Homeowners who own a metal roof, or are considering switching to one, often ask us about whether or not they need to protect their home from lightning strikes by grounding the roof. In today’s post, the local roofers at Winfield Builders share insight on grounding metal roofs.
Lighting and Metal Roofing
First, let’s examine how lightning would behave. A common assumption is that metal roofs attract lightning because metal naturally conducts electricity. Here’s a quick fact: what attracts lighting is the grounded object area that offers the least electrical resistance, which, in most cases, happens to be the tallest structure in the area. It could be a lone tree on an open field, a church spire in a busy district, or a lightning rod in a residential area.
If your home happens to be the tallest structure in your area, you might be surprised to know that you’re safer under a metal roof during a lightning storm. A metal roof’s natural conductivity can disperse an electrical charge more efficiently, which makes it less vulnerable to damage caused by lightning. Metal roofs and gutters are typically installed on non-conductive materials like wood, and therefore don’t pose the risk of electrocution to people staying indoors.
Conditions That May Require Grounding
Generally, metal roofing systems do not require grounding, nor is it required by international building codes. However it may be a requirement in local building codes if one or more of the following conditions are met:
Topography — Properties with significant variations in its topography, such as hills and flatlands, are typically at increased risk of lightning strikes.
Building height — Tall structures are typically at greater risk of lightning strikes.
Proximity to a tall structure — If a house or building is placed too close to a tall structure—natural or man-made—it is at less risk of getting hit by lightning. However, grounding the roof can be a safety precaution in case of secondary strikes.
Frequent lightning storms — Homes located in areas prone to thunderstorms may be required to ground their metal roofs.
Winfield Builders is your leading provider of metal roofs and replacement windows. Give us a call at (410) 401-5045. You can also fill out our contact form to schedule an appointment. We serve customers in Silver Spring, Rockville, and Annapolis, MD.