3.1.5.5.Combustible Cladding on Exterior Walls

(1) Except as provided in Sentences (2) and (3), combustible cladding is permitted to be used on an exterior wall assembly in a building required to be of noncombustible construction, provided (a) the building is (i) not more than 3 storeys in building height, or (ii) sprinklered throughout, and (b) except as provided in Sentence (4), when tested in accordance with CAN/ULC-S134, “Standard Method of Fire Test of Exterior Wall Assemblies,” the wall assembly satisfies the following criteria for testing and conditions of acceptance: (See Note A-3.1.5.5.(1)(b)) (i) flaming on or in the wall assembly does not spread more than 5 m above the opening, and (See Note A- 3.1.5.5.(1)(b)(i)) (ii) the heat flux during the flame exposure on the wall assembly is not more than 35 kW/m measured at 3.5 m above the opening. (See Note A-3.1.5.5.(1)(b)(ii)) (2) Except as permitted by Articles 3.2.3.10. and 3.2.3.11., where the limiting distance in Tables 3.2.3.1.-B to 3.2.3.1.-E permits an area of unprotected openings of not more than 10% of the exposing building face, the construction requirements of Table 3.2.3.7. shall be met. (3) A wall assembly permitted by Sentence (1) that includes combustible cladding of fire-retardant-treated wood shall be tested for fire exposure after the cladding has been subjected to an accelerated weathering test as specified in ASTM D2898, “Standard Practice for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing.” (4) Exterior wall assemblies constructed in accordance with Section 6 of MMAH Supplementary Standard SB-2, “Fire Performance Ratings” are deemed to comply with Clause (1)(b).