Protecting Critical Assets from the Destructive Forces of High Winds
As a seasoned roofing professional, I’ve witnessed firsthand the devastation that high-wind events can wreak on buildings and their rooftop equipment. From flying HVAC units to whipping lightning rods, the consequences of inadequately secured roof-mounted assets can be catastrophic – both in terms of property damage and potential loss of life. As the frequency and intensity of severe weather continue to rise, it’s crucial that building owners, facility managers, and roofing contractors take proactive measures to safeguard these mission-critical systems.
In this comprehensive guide, we’ll explore a range of practical strategies and industry-proven techniques to ensure your roof-mounted equipment stands firm against the destructive forces of high winds. Drawing insights from extensive research and case studies, we’ll provide you with the essential knowledge to optimize the resilience of your rooftop systems and minimize the risks associated with extreme weather events.
Assessing Wind Loads and Equipment Vulnerabilities
The first step in securing your roof-mounted equipment is to accurately determine the wind loads it will face during a high-wind event. The American Society of Civil Engineers (ASCE) 7-05 standard provides the necessary guidance for calculating both lateral and wind-uplift loads on individual components.
When performing these calculations, it’s important to incorporate a suitable safety factor to account for potential uncertainties. For critical facilities like hospitals and schools, a minimum safety factor of 3 is recommended, while a factor of 2 should be used for all other buildings.
“Failure of rooftop equipment during high-wind events is often the result of inadequate consideration for wind loads and improper anchoring techniques,” explains Thomas Lee Smith, a building consultant and member of the Federal Emergency Management Agency (FEMA) Mitigation Assessment Team. “By accurately determining the expected wind loads and designing the attachment system accordingly, you can significantly reduce the risk of catastrophic failures.”
Optimizing Anchoring Systems and Equipment Integration
Once the wind loads have been established, the next step is to ensure your roof-mounted equipment is properly secured and integrated into the building’s structure. This involves a multi-faceted approach that addresses the various components and elements at play.
Ductwork and Mechanical Penthouses
Exposed ductwork on rooftops is highly susceptible to wind damage, as even properly anchored systems can succumb to the destructive forces of high winds and flying debris. Whenever possible, Building Teams should avoid installing exposed ductwork in high-wind regions. If it’s an absolute necessity, the ductwork must be custom-designed with heavy-gauge sheet metal and robust anchoring, such as bolted steel angles that wrap the ducts.
For critical facilities like hospitals and schools, the construction of a dedicated mechanical penthouse can provide an additional layer of protection for vital rooftop systems. These enclosed structures shield equipment from the direct impact of high winds, while also facilitating easier access for maintenance and repairs.
Vibration Isolators and Condenser Units
When mounting equipment on vibration isolators, it’s crucial to specify spring isolators that can accommodate both lateral and uplift resistance. The FEMA Mitigation Assessment Team found numerous instances where equipment was blown off buildings because the isolators were not designed to withstand wind-induced uplift.
Rooftop-mounted condenser units are also highly vulnerable to high winds, as they are often placed on simple wood sleepers that provide little to no resistance. To properly secure these units, the base should be anchored to a dedicated equipment stand, which is then firmly attached to the roof structure. Wrapping the unit with metal straps and securing the strap ends to the stand with side-by-side screws or bolts is an effective anchoring strategy.
Fans, Cowlings, and Access Panels
Poorly anchored fan systems and equipment cowlings can become deadly projectiles during a high-wind event. Fans should be secured to their curbs with at least two screws on each side, while cowlings smaller than four feet in diameter should be attached to the curb using 1/8-inch stainless steel cables (three-sixteenth-inch cables for larger cowlings).
Even when the primary equipment is well-anchored, access panels and other small ancillary components can still pose a risk if not properly fastened. Building Teams should install a hasp or other locking device approved by the equipment manufacturer to prevent these elements from becoming windborne.
Corrosion Prevention and Lightning Protection
To ensure the long-term resilience of your roof-mounted equipment, it’s essential to consider the effects of corrosion and the integrity of lightning protection systems.
All exterior-mounted equipment, including stands, anchors, and fasteners, should be constructed from non-ferrous, stainless steel, or steel with a minimum G-90 hot-dip galvanized coating. This helps prevent corrosion-induced failures that can compromise the anchoring system over time.
Failure of lightning protection systems during high-wind events is often due to anchors that open up, releasing the conductor cable, or completely debond from the roof. To mitigate this risk, Building Teams should specify looped connectors instead of pronged units and mechanically fasten them to parapets using #12 screws with a minimum 1¼-inch embedment. For roofing systems other than metal, the connectors should be secured with asphalt roof cement or a liquid sealer, depending on the roof type.
Incorporating Resilience into Roofing Projects
As you plan and execute roofing projects, it’s essential to adopt a holistic approach that prioritizes the resilience of the entire building envelope, including the roof-mounted equipment. By collaborating closely with building owners, facility managers, and other stakeholders, roofing professionals can ensure that the specified materials, anchoring systems, and maintenance protocols effectively safeguard critical assets against the ravages of high winds.
At Roofers in Northampton, we understand the vital importance of proactive measures to protect roof-mounted equipment. Our team of experienced professionals is well-versed in the latest industry standards, best practices, and emerging technologies that can enhance the resilience of rooftop systems. Whether you’re planning a new construction project or in need of comprehensive roof maintenance and repair services, we’re here to help you fortify your building against the unpredictable forces of nature.
Conclusion: Preparing for the Unexpected
As the frequency and intensity of severe weather events continue to increase, the importance of safeguarding roof-mounted equipment cannot be overstated. By implementing the strategies and techniques outlined in this guide, you can effectively minimize the risks posed by high winds and ensure the long-term resilience of your critical rooftop assets.
Remember, the time to act is now. By taking proactive measures to secure your roof-mounted equipment, you can protect your building, its occupants, and your business from the devastating consequences of a high-wind event. Contact the roofing experts at Roofers in Northampton today to discuss your specific needs and explore customized solutions that will safeguard your roof-mounted equipment for years to come.
