1.3.3.4.Building Size Determination

(1) Where a firewall divides a building, each portion of the building that is divided shall be considered as a separate building, except for the purposes of (a) a determination of gross area in Section 1.2. of Division C, (b) a fire alarm and detection system in Sentence 3.2.4.2.(1) of Division B or Article 9.10.18.1. of Division B, and (c) a plumbing system interconnected through a firewall. (2) Except as permitted in Sentence (3), where portions of a building are completely separated by a vertical fire separation that has a fire-resistance rating of not less than 1 h and extends through all storeys and service spaces of the separated portions, each separated portion is permitted to be considered as a separate building for the purpose of determining building height, provided (a) each separated portion is not more than 3 storeys in building height and is used only for residential occupancies other than a retirement home, and (b) the unobstructed path of travel for a firefighter from the nearest street to one entrance of each separated portion is not more than 45 m. (See Note A-1.3.3.4.(2)) (3) The vertical fire separation referred to in Sentence (2) may terminate at the floor assembly immediately above a basement provided the basement conforms to Article 3.2.1.2. of Division B.