 somewhat of a sealer but it's a breathable sealer and that's really the key if you're in you know climates where you can have hot and cold you want something to breathe you want to exhaust that moisture from underneath that slab out but you want to minimize the amount of moisture that can come in so there's still some transfer but it's minimized it'll stay longer pressure washers nothing wrong with the pressure washer love to use my pressure washer