FM Approved Roofing

The Hazards

Roofing systems are the first line of defense in the complete building envelope that includes the roof, walls, windows, doors and flashing. Roofing systems must be able to protect a structure from the natural hazards associated with the local environment, including rain, hail, snow, high winds, temperature extremes—even fire.

Wind rushing over a roof, for instance, produces lift, much like an airplane wing. This lift creates tremendous turbulence and dynamic stresses. Powerful eddies and vortices, which resemble horizontal tornadoes, churn along roof perimeters and corners. These forces can rip at roof covers, flashing, insulation and the underlying roof structure.

The failure of a building’s roof and other building envelope elements, including walls, windows and doors, can have a devastating impact from which a business may not be able to recover. When a roof is damaged or destroyed, the building contents can be exposed to flooding and contamination, further compounding the loss.

Loss prevention begins with knowledge. Most property loss, including those involving the roof, can be prevented. FM Global continues to work hard to help clients in wind-prone areas to improve their roofs and other components of the building envelope. FM Approvals is doing its part to help property owners avoid losses by continually improving Approval standards and by helping to make it easier for designers, architects and contractors to specify and install FM Approved roofing systems.

FM Approvals also works to provide Approval Standards and FM Approved products that support sustainable building practices, including green roofs (e.g., vegetative, light-colored covering), building-integrated photovoltaics (BIPV), and skylights for day lighting.

Testing Required for FM Approval

FM Approvals is a leader in certification and Approval of roof assemblies.

FM Approvals is the only organization in the world that tests complete roof assemblies when subjected to multiple perils such as fire testing above and below the deck, wind-uplift testing, hail-damage testing, accelerated weathering, water leakage, foot traffic and corrosion-resistance testing of metal parts.

A roof assembly is tested to meet:

• The interior fire performance requirements using the FM Approvals Construction Materials Calorimeter Test (the only such test in the world developed after many years of research and testing) adopted by NFPA as NFPA 276. It’s a pass/fail test giving the rating of Class 1 if the roof assembly passes.
• The exterior fire performance using the ASTM E 108 test method for an A, B or C rating.
• The wind performance using ANSI/FM 4474 for ratings starting from 60 psf up to 990 psf.
• Hail, corrosion and accelerated weathering performance using FM Approvals test methods for hail, corrosion and accelerated weathering. Ratings for hail are MH (moderate hail) and SH (severe hail).

The combined analysis of fire and natural hazards testing on a roof assembly assures the purchaser and building owner a fire-safe, wind-resistant roof capable of maintaining its integrity for many years.

To tailor an FM Approved roof to the needs of the facility owner, designer or contractor, we need to specify the fire and natural hazards ratings. For example, a rating for a roof assembly could be 1-180 A SH, where “1” represents a roof assembly that passed the interior fire test; “180” represents the wind performance rating for the roof in psf; “A” represents the exterior fire rating; and “SH” represents sever hail rating. All this information for all FM Approved roof assemblies is available in RoofNav (www.RoofNav.com).

Benefits and Availability

FM Approved roofing products and assemblies are listed in RoofNav, the FM Approvals web-based tool for roofing professionals. RoofNav takes the guesswork out of configuring an FM Approved roofing system by putting all roofing-related information, including a ratings calculator and related installation recommendations from relevant FM Global Property Loss Prevention Data Sheets, in one place.

Why choose an FM Approved roof assembly versus a non-certified product or design? An FM Approved roof means you get a tested roof assembly, not simply a collection of products and parts that may or may not perform as expected. Through RoofNav and properly installed FM Approved products, you get a roofing system that has been proven in extensive testing to perform as specified, including wind uplift, fire resistance and many other factors.

With an FM Approved roofing system, you are assured that the manufacturers of the components that make up that system have proven quality programs in place. For building owners and architects, when you demand an FM Approved roof assembly for your project, you are more than simply meeting basic code requirements—you are ensuring that the most important building envelope component will be fire-, wind- and hail-safe and protect your structure for many years to come. FM Approved roofing systems are specified and accepted by building owners, designers and code authorities throughout the world.

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