3.1.5.5.

(1) Except for an exposing building face required to conform to Sentence 3.2.3.7.(1) or Sentence 3.2.3.7.(4), an exterior non-loadbearing wall assembly that includes combustible components is permitted to be used 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) not more than 6 storeys in building height if sprinklered,

(b) the interior surfaces of the wall assembly are protected by a thermal barrier conforming to Sentence 3.1.5.11.(3), and

(c) the wall assembly satisfies the criteria of Sentences (2) and (3) when subjected to testing in conformance with CAN/ULC-S134, “Fire Test of Exterior Wall Assemblies”.

(2) Flaming on or in the wall assembly shall not spread more than 5 m above the opening during the test procedure referenced in Sentence (1).

(3) The heat flux during the flame exposure on a wall assembly shall be not more than 35 kW/m² measured 3.5 m above the opening during the test procedure referenced in Sentence (1).

(4) 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, “Accelerated Weathering on Fire-Retardant-Treated Wood for Fire Testing”.

(5) The requirements in this Article do not apply where foamed plastic insulation is used in an exterior wall assembly of a building and the insulation is protected in conformance with Sentences 3.2.3.8.(1) and (2).