FM Approvals (FM) continues to introduce revisions to its standards that are designed to help reduce insurance risk and provide greater safety factors on FM insured buildings.

These efforts are laudable, particularly in the eyes of property owners who use FM Global or an insurance carrier associated with the company. However, these revisions can also have a significant impact on designers’ specifications in the new construction market — and for roofing contractors, who may be the “designer of record” on re-roofing projects.

Over the years, the number of roof fasteners required on the corners and perimeters of mechanically attached roof systems has been increased to meet design wind loads. It now appears that FM Approvals is looking at the roof system/roof deck interface with an eye toward reducing the stresses on steel roof decking. Recent changes to FM Approvals Standard 4470 address the potential for “overstressing” the roof deck and a variety of other issues.

At the time that roofing system and component suppliers were officially notified of the revisions to FM 4470 by FM Approvals (Oct. 18, 2012), there appeared to be little in the way of transition plans or guidance for the roofing industry.

Fortunately, Mark Tyrol, PE of FM Approvals will be making a presentation on the changes to FM 4470 at RCI Inc.’s 28th International Convention & Trade Show on March 14-16 in Orlando, FL. FM Approvals representatives have also conducted a number of face-to-face meetings with code specialists employed by the larger roof system manufacturers.

In the meantime, SPRI has published a second, detailed bulletin (No.2-12) that includes further clarifications for the design and contractor communities on important changes recently made to FM Approvals Standard 4470. SPRI represents sheet membrane and component suppliers to the commercial roofing industry.

The second SPRI bulletin emphasizes that meeting the entire criteria established in FM 4470 is not a requirement of the 2009 International Building Code® (IBC). The SPRI document clearly points out sections of the IBC that determine the requirements for building design, including explanations of Sections 1504.3, 1504.3.1 (Wind Resistance) and 1504.7 (Impact Resistance). In these Sections, the IBC references specific FM Approvals test procedures.

However, in general, the IBC requires testing to be conducted by an approved testing agency. Many “approved” third-party test laboratories are located throughout the country to conduct roof system testing and issue final test reports that the manufacturer can then use as documentation to show compliance with the IBC.

SPRI bulletins 1-12 and 2-12, an Excel spreadsheet, and other information on the revisions to FM 4470 can be downloaded at

 In short, roofing contractors are encouraged to identify and comply with the IBC, along with the designer of record and/or authorities having jurisdiction related to the specifications. When the building or tenant is FM insured, SPRI recommends that the appropriate FM field office be contacted prior to starting any work to reconfirm acceptance of the roofing system to FM requirements.