Lightning Strikes on Commercial Roofs – Risks, Damage, and Prevention

Avoid revenue loss, severe structural damage, and destructive power surges when lightning strikes your commercial building. Understanding the power lightning carries and how to divert it will help prevent catastrophic lightning damage to your building and business.

New Image Roofing Atlanta gathered information about how lightning strikes wreak havoc on electrical systems, appliances, and structural elements and what you can do to mitigate them.

What Attracts Lightning to Commercial Buildings?

Lightning naturally seeks the shortest and easiest path to the ground. It is attracted to:

Tall Structures – Taller buildings and structures become prime targets for lightning strikes. The higher a building rises above its surroundings, the greater the chance lightning will strike it. This is particularly true for skyscrapers, factories, and commercial complexes.

Metallic Objects – Lightning also seeks conductive materials like metals. Many commercial buildings use metal roofs, have rooftop equipment, or feature metal structures that make them more attractive to lightning.

Rooftop Equipment – Antennas, HVAC units, satellite dishes, and other equipment on commercial roofs provide pathways for lightning to reach the building’s electrical systems.

These objects increase the likelihood of a direct hit during a storm.

Water or Moisture – Wet surfaces act as efficient conductors for electricity. A wet commercial roof, especially metal, can amplify the chances of a lightning strike and increase the damage potential.

Visit FEMA’s National Lightning Risk Index to see your area’s relative risk for lightning strikes HERE.

Energy in a Lightning Strike

Lightning carries immense energy, capable of causing catastrophic damage. The average lightning bolt can have between 1 billion and 10 billion volts of electricity, with current ranging from 30,000 to 300,000 amperes.

The energy released during a lightning strike happens in microseconds, making it incredibly destructive. The heat and force can set fire to combustible materials. At the same time, the sheer electrical energy can cause massive surges in electrical systems.

Note: A lightning strike can exceed 50,000°F (five times hotter than the sun’s surface).

Potential Damage to Commercial Buildings and Electronics

A lightning strike on a commercial roof can cause multiple damage types, ranging from minor structural issues to significant system failures. These are among the most common damages:

Fire – The extreme temperatures generated by a lightning strike can ignite roofing materials, insulation, or even the building’s framing. Commercial buildings with combustible roofing material or stored flammable materials are particularly vulnerable to lightning fires.

Roof Damage – A lightning strike can blow holes in a roof, crack tiles, damage membranes, or displace entire sections of roofing material. These openings allow water to enter the building, leading to leaks and further structural damage.

Electrical Surges – When lightning strikes a commercial building, the electrical surge that follows can:

• Overload wiring systems
• Destroy electronics
• Seize HVAC systems
• Shut down security systems
• Render essential building infrastructure (including elevators) unusable

Computers, servers, and other equipment sensitive to power surges are especially at risk.

Structural Damage – A lightning strike can disrupt structural elements. A lightning strike can crack walls, damage windows, and shift a building’s foundation. These damages pose severe risks to the building’s safety and stability.

Who to Call After a Lightning Strike

After a lightning strike, taking immediate action to assess the damage and ensure the building’s occupant’s safety is crucial. Here’s who you should contact:

Emergency Services – If you detect any fire or gas leaks following a lightning strike (call emergency services immediately). Firefighters can quickly address visible fires, while police can help secure the area if needed.

Electrician – A licensed electrician should assess the electrical systems for damage. Electrical surges from lightning can cause hidden damage to wiring, outlets, and equipment that may not be immediately visible but can pose a risk of fires or system failures later on.

Roofing Contractor – A ROOFING PROFESSIONAL needs to inspect the roof for punctures, cracks, or any damage to the roofing materials. Even small holes can lead to significant water damage over time if not repaired promptly.

HVAC Technician – Many commercial buildings have HVAC units installed on the roof, which are highly vulnerable during a lightning strike. A technician should inspect HVAC systems to ensure they function without severe electrical damage.

Insurance Company – Contact your insurance provider to report the damage and initiate a claim. Document all visible damage, including photographs and written descriptions, as part of the claim process.

Watch this video for more information about insurance policies and how deductibles work.

Preventing Lightning Damage to Commercial Buildings

While you cannot prevent lightning strikes, you can take measures to reduce damage risks and protect your building. Here are some steps building owners can take:

Install a Lightning Protection System (LPS) – A lightning protection system consists of lightning rods, conductor cables, and ground rods that work together to safely direct the energy from a lightning strike away from the building and into the ground. LPS systems are essential for taller buildings or in areas prone to thunderstorms.

Lightning Rods – These rods, installed on the roof or other high points, attract and minimize lightning strikes.

Conductors – These cables carry the electrical charge from the rod down to the ground without letting it pass through the building.

Grounding System – Ground rods safely dissipate the energy into the ground, preventing it from entering the building’s systems.

Use Surge Protectors – Commercial buildings should have surge protection devices (SPDs) in their electrical systems. These devices protect against voltage spikes caused by lightning strikes and prevent damage to sensitive electronics.

Whole-building surge protectors work by diverting excess voltage away from electrical systems, ensuring appliances, computers, and other devices do not suffer damage.

Maintain a Safe Distance Between Trees and Buildings – Trees near commercial buildings can act as lightning attractors. If a lightning strike hits a tree, it may cause large branches to fall on the roof, leading to additional damage. Regular tree trimming and ensuring no large trees are close to the building will help reduce this risk.

Install Non-Conductive Roofing Materials – Buildings with metal roofing systems are more attractive to lightning strikes due to metal’s conductive nature. Consider installing non-metallic roofing materials that offer fire resistance, reducing the likelihood of fires after a strike.

HVAC and Rooftop Equipment Shielding – Ensure rooftop equipment like HVAC systems, antennas, and satellite dishes are properly shielded and grounded to protect them from lightning damage. Adding surge protectors for these systems can further prevent damage.

Lightning and Commercial Buildings

In this article, you discovered how lightning strikes are attracted to commercial buildings, the damage they cause, how to divert them, and what to do after one.

Knowing how to divert or prevent commercial building lightning strikes can help you avoid severe structural and electrical damage.

Ignoring the need for lightning protection systems and using non-conductive material in your building’s construction can lead to catastrophic damage to your structure and electronic systems/equipment and result in indefinite business closure.

Sources:
noaa.gov/jetstream/lightning/lightning-safety
nvlpubs.nist.gov/nistpubs/Legacy/IR/nistir89-4113.pdf