The 30-year old house we are renovating has a big concrete balcony, part of which is actually the roof of part of the garage. The concrete has never been coated, and the surface has a crazed appearance. In the last heavy downpour I noticed water dripping from the ceiling in the garage. The water was coming through a crack visible on the underside but not on the top.
I want to seal the concrete, not so much because of the leak, but because I'm concerned about the effect of the water getting into it. Apparently the first step is to etch the surface. My question: what is the best coating for this purpose?