New Factory Mutual design guidelines spur debate at the International Roofing Show

March 01, 2007 |

For nearly two decades, Johnston, R.I.-based commercial and industrial property insurer FM Global has been publishing design guidelines aimed at reducing the chance of property loss due to fire, weather conditions, and failure of electrical or mechanical equipment.

The design guidance, which goes above and beyond building codes for building design, has become the de facto design standard for many AEC professionals, especially those working on projects in high-wind regions.

But recent updates to three of FM Global’s roofing-related data sheets—1-28, Design Wind Loads; 1-29, Roof Deck Securement and Above-Deck Roofing Components; and 1-52, Field Uplift Tests—have spurred debate among members of the National Roofing Contractors Association.

In particular, members of NRCA’s Technical Operations Committee are voicing their concerns over increased responsibility and potential liability placed on roofing contractors. The TOC presented its opinion during an education session at the International Roofing Expo, held earlier this month in Las Vegas.

“I seriously doubt that we as roofing contractors will be able to meet the FM guidelines,” said Mark Graham, NRCA’s associate executive director of technical services, during the session. As an example, Graham pointed to new FM language that calls for more stringent steel deck span requirements, including the use of heavier gauge deck and more bar joists.

“FM wants to turn roofing contractors into structural engineers,” said Graham. “The potential liability is a serious concern.”

TOC members also spoke out against FM Global’s requirement, under data sheet 1-29, for field uplift testing using the ASTM E907 test apparatus in hurricane-prone regions on FM-insured buildings.

“The problem with this test method is that anyone with experience can make it pass or fail, based on their mood that day,” said Graham. “The last thing we want is to let an unreliable post-installation test determine the success or failure of a project.”

Graham said the TOC plans to meet with FM Global officials to discuss the updated guidelines.

The guidelines can be download for free at

Here’s a recap of other news from the International Roofing Expo:

• Online wind-load calculator debuts at IRE. Now there’s no excuse for design and construction professionals to miscalculate wind loads for roof systems. A free online wind-load calculator instantly determines the wind speed and design wind loads for roofs based on a building’s location, roof area, configuration, roof height, exposure, and occupancy. The tool was developed by NRCA in conjunction with the Midwest Roofing Contractors Association and the North/East Roofing Contractors Association.

• NRCA takes its popular EnergyWise Roof Calculator online. Comparing the energy performance of different roof assemblies will soon become a snap. NRCA officials are putting the finishing touches on a free online version of the EnergyWise Roof Calculator. Set to launch in April, the program allows AEC professionals to construct virtual roofing assemblies to evaluate thermal efficiency and estimate heating and cooling costs.

• Roof coatings manual offers do’s and don’ts on coating specification and application. The NRCA’s new “Guide to Roof Coatings” offers prescriptive advice on specifying and applying roofing coatings. The 35-page guide provides an objective discussion about the application of various types of coatings, where they may best be used, and what preparations are essential for their successful performance.

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