The construction detail identifies a 1/2-inch tolerance between the steel beam web and the adjacent CLT panel. Therefore, option B is correct.

This is principally a construction-document interpretation question rather than a generic prescriptive IBC dimension. The 2021 IBC does not establish one universal steel-web-to-CLT clearance applicable to every mass timber connection. The required clearance is project specific and is established by the registered design professional through the approved structural drawings and connection details.

The tolerance provides erection clearance for placement of the prefabricated CLT around the steel member while accounting for fabrication and installation variation. It must not be arbitrarily reduced or increased because the gap can affect panel fit, bearing conditions, fastener alignment, fire-protection continuity, acoustic treatment and any specified joint-filling material.

Under the special-inspection framework, the inspector must compare the installed connection directly with the approved construction documents. Any condition that does not maintain the specified 1/2-inch clearance—or any undocumented field modification to the CLT or steel connection—must be reported and resolved through the registered design professional rather than accepted solely on the contractor’s direction.

References/Topics: Approved structural details; 2021 IBC Sections 1704.2 and 1705.5; inspection of mass timber erection, anchorage and connections.