Waterproofing bathroom walls and floors is important to prevent damage from water and moisture. This can be done by applying a cross hatched waterproofing membrane or coating to the walls and floors and ensuring that all areas that may come into contact with water, such as around shower heads, bathtubs and sinks, are properly sealed. Additionally, proper ventilation in the bathroom can help to prevent the buildup of moisture, which can lead to mold and mildew growth.