Metal Roofing FAQs

A well-installed metal roof commonly lasts 40 to 70 years, compared with about 20 to 25 years for architectural shingles in the Memphis climate. An industry-sponsored study projects unpainted aluminum-zinc coated steel standing seam roofs can last 60 years or more with annual maintenance.

A metal roof typically costs two to six times as much as an architectural shingle roof on the same home. Where your roof falls in that range depends on the panel type, the metal and finish, roof size and pitch, and how many valleys, chimneys, and other details need custom flashing.

Large hail can dent a metal roof, but dents usually don’t mean the roof will leak. Many metal panels carry a UL 2218 Class 4 impact rating, the highest level, which tests whether the panel cracks or opens up, not whether it dents. Thicker panels and textured or ribbed profiles show dents less.

Standing seam panels are joined by raised seams and fastened with hidden clips or seams, so no screws go through the face of the panel. Exposed-fastener panels are screwed through the face with rubber-washered screws. Standing seam costs more, needs less maintenance, and works on lower slopes. Exposed fastener costs less but needs periodic screw checks.

Sometimes. Building codes generally allow a new roof over one existing layer of shingles, but not over two or more layers. Even when it’s allowed, we usually recommend tearing the shingles off so the decking can be inspected and repaired, and the metal can be installed over a clean, flat surface.

A metal roof with a light-colored or reflective “cool” finish can keep the roof much cooler in summer sun, which can lower air conditioning demand. The U.S. Department of Energy says a reflective roof can stay more than 50°F cooler than a conventional roof. Dark or unpainted metal doesn’t get the same benefit.