We are building a new pool. The gap between the top of the tiles and the coping is between 0.25 to 0.75 inches. For example, for one side of the pool the gap slants such that the gap at the end of that side is almost half an inch higher than the gap at the beginning of that side. We are using premanufactured concrete coping.

I appreciate that it is impossible to have a completely consistent gap between the top of the tile and the coping, but how much variation is considered standard and acceptable?