Q: Is positive latching required for any fire rated door in any occupancy classification? If so, are there any exceptions? What about double egress corridor doors; are they required to be positive latching? Are doors to restrooms required to be positive latching?
A: Yes, fire rated doors are required to positively latch no matter where they are installed, according to section 22.214.171.124 of the 2012 Life Safety Code. This section requires all fire rated doors to be compliant with NFPA 80, which requires positive latching hardware. This is a requirement for all occupancies, and is not specific to any one occupancy. There are no exceptions as far as I know: If the door is a fire rated door assembly then it needs to positively latch.
This raises the awareness about barriers that do not require fire rated doors. It is not uncommon for an architect to require all doors in a corridor to be 20-minute fire rated doors, even if the corridor walls are not fire rated. In situations like this, the doors would be required to be positive latching from two different code references: 1) Because the door is a fire rated door and section 126.96.36.199 requires it to comply with NFPA 80 which requires positive latching; but also 2) Because corridor doors are required to latch, according to section 188.8.131.52.5. However, all of the other NFPA 80 requirements concerning fire rated doors (i.e. self-closing door and fire rated frames) applies since section 184.108.40.206 requires features of life safety that are obvious to the public to be maintained even if they are not required.
If the double egress corridor doors are required to be fire rated, then they too must positively latch. But not all double egress doors in a corridor are required to be fire rated. Double egress doors that serve a smoke compartment barrier are not required to latch, according to section 18/220.127.116.11.
In regards to public restroom doors: According to section 18.104.22.168.6, exception #1, these doors are not required to latch, provided they are not fire-rated doors. It is quite rare to find an entrance door to a restroom that is fire rated.