Each has its purposes and advantages. An overlay is certainly a cheaper alternative, but often will not last as long. When asphalt fails, it is usually the base below the asphalt that has failed first. If the asphalt is not removed, we don’t have the opportunity to correct the base failure problem. Overlays are often susceptible to so-called reflection cracking, where the cracks in the underlying pavement will “reflect” through and begin to show in the top layer.