We loved our concrete coping. It was really perfect. Ask your builder if he does this alot and if he is good at it. Although that may seem like a silly question to ask a builder, the concrete coping is difficult to do. They use a styfoam form that the concrete flows into and makes the ledge. The builder cannot "see" into the form, so if it is not totally full and even, then your coping is uneven or worse. I think that is why most builders are using pavers as a alt to rim lock coping.