Metal Roofing and Lightning Strikes: What to Know
A prevailing concern for home and business owners considering upgrading to a metal roof is the performance of metal during inclement weather, and lightning strikes in particular. Metal is a conductor, which is often taken to mean it attracts electric energy, much like the common misconceptions around lightning rods. In fact, the conductive nature of metal construction products is a benefit during a lightning event.
The probability of being struck has little to do with the building materials used; instead, it is determined by several external factors, such as
- Topography
- Size & height of structure
- Relative location to other structures
Lightning is fairly indiscriminate, seeking the least path of resistance. It’s attracted to the highest structure in the area, regardless of building elements. “Research shows that the material used in roof construction does not influence the risk of a lightning strike,” says Karl Hielscher, the Metal Construction Association’s executive director. “In fact, the presence of a metal roof really shouldn’t statistically increase or decrease the chances of a lightning strike.”
Other popular construction components, such as wood, cement, or composites, are poor conductors, resulting in increased electrical resistance. This causes heat, leading to potential damage. Fire is the most destructive element of a strike, as most roofing materials are liable to catch flame. Because metal roofing is a conductive and noncombustible material, allowing the current to safely disperse and discharge, reducing the risks associated with a lightning strike.
Despite its superior performance in lightning events, metal roofing is not a failsafe solution. For those at higher risk—the tallest building, or the sole structure on a high topographical range, for example—implementing other safety measures may be beneficial. The only way to guarantee defense against lightning damage is by installing a properly designed lightning protection system.