

Good luck Roger