Tech Today

FM RoofNav

In March, FM Approvals debuted RoofNav, a Web-based version of its Approval Guide. RoofNav offers a simplified means of determining roofing product and roof system compliance with FM Approvals' guidelines and standards.

How it works

RoofNav, which can be accessed at, allows users to access roofing-specific portions of the Approval Guide through a series of online tools and comprehensive search capability; it also provides access to FM Global's Property Loss Prevention Data Sheets. Using RoofNav, users can configure specific components into roof systems and determine the systems' approval classifications.

Upon accessing the site, background information regarding RoofNav is available and registered users can log in. New users also can register from this screen.

There are two user levels of RoofNav: a free-of-charge "registered" user level and a premium content, fee-based "subscriber" user level.

The registered user level provides an account-management feature, contacts list, notepad and list of saved projects; background information regarding FM Approvals and RoofNav; a limited products search feature; ratings calculator; and glossary.

The background information page includes information about FM Approvals' testing and approvals, general information about approved components and assemblies, and common metric conversions. The product search feature allows users to search for specific approved manufacturers and products.

The ratings calculator determines roof assemblies' design wind-uplift values based on user input variables for basic wind speed, ground roughness, exposure to windborne debris, building envelope enclosure and building dimensions. FM Approvals reports the calculation procedure used in RoofNav is based on ASCE 7-98, "Minimum Design Loads for Buildings and Other Structures."

RoofNav's subscriber user level includes all the features of the registered user level plus expanded product search capabilities, an assembly search capability and access to roofing-related data sheets.

With the assembly search, users can search for specific approved roof assembly configurations that have approvals for wind uplift, internal fire, external fire and hail resistance. These searches also can be refined to specific manufacturers and product names. The data sheets feature allows users to access current versions of 12 of FM Global's most frequently accessed roofing-related Property Loss Prevention Data Sheets.


RoofNav is a substantial improvement over the paper-based versions of the Approvals Guide and Property Loss Prevention Data Sheets. Although the previous paper-based versions usually were outdated by the time they were available to users, RoofNav provides current, up-to-date information. Also, RoofNav's product and assembly search features, which previously were unavailable with the paper-based versions, will be valuable to most users. Such searches particularly are useful in identifying products, manufacturers or specific substitutions that are allowable within specific approvals.

One downside of RoofNav is it is a relatively complex application and not completely intuitive and easy to use. This partly is because of the complex nature of FM Approvals' guidelines and approvals and large number of roofing products and roof assemblies FM Approvals addresses. FM Approvals is offering several Web-based training programs to familiarize users with FM Approvals' guidelines and RoofNav. I encourage all users of RoofNav to participate.

Also, RoofNav currently does not identify roofing products, roof systems or manufacturers that had been approved at one point but are not currently approved. Rather, RoofNav only identifies current approvals. For this reason, RoofNav cannot be used for historical determinations of approvals.

Overall, RoofNav is a useful tool for roofing professionals, and FM Approvals should be complimented for its efforts. If you are involved in the design of roof assemblies, I encourage you to look into RoofNav.

Mark S. Graham is NRCA's associate executive director of technical services.


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