3.1.14.

(1) If a fire-retardant treated wood roof system is used to comply with the requirements of Subsection 3.2.2., the roof deck assembly shall meet the conditions of acceptance of CAN/ULC-S126-M, “Test for Fire Spread Under Roof-Deck Assemblies”.

(2) Supports for the roof deck assembly referred to in Sentence (1) shall consist of,

(a) fire-retardant treated wood,

(b) heavy timber construction,

(c) noncombustible construction, or

(d) a combination of the items described in Clauses (a), (b) and (c).

(1) Except as permitted by Sentence (2), a metal roof deck assembly shall meet the conditions of acceptance of CAN/ULC-S126-M, “Test for Fire Spread Under Roof-Deck Assemblies”, if,

(a) it supports a combustible material above the deck that could propagate a fire beneath the roof deck assembly, and

(b) the deck is used to comply with the requirements of Sentences 3.2.2.25.(2), 3.2.2.32.(2), 3.2.2.53.(2), 3.2.2.59.(2), 3.2.2.69.(2), and 3.2.2.76.(2) for noncombustible construction.

(2) The requirements of Sentence (1) are waived provided,

(a) the combustible material above the roof deck is protected by not less than 12.7 mm thick gypsum board, mechanically fastened to a supporting assembly if located beneath the roof deck, or by a thermal barrier conforming to one of Clauses 3.1.5.12.(2)(c)v1v2 to (e) that is located,

(i) on the underside of the combustible material, or

(ii) beneath the roof deck,

(b) the building is sprinklered, or

(c) the roof assembly has a fire-resistance rating not less than 45 min.