NFPA 99-2010: 5.1.3.3.2* (4) If indoors, they shall be constructed and use interior finishes of noncombustible or limited-combustible materials such that all walls, floors, ceilings, and doors are of a minimum 1-hour fire resistance rating.
The 2012 and previous editions of the required a 1-hour door. Perhaps this was an oversight by the NFPA committee who in later editions reduced the requirement to 45 minutes. Surveyors will likely look for a 60 minute door.
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