Seven questions to ask when specifying fire-rated glazing in doors

The 2012 International Building Code (IBC) requires fire-rated glazing to include a multi-faceted product label code that building and design professionals can reference to quickly evaluate a product’s performance capabilities. To guide appropriate use, it is necessary to understand what these markings mean, and what implications they have for specification.

The first part of the label code is a letter indicating which applicable test standard the glass has passed, and where it is considered suitable for use:

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“D” indicates doors (i.e. glazing meeting National Fire Protection Association [NFPA] 252, Standard Methods of Fire Tests of Door Assemblies);
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“OH” indicates openings (i.e. glazing meeting NFPA 257, Standard on Fire Test for Window and Glass Block Assemblies, and both the fire endurance and hose stream requirements of the test standard); and
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“W” indicates walls (i.e. fire-resistive glazing meeting ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials, along with NFPA 251, Standard Methods of Tests of Fire Resistance of Building Construction and Materials, and UL 263, Fire-resistance Ratings).

The next two letters in the code sequence, if present, will indicate conformance with certain test criteria:

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“H” indicates glazing meets the hose stream test (required for all windows and door assemblies with ratings of 45 minutes or more); and
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“T” indicates glazing meets temperature rise door criteria (per IBC section 715.4.4.1, “Glazing in Doors”).

The last marking on the fire-rated glazing label is a two- or three-digit number showing the fire rating in minutes (e.g. 45, 90, or 120). The given number corresponds with manufacturer testing in accordance with national fire test standards.

Thus, when the product label code is read, it is possible to quickly determine whether a given product has passed the necessary tests for the fire door application at hand. For example, when looking at the sample fire-rated glass label above, the “D-H-60” and “OH-60” designations show the product:

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is suitable for use within door assemblies and openings;
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has passed the required hose stream test; and
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is fire-rated for 60 minutes.

If a fire-rated glazing product has been tested to multiple standards, as evidenced in the sample label, it carries multiple markings indicating its suitability for those uses.