The Ontario Building Code | Twenty-Minute Closures

3.1.8.10. Twenty-Minute Closures

(1) A door assembly having a fire-protection ratingnot less than 20 min is permitted to be used as a closurein,

(a) a fire separation not required to have a fire-resistance rating more than 1 h, located between,

(i) a public corridor and a suite,

(ii) a corridor and adjacent sleeping rooms, or

(iii) a corridor and adjacent classrooms, offices and libraries in Group A, Division 2 major occupancies, or

(b) a fire separation not required to have a fire-resistance rating more than 45 min, located in a buildingnot more than 3 storeys in building height.

(2) The requirements for noncombustiblesills and combustible floor coverings in NFPA 80, "Fire Doors and Other Opening Protectives", do not apply to a door described in Sentence (1).

(3) A door described in Sentence (1) shall have a clearance not more than 6 mm at the bottom and not more than 3 mm at the sides and top.

(4) In elementary and secondary schools, a door assembly conforming to Articles 9.10.13.2. and 9.10.13.3. is permitted to be used as a closure in a fire separationhaving a fire-resistance rating of 30 min.