(1) Except as otherwise provided in this Subsection and Articles 3.2.2.16. and 3.2.3.19., a building or part of a building permitted to be of encapsulated mass timber construction is permitted to include structural mass timber elements, including beams, columns, arches and wall, floor and roof assemblies, provided they comply with Sentences (2) and (3).
(2) Structural mass timber elements referred to in Sentence (1) shall,
(a) except as provided in Sentence (4), be arranged in heavy solid masses containing no concealed spaces,
(b) have essentially smooth flat surfaces with no thin sections or sharp projections, and
(c) except as provided in Sentence 3.1.6.17. (1), conform to the minimum dimensions stated in Table 3.1.6.3.
(3) Adhesives used in structural mass timber elements referred to in Sentence (1) that are constructed of cross-laminated timber shall conform to the elevated temperature performance requirements in ANSI/APA PRG 320, “Standard for Performance-Rated Cross-Laminated Timber”.
(4) Concealed spaces are permitted within structural mass timber elements referred to in Sentence (2) and need not conform to Sentence 3.1.6.4. (1) provided the concealed spaces are,
(a) sprinklered and divided into compartments by fire blocks in conformance with Subsection 3.1.11.,
(b) completely filled with rocks or slag fibre insulation conforming to CAN/ULC-S702.1 “Standard for Mineral Fibre Thermal Insulation for Buildings, Part 1: Material Specification” and having a density not less than 32 kg/m3,
(c) if horizontal, lined with not less than a single layer of 12.7 mm thick Type X gypsum board or noncombustible material providing an encapsulation rating of not less than 25 min, or
(d) if vertical, lined with not less than a single layer of 12.7 mm thick Type X gypsum board or noncombustible material providing an encapsulation rating of not less than 25 min and vertically divided into compartments by fire blocks in conformance with Subsection 3.1.11.