Where there is no floor assembly above->open air exit?

[sunyaer]

This is from Ontario Building Code Division B Part 9:
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9.9.4.2. Fire Separation for Exits
(1) Except as provided in Sentence (5) and Article 9.9.8.5., every exit other than an exit doorway shall be separated
from each adjacent floor area or from another exit by a fire separation having a fire-resistance rating not less than that
required for the floor assembly above the floor area.

(2) Where there is no floor assembly above, the fire-resistance rating required in Sentence (1) shall not be less than that
required by Subsection 9.10.8. for the floor assembly below, but in no case shall the fire-resistance rating be less than
45 min.
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What kind of situations would "there is no floor assembly above" for an exit? Would this situation be a scenario where the exit is open-air?

 

[tmurray]

This is to ensure there is protection for structural members supporting the roof. Typically, this would be dealing with exit enclosures, like stairwells.

Exterior exit passageways are a little different and may not require fire rating if the conditions of 9.9.4.2.(5) are met.