Tip #18 - hour by hour...
NFPA 99-2010: 22.214.171.124.2* (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. perhpaps just 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.