FM Global Data Sheet 1-29, titled “Roof Deck Securement and Above-Deck Roof Components,” provides detailed guidance for designing and securing commercial roof assemblies against wind uplift and other property-loss risks. It is especially important for commercial and industrial buildings where FM Global requirements or FM Approved roofing systems are specified.
The current Data Sheet 1-29 covers both roof deck securement and the installation of components above the roof deck. FM Global identifies it as guidance for wind resistance and fire classification of roofs. The document is intended to be used with FM Global Data Sheet 1-28, Wind Design, and FM’s RoofNav system when selecting approved roof assemblies.
What Does FM Data Sheet 1-29 Cover?
One of the primary purposes of Data Sheet 1-29 is to establish how the roof deck and roofing components should be secured so they can resist expected wind forces.
For steel roof decks, the document addresses the span and attachment of the deck to supporting structural members. This includes considerations such as deck type, fastener or weld patterns, deck securement, and allowable uplift pressures. These requirements are particularly important because the roofing membrane can only perform as intended if the underlying deck and structural attachments can transfer wind loads safely.
Data Sheet 1-29 also addresses components installed above the deck, including:
- Roof covers and membranes
- Insulation
- Cover boards
- Vapor retarders
- Air barriers
- Mechanical fasteners
- Re-roof and re-cover assemblies
- Ballasted or adhered roof components
- Certain roof leakage detection systems
The requirements can vary according to the roof assembly, deck construction, fastening method, wind rating, and roof zone.
Wind Uplift and Roof Zones
A major consideration in FM roof securement is wind uplift. Roof areas do not necessarily experience the same wind pressures. Perimeter and corner zones can experience greater uplift than the field of the roof.
Data Sheet 1-29 provides methods for adjusting securement in different roof zones. For certain assemblies, fastening or attachment spacing must become tighter in higher-wind-pressure areas. For example, the document provides specific approaches for mechanically fastened and adhered systems in Zones 2 and 3.
This means a commercial roof should not automatically use the same fastener spacing everywhere. The required securement must be based on the applicable FM requirements and the specific approved assembly.
FM Approval and RoofNav
Another important point is that Data Sheet 1-29 does not simply provide a universal fastener pattern that applies to every roof. FM Global uses FM Approval ratings and RoofNav assemblies to establish tested and approved combinations of roofing components.
Contractors and building owners should therefore verify that the proposed membrane, insulation, cover board, fasteners, adhesives, and deck configuration correspond to an appropriate FM Approved assembly and wind rating.
For re-roofing and recover projects, Data Sheet 1-29 specifically calls for evaluation of the existing roof deck span and securement before selecting an appropriate RoofNav assembly. Existing construction may not have been designed using the same assumptions as a new roof system.
Why Does FM Data Sheet 1-29 Matter?
Proper roof securement is critical because a roof system can suffer major damage if wind forces exceed the capacity of the deck, fasteners, membrane attachment, or other components. A failure at one layer can contribute to progressive damage across the roof assembly.
For commercial property owners in Florida and other high-wind areas, understanding FM requirements can be particularly valuable when an insurer, project specification, architect, or engineer requires FM Approved construction.
In short, FM Data Sheet 1-29 covers the securement of steel roof decks and above-deck roofing components, including membranes, insulation, cover boards, vapor retarders, air barriers, and fasteners. It establishes guidance for wind resistance, roof-zone securement, deck attachment, and approved roof assembly selection. The document should be applied together with the applicable FM Global wind-design requirements and RoofNav listings rather than treated as a standalone generic roofing specification.
For a commercial roof replacement, restoration, or new installation, a qualified roofing contractor should verify the existing deck, required wind uplift rating, FM Approval requirements, and project-specific assembly before work begins.
Commercial Roof Inspections
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