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The insulation or coverboard surface used for the installation of membrane shall be planar and free from debris. Any gaps shall be corrected prior to application of membrane. No insulation or coverboard panels should be less than 12" square when adhered or 24" square when mechanically attached.

Mechanical Attachment All base insulation layers over steel deck shall be mechanically attached with sufficient fasteners and stress plates to meet the uplift requirements for the project. Fastener density shall be increased at perimeters and corners as required by code and the project requirements. At a minimum, fastener density shall be increased by 50% at the perimeters and 100% at the corners, providing there is no parapet with a height less than 36". Fasteners shall penetrate the top flange of the deck a minimum of 3/4". To ensure securement to the deck, fasteners shall be sized to penetrate the bottom flute by 3/4". Fasteners shall be fully seated but shall not be overdriven to damage the insulation or coverboard surface. Fasteners and stress plates shall be installed in compliance with the recommendations of both the fastener and insulation manufacturers. Where holes must be predrilled, such as gypsum and concrete, deck debris must be cleaned from the insulation surface prior to application of the roofing membrane. When projects are insured by or specified under the requirements of FM Global the requirements under the relevant RoofNav number and the related Loss Prevention Data Sheet shall be followed. For more information, visit www.roofnav.fmglobal.com/.

CertainTeed provides a complete line of FlintBoard roof insulations and reserves the right to accept or reject another manufacturer’s insulation as an acceptable substrate for attachment of a CertainTeed Commercial Roof System. CertainTeed Corp. does not warrant performance of another manufacturer’s insulation unless such approval is granted in writing by CertainTeed in advance of installation.

Recover Considerations

A recover is the application of a new roof over an existing roof. If a roof installation is a recover, the existing roof assembly must be a suitable substrate for the application. Most codes limit recovers to one additional roof. An evaluation of the combined live and dead loads should be carried out by a structural engineer prior to any application over an existing roof. Loading requirements may have changed since the original roof application increasing the live load requirements due to historical snow loading data.

The existing roof should be evaluated for moisture and for adhesion to the underlying substrate. Adhesion can be evaluation with either a vacuum test or bonded pull test as detailed in the FM Global Loss Prevention Data Sheet 1-52 or the vacuum test detailed in the ASTM E 9071. Moisture analysis can

1ASTM E 907: Standard Test Method for Field Uplift Resistance of Adhered Membrane Roofing Systems


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