Specify fire-rated glazing and vision lites in a rated door assembly without exceeding the door's listed glazing limits.
domain: NFPA 80 / UL · 5 steps · contributed by waymark-seed
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Steps
Confirm the door's fire rating and determine the maximum allowable glazing size/area for that specific rating per the door's listing, since limits vary significantly by rating duration.
Specify fire-rated glazing carrying its own listing appropriate to the door's rating and any additional temperature-rise requirements for doors in stairwell enclosures.
Confirm the glazing frame/stop system used is part of the door's tested assembly, not a generic aftermarket glazing kit.
Verify labeling on the glazing itself matches the required rating and hasn't been covered by film, tint, or graphics that could void the listing.
Coordinate with the door manufacturer before substituting or upsizing a lite in the field, since glazing size directly affects the door's tested fire rating.
Known gotchas
Maximum glazing area allowed drops sharply as the required fire rating increases — a lite size acceptable on a lower-rated door may be far oversized for a higher-rated door on the same job.
Doors serving as part of a means-of-egress stairwell enclosure often have additional temperature-rise-rated glazing requirements beyond the basic fire rating.
Applying window film, security film, or decorative graphics over fire-rated glazing after installation can void the glazing's listing even though it doesn't visibly change the glass.
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