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Community and Q&A

Metal roofing

TeacherCreature | Posted in Building Code Questions on

My metal roof was installed on 1X2 purlins. All I see on line refers to 1X4 purlins. Do I have a problem? The crew who installed had a multitude of problems and inspection did not pass. I don’t think the inspectors knew the purlins were the smaller size. I live along the Gulf Coast and insurance requires that the installation be proper. Can you advise? I need to know quickly as I am in the middle of getting my roof fixed. Thanks

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  1. Expert Member
    ARMANDO COBO | | #1

    I’m going to take a guess that you mean Battens and not Purlins. Battens are applied over the roof decking/rigid foam and purlins over the rafters. Not all metal roofs are created equal; some are required to be installed over battens, others over decking and others can go either. You need to find from the manufacturer which way you need to go.
    If we install metal roof over a ventilated attic, we will not use battens, as there is no need for it, unless you have a potential for ice damming with little insulation at the attic perimeter, which I doubt you'll have that problem on the golf coast. :-))
    To install metal roofing over conditioned attics or cathedral ceilings, we install rigid foam on top of the roof decking, so we need to install 1x4 battens to create solid structure for attachment and a thermal break. I don’t spec out 1x2 battens because the wood easily splits when installed, therefore it renders the structural hold useless.

  2. Seabornman | | #2

    Do you have name of roofing manufacturer? Check their website for requirements. Were purlins installed over a solid plywood or osb deck? Do you know what length screw they used and how purlins were attached?

  3. Expert Member
    ARMANDO COBO | | #3

    A second thought came to mind. If you are on the golf coast, you may need load design for 130-150 MPH winds, so you may be better off selecting an Energy Star metal roof, with high solar reflectance designed to be installed over decking. Also, the pitch of the roof dictates wind load reactions. You may need to consult with manufacturer or an engineer.

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