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Verifying Class-C Fire-Rating for Standing Seam Metal Roof

sidekickarchitects | Posted in Building Code Questions on

Hi All-
Most of my work in Southern California is with asphalt shingles, which are easy to achieve a Class-A roof. For a project I am working on now our clients have asked for standing seam metal roof panels and the supplier prefers to use Owens Corning Titanium UDL 30 as the underlayment. Although they have evaluation reports establishing this as a Class A fire-rated roof with shingles, they do not have reports for a Class C in combination with metal panels. Does anyone know of an underlayment for metal panels that has an actual evaluation report establishing a Class-C fire rating? The plan checker is requiring that documentation.

As a long shot, I would also love to know of an underlayment that IS warrantied for an unvented roof assembly, but I’m guessing that is a tall order.


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  1. kbentley57 | | #1

    Please correct me if I'm being dense, but isn't Class C a lesser rating than Class A?

    1. sidekickarchitects | | #2

      Yes indeed. All I need is an evaluation report stating that standing seam metal roofing with any underlayment meets class C (or better) fire rating. So far all of the evaluation reports that I have seen only rate the assembly with asphalt shingles

  2. kbentley57 | | #3

    If you search for "ICC standing seam metal roof", you'll get a ton of reports similar to this one. They should all have the information you need in regards to decking, panel thickness, and underlayments.

    1. sidekickarchitects | | #4

      Thank you!

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