We purchased a 5-year old home with walk-in marble tile shower that has
developed small cracks between the tile walls and tile floor and also
vertically between the side and back walls. The areas were originally
grouted rather than caulked but I've been advised they should be
caulked. Do I need to remove the existing grout first? Also, any advice
on what's best to clean the marble around the joint before caulking?