I am after advice if there is anything that can be either painted or applied on top of a paving slab patio to make it waterproof. I have purchased a house that a previous owner laid concrete lintles across an old brick outbuilding when the roof was removed and then laid slabs on top to create a raised patio overlooking the city. Obviously water is penetrating the slabs and morter and running into the outbuilding rendering it useless as a store. Is there anything that may seal the slabs as i don't want the hassle of ripping it all off and was wandering if there is anything that would seal the patio from water penatration. Any ideas would be greatful.