How High-Performance Roofing Can Prepare Your Building for Extreme Weather

Extreme thunderstorms. High winds. Tornadoes. Hurricanes. Very Severe Hail.

These are some of the weather threats impacting the built environment. Homes, buildings, stores, and other structures are designed to protect human life and property, though at times, Mother Nature can still win.

The long-term effects of severe weather damage to a commercial property can be catastrophic for operational security and business continuity. Internal operations may be disrupted or halted. Downtime can be extremely costly due to lost production, product spoilage, or water damage to critical infrastructure. Prolonged flooding can lead to mold growth, contamination, and indoor air quality issues, and even potential electrical hazards. Together, these consequences don’t just threaten the business. They can also jeopardize the safety of workers in the facility.

Your roof represents a critical opportunity to minimize risk from these types of weather events. Roof systems can experience major damage from gale-force winds, torrential downpours, and severe hail. Among many common commercial roof systems on the market today, some provide elevated performance characteristics that enable them to resist storm damage more effectively than others.

This article will explore common types and causes of roof failure during extreme weather; the importance of roof preparedness and proactive maintenance with respect to extreme weather; and key performance characteristics of high-quality roof systems that help best protect your business when a storm strikes.

Common Points of Failure for Commercial Roofs

Tornado season in the United States extends from May into early June throughout the southern Great Plains, which includes states like Texas, Oklahoma, and Kansas, and serves as a good example of the kinds of threats a commercial roof can face during critical weather periods of the calendar year.

Your building may not face a direct impact from being in a tornado’s path, but it may face other peripheral threats. High winds associated with tornado conditions can result in flying debris that has the potential to tear or puncture your roof membrane. Tree branches, fencing, vinyl and metal siding, sheet metal, scaffolding, vehicle parts and more can all be picked up by tornado winds and, if they land on your roof, can cause major damage. Consequences may include roof failure and significant leaks.

Elsewhere, the wind itself poses another severe threat to commercial roofs. Windward perimeters and corners are typically the first areas to fail under high-wind loads. High winds can stress edge details, especially if they were improperly installed or have deteriorated over time. This can lead to membrane peeling and, in severe cases, total roof failure. Sections of the roof where equipment penetrates the membrane are susceptible to the same type of damage. Your vent systems, exhaust fans, HVAC equipment, and any other units connected to interior operations are all met by edges of the roof membrane.

Hail is another extreme to consider, as associated damage may lead to immediate punctures and water intrusion. The damage may also be more subtle, with less severe strikes contributing to an overall weakened system that may fail prematurely. Specifically, Very Severe Hail (VSH), classified as hailstones that exceed 2 inches in diameter, is a potential threat in some parts of the country and can cause significant puncture damage to roof membranes. To help mitigate some of these threats, Underwriters Laboratories (UL) classifies roofing material impact resistance from Class 1 (weakest) to Class 4 (strongest) based on resistance to steel ball drops simulating hail. Class 4 is the highest rating, indicating the ability to withstand 2-inch hail.

Following a storm, damage can be classified as cosmetic or functional. Cosmetic damage, such as surface dents or minor scuffing, may not compromise waterproofing and is often excluded from insurance coverage. Functional damage, including membrane punctures, cracked flashings, open seams or insulation saturation, can lead to water intrusion and typically requires immediate repair or replacement.

Maintenance Best Practices for Mitigating Storm Damage

No matter the composition of your roof membrane (which we will explore in the next section), proactive maintenance practices are essential to mitigate risk during severe weather events.

It’s important to regularly inspect the condition of your roof. Typically, these inspections can be performed in the spring and fall. Spring is an optimal time to ensure your roof has successfully withstood the winter months and is in good condition for the summer months that are more typically associated with storms, high winds, and other threatening conditions.

What to look for? First, an inspection gives you the opportunity to clear any accumulated debris that may already be on your roof system. Removing such items is an easy way to mitigate their potential to cause damage in high-wind conditions.

Second, your inspection will reveal any minor or major issues that may become larger problems during a weather event. For example: inspect the perimeter for signs of damaged, loose, rusted, or missing flashing that may contribute to edge failure in the event of severe wind. Other issues you might uncover include improper fastener installation or adhesion failure, loose or disconnected metal edge, open seams, or areas that can be easily addressed with simple repairs.

Depending on the age of your roof system, you may uncover larger issues that require more significant repair or replacement, including severe punctures or penetrations and excessive saturation. This is especially critical ahead of a storm season, where vulnerabilities are more easily exploited, and can cause real damage to your business.

Comparing Performance of Common Roof Systems

Among the available roof membranes in today’s market, options vary when it comes to how well they withstand severe weather conditions.

Commercial low-slope roofs fall into one of four single-ply membrane types:

• Thermoplastic polyolefin (TPO)
• Polyvinyl chloride (PVC)
• Ethylene propylene diene monomer (EPDM)
• Ketone ethylene ester (KEE)

TPO is a commonly used membrane in the United States because it offers a low upfront price point and provides generally acceptable performance in most applications. But upfront cost does not often tell the full story, and long-term performance under a variety of conditions should be considered when specifying a new system.

KEE-based membranes that meet relevant ASTM testing standards have demonstrated exceptional puncture and tear resistance compared to TPO, PVC and EPDM membranes. This is due to the inclusion of a strong fiber reinforcement layer and a minimum of 50% KEE polymer in material construction, per the ASTM standard. Other membrane materials don’t often meet the same level of high performance.

The difference can be made clear in the aftermath of a major storm. KEE membranes are better able to resist puncture and abrasion from flying debris or foreign objects as described earlier. With exceptional tear resistance, KEE membranes may also be less likely to tear or rip at the seams or points of fastening along the roof’s perimeter and corners, reducing the chance for wind uplift and total roof failure.

When in doubt, you can consult relevant codes and standards for guidance. For example, the FM Global 1-90 standard (FM 1-90) is a widely recognized benchmark for wind uplift resistance in commercial roof systems, and it’s often cited in manufacturer specifications, insurance requirements, and local codes. FM 1-90 indicates a roof system can withstand uplift pressures of 90 pounds per square foot. Many insurers require FM-rated assemblies in high-wind zones, and specifying an FM-approved system may positively influence insurability and risk assessment.

Systems that meet this standard can generally be relied upon for good performance in extreme weather conditions.

Your building envelope should be prepared for whatever Mother Nature throws at it. From common storms to more severe weather events, your operational security and business continuity depend on it, and your roof system represents one of the best opportunities to provide critical protection.