Do Metal Roofs Attract Lightning?

Do Metal Roofs Attract Lightning?

4 min read

An average lightning flash lasts about 30 microseconds, short enough not to give you time to escape from a building and seek refuge. Research on lightning protection shows that metal is the top-recommended roofing material for buildings located in lightning-prone zones.

A metal roof does not attract lightning but gives the strikes a low-resistance path. According to the Metal Construction Association, this can lessen the damage of a strike.

Are metal roofs dangerous during lightning storms?

Metal roofs are not dangerous during lightning. Essentially, buildings with such roofings can survive lightning strikes with lesser damage than similarly-sized structures relying on higher-resistance roofing materials.

This reaction is somewhat counter-intuitive, similar to the reasoning behind, “it is safer to be inside a metal-bodied car during lightning than when standing next to the vehicle.” To increase their lightning resistance ability, you can consider installing the roofs with a Lightning Protection System (LPS).

What happens when a metal roof is struck by lightning?

Metal roofs utilize aluminum rod protection systems. During lightning strikes, these systems will spread the energy from the lightning before directing it safely to the ground near the building. In other words, the aluminum rod offers a concentrated ‘hot point’ that can channel the energy safely while guarding the building against the chaotic consequences of lightning strikes.

On the other hand, metal roofs with multi-layered steel systems can resist the shock impact of striking lightning, keeping the structure safe and sound. That way, the strike gets a least-resistant path before settling on the ground. The lightning will neither enter the building structure nor attract the neighboring electrical wiring.

Are non-metal roofs safer?

Even though non-metal roofs seem like safer options for buildings, they do not offer reliable lightning protection. For instance, extreme lightning could cause fires. If your building is designed with a flammable, non-metal roofing material like wood shakes or asphalt shingles, it will instantly catch fire and burn the entire house.

These ordinary, non-metal materials do not provide lightning energy a clearer path to the ground. That means the lightning will ‘jump’ on the building’s floors and walls as it finds its way to the ground, posing lots of danger to the inhabitants.

And if electrical wiring systems neighbor your house, the lightning may use these wires as its path to the ground. The end is explosive power surges that could be extremely dangerous.

Does grounding a metal roof make it safer?

Electrical grounding provides lightning strikes an alternative route to reach the ground. Ideally, there are countless ways of grounding a building. Many residential properties attach bare copper wires to electrical boxes throughout the building structures. These grounding systems ensure that the lightning is safely dispersed.

Many homeowners think that the same principle applies to metal roofing systems. But is it essential to ground a metal roof in the name of increasing its protective levels during lightning?

The National Fire Protection Association and other reputable roofing contractors agree that metal roofs do not need grounding. And generally speaking, no building codes require homeowners to ground their metal roofs. However, these non-grounding rules apply if the homeowner strictly follows the basic building codes like using lightning arrestors and lightning rods.

Building owners could also consider using PVC piping and extending then from the house’s interior to its exterior. In other words, though grounding isn’t a must-do requirement, it does not pose any adverse effects on a structure.

Can metal roofs withstand strong weather?

Metal roofs also come in handy for use by people living in regions experiencing erratic weather – and this is not only limited to severe lightning strikes. Erratic weather also includes tornados, hurricanes, cyclones, blizzards, and dust storms.

As stated earlier, most traditional roofing structures could be highly flammable during such adverse weather conditions, posing significant risks to the building’s inhabitants. But this isn’t so for metal roofs – they offer enormous advantages!

For starters, metal roofs are sturdier and more super durable than traditional roofing materials. They can last for upwards of 40 years. They are designed to protect a structure from abnormal wind speeds of 140mph without breaking or rusting. Furthermore, the durability herein ensures that the fire will not spread to the property if the sparks of fire land on the roofs.

Their longevity does not diminish in these extreme weather conditions, and you will, therefore, rest assured that the roofs will protect your building for a prolonged time.

Dangers of lightning strikes on non-metal roofs

The actual danger of lightning to properties and human life during lightning depends significantly on three main factors. These factors include; does the building have occupants? Is the non-metal roofing structure combustible? Does the non-metal roofing structure contain combustible materials?

Electronic pieces of equipment are also sensitive to electrical discharges, increasing a building’s risk of experiencing significant lightning damage effects. That is because the electric charge from the striking lightning will always pass through electrically conductive materials without building up resistance.

The electronic equipment will also increase the threat of fire and explosion, increasing the threat to human life and properties.

How to protect your house against lightning

The two main ways extra-protective measures of making your house lightning resistant are laying a concrete foundation and adding a lightning rod on your metal roof. To install the lightning rod, connect copper poles to cables and let the cables run down the side of the building and into the ground.

This rod will draw away the negative charges of electricity from the structure to itself then transfers this energy to the copper cables so that the structure is well-protected from intense electricity surges.

It is worth noting that if lightning strikes a building, the structural integrity of this building and the occupants’ safety is significantly dependent on the building materials. Buildings with metal and steel materials are more likely to withstand the strikes than wood-framed structures.

Victoria Miller

I'm the founder of NTT. I live in Miami, Florida, and enjoy learning everything there is to know about tiny spaces.