3.1.6.16 — Exposed Construction Materials and Components in Concealed Spaces

(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) Except as provided in Sentences (3) to (6), Sentence 3.1.6.3. (4), Articles 3.1.6.7. and 3.1.6.12. and Sentences 3.1.6.16. (2) and 3.1.6.17. (2), the exposed surfaces of structural mass timber elements conforming to Article 3.1.6.3. shall be protected from adjacent spaces in the building, including adjacent concealed spaces within wall, floor and roof assemblies, by a material or assembly of materials conforming to Sentence (2) that provides an encapsulation rating of not less than 50 min. (2) Except as provided in Sentence 3.1.6.11. (1), the material or assembly of materials referred to Sentence (1) shall consist of, (a) gypsum board, (b) gypsum concrete, (c) noncombustible materials, (d) materials that conform to Sentences 3.1.5.1. (2) to (4), or (e) any combination of materials listed in Clauses (a) to (d). (3) Except as provided in Sentence (5), the exposed surfaces of mass timber beams, columns and arches within a suite or fire compartment need not be protected in accordance with Sentence (1), provided, (a) the aggregate surface area does not exceed 10% of the total wall area of the perimeter of the suite or fire compartment in which they are located, and (b) the flame-spread rating on any exposed surface is not more than 150. (4) Except as provided in Sentences (5) and (6), the exposed surfaces of mass timber walls within a suite need not be protected in accordance with Sentence (1), provided, (a) each exposed surface faces the same direction, and (b) the flame-spread rating on any exposed surface is not more than 150. (5) The aggregate exposed surface area of mass timber elements within a suite permitted in Sentences (3) and (4) shall not exceed 35% of the total wall area of the perimeter of the suite. (6) The exposed surfaces of mass timber ceilings within a suite need not be protected in accordance with Sentence (1), provided the aggregate area of the exposed surfaces does not exceed, (a) 10% of the total ceiling area of the suite, where the exposed surfaces have a flame-spread rating not more than 150, or (b) 25% of the total ceiling area of the suite, where, (i) the suite contains no mass timber walls with exposed surfaces, and (ii) the exposed surfaces of the mass timber ceiling have a flame-spread rating not more than 75.