Abstract: Plastic extender rings for manholes are produced and are seated on the top ring of a manhole by the use of caulking or other adhesive material. The manhole cover, which is elevated by the plastic ring or rings from the old pavement level to a new pavement level, renders the manhole cover less noisy to traffic and seated more evenly. Recessed or notched portions of the rings receive the asphalt to arrest rotational and upward movement of the rings. Composite adapter rings are provided to adapt an off size manhole top rings, to a standard size manhole cover. Plastics are employed which will not melt at the application temperature of asphalt but will soften somewhat to conform better to the contour of the manhole cover and/or underlying manhole top ring.

Abstract: Plastic extender rings for manholes are produced by molding as a unitary member or extrusion or in molded segments and are seated by the use of caulking or other adhesive material. The manhole cover, which is elevated by the plastic ring from the old pavement level to a new pavement level, is rendered more silent to traffic and is seated more evenly. Plastics are employed which will not melt at the application temperature of asphalt but will soften somewhat to conform better to the contour of the manhole cover and/or underlying manhole top ring. Plastic fillers may be employed in the product to regulate plasticity and increase resistance to deterioration from the elements and from ultraviolet.