FM Approved

FM Approved is a certification mark issued by FM Approvals, the testing and certification arm of FM (formerly FM Global), a mutual commercial property insurer based in Johnston, Rhode Island. FM traces its origins to 1835, when New England mill owners led by Zachariah Allen formed a mutual fire insurance company built on loss prevention. FM operates a large research campus in West Glocester, Rhode Island, where it tests fire, explosion and natural hazard performance, including how building components behave in hurricane conditions.

In roofing, FM Approved status is one of the most widely recognised benchmarks for commercial low-slope roofs, both in North America and internationally.

What approval means

A product or assembly earns FM approval by:

• passing tests to a published FM Approvals standard
• undergoing audits of the manufacturing facility, with follow-up audits to confirm that production continues to match the tested product

Approved products and assemblies are listed in FM's online directories. For roofs, the RoofNav tool lists approved roof assemblies and components.

Roofing standards

Key FM Approvals roofing standards include:

• FM 4470 – single-ply, modified bitumen, built-up and liquid-applied roof assemblies, evaluating fire, wind uplift, hail, leakage, foot traffic and corrosion
• ANSI/FM 4474 – simulated wind uplift testing
• ANSI/FM 4473 – impact resistance of rigid roofing using ice balls
• 4475 – roof components for hail-prone areas

Ratings

Approved roof assemblies typically carry a designation such as Class 1-90. "Class 1" refers to meeting FM's fire criteria (including interior fire spread and external fire), and the number is the wind uplift rating in pounds per square foot (90 psf is about 4.3 kPa). Hail ratings may be shown as moderate or severe hail.

Who uses it

• FM-insured properties are generally required to use FM Approved roof systems installed according to FM loss-prevention data sheets.
• Specifiers and owners outside FM's client base often use FM approval as a quality benchmark.
• Code officials in the US may accept FM test data as evidence of compliance, since codes reference FM 4474 among wind uplift test methods.

Limits

FM approval applies only to the exact assembly listed: deck, insulation, fasteners, adhesives and membrane. Substituting components can void the approval. Approval also reflects FM's loss-prevention priorities, which can be stricter than local building code minimums in some respects and different in others.