How does a metal roof stand up to Mother Nature? Tony Bouqout of the Metal Building Manufacturers Association writes a compelling article about the durability of metal roofing.
Standing Seam Metal Roofs Offer Advanced Protection Against Fire And Wind
By Tony Bouquot, Metal Building Manufacturers Association
An increasing number of industry experts are proactively responding to these challenges by specifying more resilient building products. Standing-seam metal roofs, which offer superior protection against the elements, fit this category.Nationwide, severe weather and geological events are causing astronomical property damage. The consequence: communities strained by a loss of resources, security and access to shelter. Certain areas are so devastated that recovery seems next to impossible (think New Orleans after Hurricane Katrina in 2005). For other communities, an increased awareness sets in, inspiring citizens to turn disaster into opportunity—to rebuild better and stronger.
“Today’s metal roofing is a strong choice for even the most vulnerable structure,” asserted Robert Zabcik, PE in a recent white paper titled “Metal Roofing Performance and Wind Events.” He added, “It is well documented that buildings with secure, storm-resistant roofing materials like metal are less prone to damage from hurricanes and high-wind events. Metal roofing’s strength and durability provide safety and security for building owners and occupants alike.”
Metal’s Ample Advantages
Natural catastrophes increased economic and insured losses for a second consecutive year in 2018, to an estimated $92 billion overall economic total. These findings were cited in a 2018 report titled “Weather, Climate & Catastrophe Insight” by Aon, a global professional services firm. When compared to annual data from 2000-2017, last year’s economic losses proved to be 97 percent higher than the median ($46 billion).
When specifying metal roofs to customers it is important to explain the system’s significant attributes. They may not understand that standing-seam metal roofs (SSMRs) weigh about 1½ pounds per square foot, lessening the demand on a building’s structural support systems (a crucial benefit in earthquake-prone areas). These systems also provide a weathertight seal that accommodates expansion and contraction.
Owners also need to know that SSMRs offer durable, long-term protection against virtually any type of weather, such as high winds, snow, hailstorms and wildfires. In hurricane conditions they are rated to withstand winds of 140 mph or higher (and have proven to remain secured to structures when properly installed).
Metal roofs are renowned for their sustainability and energy performance features, properties of which many architects and owners are unaware. When separated from other materials during the demolition process, these systems are 100 percent recyclable. Plus, with advanced coating systems, they reflect heat rather than absorb it—effectively cutting cooling costs and increasing building occupants’ comfort.
“Designs that provide green space and the use of cool and green roof technologies in cities can reduce heat-island effects, producing multiple benefits and cost reductions by helping to reduce emissions and air pollution, human health risks, and economic losses due to reduced labor productivity,” cited researchers in the Fourth National Climate Assessment, released in 2018 by the National Oceanic and Atmospheric Administration. While such adaptive planning and implementation activities are occurring in the public, private and nonprofit sectors of the U.S., widespread adoption is not yet commonplace.
Wind Resistance Blows Away The Competition
Durability also tops the list of key metal roofing benefits. According to a 2014 study conducted by the Metal Construction Association and the Zinc Aluminum Coaters Association, the projected service life of certain SSMRs is a minimum of 60 years. “This is the longest service life of any commonly used roof system in the marketplace,” notes Vincent Sagan, PE, senior staff engineer for the Metal Building Manufacturers Association (MBMA). The association, established in 1956, advocates for the usage of metal building systems and regularly collaborates with other industry partners to promote metal roofing solutions.
Wind damage to commercial property is a serious growing concern, says Dwayne Sloan, director of principal engineers and regulatory services for UL’s Building and Life Safety Technologies Division. In coastal regions, shearing winds produced by hurricanes top the list of weather-related structural challenges.
In a green building magazine article published earlier this year, Ken McLauchlan shared that his company’s engineered metal roofing systems were effective against hurricane-force winds of up to 150 mph. He also alluded that metal roofs, paired with quality buildings, are essential in safeguarding structures against severe weather events and natural disasters.
While metal roofs are compatible with all building types, they naturally complement the inherent structural integrity of metal building systems. Economical design and speed of construction are among the top reasons these custom-engineered buildings are the most popular low-rise commercial construction solution in America today.
“We find that metal buildings are more efficient to construct than conventional structures because all of the wall panels, the roofing system, and all of the trims come along with the structural system. It’s all designed to go together and it’s very efficient to build,” comments Art Hance, owner and President of New Jersey-based Hance Construction.
Fierce Fire Protection
In an October 2018 study about fire losses in the U.S., the National Fire Protection Association reported approximately 500,000 fires occurring in 2017—a 5-percent increase compared to 2016. Nearly half of the estimated $23 billion in property damage is attributed to structure fires.
Since SSMRs have a Class A fire rating due to their non-combustible properties, according to the International Building Code (IBC), they help to preserve structures and the people/contents inside them. “In many cases with metal buildings, the roof system doesn’t have to be rated because it’s Type IIB construction,” Sagan reveals. He further explains an advantage that is not well-known among building owners. “Under certain occupancies, if the lowest elevation of the roof system is above 20 feet, fire protection of the roof structure is not required. This can result in huge savings for the owner.”
Collaboration between industry stakeholders is important for developing resources that educate building owners and developers about metal roofing best practices. For example, MBMA’s “Fire Resistance Design Guide for Metal Building Systems” includes a section pertaining to photovoltaic systems (PV) on metal roofs.
In addition, MBMA is working on multiple projects specific to SSMRs. One study focuses on wind load cases to provide realistic panel load scenarios. “This should help recapture some of the current overly conservative treatment seen in some standards. Current standards assume a small tributary area-based uplift loading scenario occurring in all spans simultaneously. It also assumes simultaneous peak loading in all roof wind zones for panels that reside in multiple wind zones,” Sagan explains.
Last year marked the third-consecutive season of above-average hurricane activity in the Atlantic, according to CoreLogic’s latest “Natural Hazard Report.” In September, approximately 700,000 homes and businesses experienced catastrophic flooding and wind damage due to Hurricane Florence. With recorded wind gusts up to 105 mph, the Category 4 storm caused an estimated $20 billion to $30 billion in insured and uninsured losses. Weeks later, Hurricane Michael wreaked havoc along the Florida Panhandle with a 155-mph maximum sustained wind speed. Experts estimate up to $4 billion in residential and commercial insured losses caused by the tempest’s shearing winds and storm surge.
MBMA’s Fire & Insurance Committee is currently working toward making “common sense changes” concerning the fire testing of PV/solar panels on non-combustible metal roofs, says Sagan. He explains that simplification of some the fire testing requirements in the UL standards would decrease the amount of testing, thereby reducing the cost of the construction process and possibly encouraging new innovative PV for metal roofs. The committee’s long-term goal is that the revised standards will be adopted into the IBC.
Also, through the collaborative efforts of the Insurance Institute for Business & Home Safety (IBHS) and MBMA, testing and analysis of hail impacts on metal roof panels is taking place to develop a definition of functional damage versus cosmetic damage. “We’re providing information to help the metal roofing industry, as well as the insurance industry, on defining levels of performance of metal roofing subjected to hail,” Sagan says.
He adds, “When it comes to these and other projects, MBMA’s involvement and research provide resources not just for our members, but for the entire construction industry. We’re invested in research that is real-world, practical and has a transformative impact. Guidelines we help to develop, such as guidelines that address snow loads on roofs with solar panels, can be used today as a framework to build resilient structures and systems for tomorrow.”
The adoption of improved industry standards and building codes is a laborious, painstaking process that often takes years. Persistence is vital to making updates that are both timely and forward-thinking. This, in turn, will help to ensure that new and retrofit metal roofs become more mainstream across all property types.
About The Author
Tony Bouquot is the General Manager of the Metal Building Manufacturers Association.