3.1.11.3 — Fire Blocks between Nailing and Supporting Elements

(1) Except as permitted by Sentences (2) to (4) and (7) fire blocks shall remain in place and prevent the passage of flames for not less than 15 min when subjected to the standard fire exposure in CAN/ULC-S101, “Fire Endurance Tests of Building Construction and Materials”. (2) Gypsum board not less than 12.7 mm thick and sheet steel not less than 0.38 mm thick need not be tested in conformance with Sentence (1) provided all joints have continuous support. (3) In a building required to be of noncombustible construction, wood nailing elements described in Article 3.1.5.6. need not be tested in conformance with Sentence (1). (3.1) In a building or part of a building permitted to be of encapsulated mass timber construction, wood nailing elements referred to in Article 3.1.6.11. need not be tested in conformance with Sentence (1). (4) In a building permitted to be of combustible construction, in a combustible roof system permitted by Sentences 3.1.5.3. (2) and 3.1.6.7. (1), and in a raised platform permitted by Sentence 3.1.5.8. (2) or 3.1.6.12. (1), fire blocks are permitted to be, (a) solid lumber or a structural composite lumber product conforming to ASTM D5456, “Evaluation of Structural Composite Lumber Products”, not less than 38 mm thick, (b) phenolic bonded plywood, OSB or waferboard not less than 12.5 mm thick with joints supported, or (c) two thicknesses of lumber or a structural composite lumber product conforming to ASTM D5456, “Evaluation of Structural Composite Lumber Products”, each not less than 19 mm thick with joints staggered, where the width or height of the concealed space requires more than one piece of lumber or structural composite lumber product not less than 38 mm thick to block off the space. (5) Openings through fire blocks shall be protected to maintain the integrity of the construction. (6) Where fire blocks are penetrated by construction elements or by service equipment, a fire stop shall be used to seal the penetration. (7) In a building permitted to be of combustible construction, semi-rigid fibre insulation board, produced from glass, rock or slag, is permitted to be used to block the vertical space in a double wythe wall assembly formed at the intersection of the floor assembly and the walls, provided the insulation board, (a) has a density not less than 45 kg/m3, (b) is securely fastened to one set of studs, (c) extends from below the bottom of the top plates in the lower storey to above the top of the bottom plate in the upper storey, and (d) completely fills the portion of the vertical space between the headers and between the wall plates.

(1) Combustible stage flooring supported on noncombustible structural members is permitted in a building required to be of noncombustible construction. (2) Wood members more than 50 mm but not more than 375 mm high applied directly to or set into a noncombustible floor slab are permitted for the construction of a raised platform in a building required to be of noncombustible construction provided the concealed spaces created are divided into compartments by fire blocks in conformance with Sentence 3.1.11.3. (2). (3) The floor system for the raised platform referred to in Sentence (2) is permitted to include combustible subfloor and combustible finished flooring. (4) Combustible finished flooring is permitted in a building required to be of noncombustible construction.

(1) Wood members that are more than 50 mm but not more than 300 mm high are permitted to be used for the construction of a raised platform in a building or part of a building permitted to be of encapsulated mass timber construction, and they need not conform to Articles 3.1.6.3. and 3.1.6.4., provided, (a) the concealed spaces created by the wood members are divided into compartments by fire blocks in conformance with Sentence 3.1.11.3. (4), and (b) the wood members are, (i) applied directly to or set into a noncombustible floor slab, or (ii) applied directly to a mass timber floor assembly that conforms to the requirements of Article 3.1.6.3. (2) The upper surface of the mass timber floor assembly referred to in Subclause (1)(b)(ii) is permitted to be encapsulated only between the wood members by a material or assembly of materials conforming to Sentences 3.1.6.4. (1) and (2). (3) The floor system for the raised platform referred to in Sentence (1) is permitted to include a combustible subfloor and combustible finished flooring.