Waterproofing, by definition, means to stop and prevent the intrusion of water. When looking for a waterproofing sealer, make sure the sealer can be used where hydrostatic pressure is present. Hydrostatic pressure is the force that pushes water through concrete. Most sealers can’t be used where hydrostatic pressure is present which means if you really want to use the sealer you’ve chosen, you must first apply a sealer that can stop hydrostatic pressure.
Waterproof coatings do just that, they coat the concrete with a surface film and prevent liquids and other things from getting to or at the surface of the concrete. While waterproof coatings are strong and will protect the surface, they can’t and don’t protect the concrete below the surface. Once water becomes present within or below the concrete, the waterproof coating will start to bubble, peel, or flake. For the best protection you want to apply a penetrating concrete sealer then apply a coating to the surface.
Popular concrete sealers: Foundation Armor