Do metal buildings need lightning protection? If so, does it differ from wood or masonry structures?
A metal building is generally thin section metal. NFPA 780 states that metal bodies 3/16″ thick or thicker will take a direct lightning strike and conduct it to a grounding system. Metal buildings don’t normally qualify, only structural steel framing members (heavy steel columns and beams). Thin metal will melt through where the lightning attaches, so to protect the moisture seal of the roof, you need strike termination devices or lightning rods. The roofing isn’t a valid conductor, so you need cable conductors to the grounding system. A metal building or roof area is protected the same way you protect a non-metallic building, either wood or concrete.
