How do I repair the cracks in the grout of the mosaic tile in a shower stall, circa 1960? Water has seeped through the ceiling dowstairs under this bathroom. The existing grout seems much harder than the grout around the 4x4 wall tiles. Is it a different type grout? Shouldn't there be a pan under the mosaic floor portion of this stall? Is there such thing as a rubber sealer to cover the entire mosaic tile to ensure waterproofing? Thank you in advance.

debbie beard

If you are talking about the floor of the shower stall you have some larger issues. A good shower pan is water tight without even having tiles or grout. The tiles and grout form a surface to create wearibility and good looks. If the grout fails you should not have a leak down stairs. In your case the pan has also failed and should be repaired or replaced. Regrout is a band aid but might last for years. You can buy grout removal tools that are hand tools or for a rotary Dremel motor.