An overlay is used when the surface shows significant deterioration but is still suitable as a base and allows proper flow of water.  We can determine what areas have to be milled to allow for smooth transitions between the overlay and the surrounding asphalt or concrete.  A layer of tack is sprayed to glue the new surface to the existing asphalt; followed by the asphalt overlay.  Fabric is sometimes used to help reduce the chance of cracks coming back through the new asphalt surface.