Prefabricated wood I-joists are engineered wood framing products, but they are not mass timber elements because their configuration does not meet the minimum solid cross-sectional dimensions required for Type IV mass timber construction. Option B is therefore correct.
An I-joist consists of relatively thin flanges connected by a thin structural web. Its efficient open- web-like cross section is fundamentally different from a large solid, laminated, built-up or panelized timber element. I-joists are separately regulated by IBC Section 2303.1.2 and are manufactured and evaluated in accordance with ASTM D5055.
Solid-sawn lumber can qualify as mass timber when it satisfies the minimum heavy-timber dimensions. Structural glued-laminated timber is a recognized large-section engineered timber product, while cross-laminated timber is explicitly recognized as a panelized mass timber product and is regulated by ANSI/APA PRG 320.
The critical inspection point is that the term “engineered wood” does not automatically mean “mass timber.” The special inspector must verify the product category, minimum dimensions, approved construction type, applicable product standard, identification marks and installation requirements shown in the approved construction documents.
References/Topics: 2021 IBC Chapter 2 definition of “Mass Timber”; Sections 2303.1.2, 2303.1.3, 2303.1.4 and 2304.11; ASTM D5055.
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