What is Liquid Rubber Foundation Sealant used for? Liquid Rubber Foundation Sealant is used for waterproofing foundation, interior basements, showers and away from UV. Use Liquid Rubber Waterproof Sealant for UV environments. Related articles Can this product be used to waterproof shower walls and base? Can it be tiled over? How do I cover gaps and cracks? Comments 0 comments Please sign in to leave a comment.