3.2.6.2.

(1) Except as permitted in Sentence 3.2.6.6.(2)v1, a building to which this Subsection applies shall be designed in accordance with Sentences (2) to (4) and Articles 3.2.6.3.v1 to 3.2.6.7.v1 to limit the danger to occupants and fire fighters from exposure to smoke in a building fire.

(2) Except as provided in Articles 3.2.6.4.v1 to 3.2.6.6.v1, a building referred to in Sentence (1), shall be designed so that, during a period of 2 h after the start of a fire, all floor areas that are above the lowest exit storey will not contain more than 1% by volume of contaminated air from the fire floor, assuming an outdoor temperature equal to the January design temperature on a 2.5% basis determined in conformance with Supplementary Standard SB-1.

(3) Except as provided in Articles 3.2.6.4v1 and 3.2.6.6.v1, a building referred to in Sentence (1), shall be designed so that during a period of 2 h after the start of a fire, the limit described in Sentence (2) on the movement of contaminated air into other floor areas is not exceeded in,

(a) each exit stair serving storeys above the lowest exit level, and

(b) each exit stair serving storeys below the lowest exit level.

(4) Except as provided in Articles 3.2.6.4.v1 and 3.2.6.6.v1, a building referred to in Sentence (1), shall be designed so that during a period of 2 h after the start of a fire, the limit described in Sentence (2) on the movement of contaminated air into other floor areas is not exceeded in a shaft that contains an elevator for use by fire fighters required by Article 3.2.6.9.v1