This Quick Question has come up a few times lately:

In an existing fire door, can a vision panel be added or enlarged in the field, assuming that the correct glazing is installed?

As I mentioned in a recent article published in Locksmith Ledger, there are two types of fire door alterations referenced in NFPA 80 – Standard for Fire Doors and Other Opening Protectives:

  • Job Site Preparations: These are changes made in the field that are specifically allowed by NFPA 80 – Standard for Fire Doors and Other Opening Protectives.
  • Field Modifications: This work must be approved in advance by the listing laboratory (for example, Underwriters Laboratories or Intertek) and can then be done without requiring the door or frame to be relabeled.

The types of alterations addressed as job site preparations typically include round holes for hardware, undercutting of wood and composite doors, and installation of protection plates – refer to NFPA 80 for the complete list and limitations.  Adding or enlarging a vision panel would not be allowed as a job site preparation.

It’s possible that a listing lab could allow a modification to a vision panel as a field modification, but approval would have to be requested in advance through the door manufacturer.  If the alteration can not be performed as a field modification, another possibility is to have the door relabeled after the work is completed, but that should be coordinated before work begins.  Adding or enlarging the vision panel in an approved shop is another option, although provisions must be made for fire safety in the building for the period of time that the door will not be in place to perform as part of the fire door assembly.

Have you had experience with this type of modification on an existing fire door?  How was the work performed?

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