Identification

• Copper, the traditional metal used for roofing, has largely been replaced by less expensive and more durable steel and aluminum. Copper, however, is still used for flashing. The basic steel standing seam roof is strengthened by seams between panels, folded and crimped to form an exceptionally weather-proof roof. Metal shingles are molded, a process that adds strength to each piece. Shingles take the form of Spanish tile, cedar shakes or plain asphalt shingles and are coated with vinyl, rubber or ground stone in a wide range of colors. Coated shingles are lightweight, fireproof and wind resistant; many carry a warrantee for a lifetime of 50 years or more.
  
  

Hail

• Most U.S. areas experience occasional hail events, but four states: Kansas, Nebraska, Oklahoma and Texas, take the brunt of the damage. Texans alone average 500 hailstorms per year. Colorado has the most storms with large hail that measure more than 1.5 inches, but State Farm Insurance quotes Texas officials estimate that 40 percent of homeowner claims include hail damage. Texas, not surprisingly, sponsors extensive research into hailstorms at Texas Tech University. The state offers insurance discounts for hail resistant roofing and lists two dozen makers of compliant metal roofing, including shingles, shakes and tiles.
  
  

Rating Facts

• Standards for roofing applicable to metal shingles were developed by Underwriters Laboratories (UL) with State Farm’s Institute for Business and Home Safety (IBHS) in 1996 that propelled metal balls at roofing to establish ratings known as UL 2218. UL’s ratings range from 4, in which roofing sustained two hits in the same place by a 2-inch steel ball to 1, in which a 1.25-inch ball is the largest double hit that the material resists successfully. Research continues on the effects of frozen water impacts at IBHS. Metal shingles often rate as Class 3 or 4 impact-resistant roofing, meaning that they will survive hailstorms equivalent to impacts of 1.75 or 2 inch steel balls.
  
  

Other Considerations

• Metal shingles 26 gauge or thicker qualify as Class 4 roofing and shingles have an additional advantage if they are molded into shapes, which makes them stiffer and stronger than seamed metal panels. Flexible coatings also help cushion the blow. Hail does the most damage when it hits flat roofs at a 90-degree angle, but slides down roofs with steeper pitches over 29 degrees. Blueprint for Safety, a public-private alliance under the aegis of the Federal Alliance for Safe Homes, recommends laying new roofs over 5/8 inch plywood sheathing for maximum support.