Adhesives installed to resist air passage at qualifying mass timber interfaces must comply with ASTM D3498. Therefore, option C is correct. IBC Section 703.7 applies this requirement to Types IV-A, IV-B, and IV-C at prescribed abutting edges and intersections of building elements that require fire-resistance ratings.
ASTM D3498 addresses adhesives used for field-gluing wood-based structural components. Compliance is significant because the adhesive must retain adequate bond performance under the environmental and service conditions associated with the approved application. The special inspector should verify product identification, compatibility with the timber substrate, manufacturer instructions, storage conditions, shelf life, surface preparation, application temperature, coverage, and curing.
UL 263 is a fire-resistance test standard for building assemblies and structural elements; it is not the product standard for the adhesive. ASTM A653 applies to metallic-coated steel sheet. ASTM F1575 concerns pressure-sensitive safety glazing films and is unrelated to sealing mass timber interfaces.
Where the adhesive is required by Section 703.7, its installation is subject to periodic special inspection under Section 1705.20 unless the applicable code exception removes the sealing requirement.
References/Topics: 2021 IBC Sections 703.7 and 1705.20; ASTM D3498; Type IV-C sealing requirements.
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