Don’t let the roof’s edge be the weakest link

By Jenny Yu.  

From wind uplift to water intrusion, choosing the right edge metal is critical for roof performance and structural integrity. 

Edge metal may only account for a small portion of a roof’s total surface area, but its role in protecting the structure from wind uplift and water intrusion is significant. As Jason Hildenbrand of Hickman Edge Systems and Carlisle Architectural Metals (CAM) explains in this Read Listen Watch® (RLW) episode, edge metal helps anchor the membrane, reinforce the roof structure and distribute wind forces more evenly. 

“It's really about how wind reacts on a building,” Jason shared. “As wind approaches the building, it's going up, down, around the sides.” This dynamic creates extreme pressure at the most vulnerable points: the roof perimeter and corners. 

“Minor differences in wind speed can have a significant result on the force that's exerted on the roof,” he continued. “That wind uplift pressure increases exponentially with the wind speed. So, at two times the wind speed, the pressure is actually four times what it was previously. At three times, it's nine. At four times, it's 16.” These rapidly increasing forces are why well-designed edge metal systems are critical at perimeter zones, where the risk is highest. 

What happens when edge metal fails?  

While edge metal is designed to protect the roof, it can also become a primary point of failure if not properly installed or maintained. “In most cases, when we see a roof failure from a storm or wind event, it starts at the edge, from improperly designed or installed edge metal,” Jason shared. “When that edge fails, the rest of the roofing components really can't withstand those loads.” 

This can result in a domino effect that leads to membrane detachment, water infiltration, and costly structural damage. Jason referenced a case study from an insurance company, AIG, that highlighted a roof failure incident caused not by a direct hurricane hit, but by winds from the outer bands of storm winds. 

“There were about 7,000 square feet of roof covering loss. The roofing cost alone was about $70,000. There was also a $1.7 million content claim and a $1.7 million business interruption claim. We're talking about $4 million in loss,” Jason said. “And what they reported back was that proper flashing securement would've likely resulted in no loss.” 

Jason added, “When you look at it, a roof is generally 10% of the building cost. The perimeter edge is 1% of that. So, 1% to have a tested code-compliant, warranted system to avoid a $4 million potential liability is really cheap insurance, right?” 

How to ensure your edge metal performs as designed 

The best way to avoid edge-related failures is to install tested, code-compliant systems. 

“I would prefer that they went with a pre-engineered option,” Jason advised. But regardless of the system chosen, testing and compliance are of the utmost importance. “There are the testing options for making sure that the edge system is compliant and can meet those pressures.” 

He recommends checking for testing through agencies like UL, Intertek or NRCA. Some membrane manufacturers also certify contractors to fabricate tested systems. 

Read the transcript, Listen to the podcast or Watch the webinar to learn more about edge metal system best practices.