I have a concrete slab patio (roughly 25′ x 10′) that is in pretty good shape. My wife and I have thought about covering it with stone or porcelain tile. The problem is that the concrete pad slopes toward the house. (It looks like the previous owner poured the pad himself.) The pad itself doesn’t appear to be sinking. Can I “fix” the slope of the pad by adjusting the thickness of the mortar when I lay the stone? At most I think we’re dealing with about a half-inch difference between the low and high spots. Any thoughts would be great.

Thanks.