At times retiling the bathroom is expensive, and hiring a professional can be pricey. Waterproofing over tiles is done to strengthen tile or grout against spills, erosion and leakage over time. These products are designed to specifically bond to ceramic and porcelain tile, and it will provide a barrier across the floor, both the tiles and the grout. It's very chemical resistant, very water-resistant and makes the tile much easier to keep clean.