International Code Council Updated 93-Tall-Mass-Timber-Buildings Exam Questions and Answers by claire

Option B is correct because the required protection time placed over a mass timber structural connection may be established through a code-recognized fire-resistance evaluation of that protective construction under standard fire exposure.

IBC Section 2304.10.1 regulates connections in Types IV-A, IV-B, and IV-C. The code allows connection fire performance to be demonstrated through testing where the connection is incorporated into the fire-resistance test or through an approved engineering analysis. AWC further clarifies that the protection applied over the connection must provide the necessary protection time and that its performance may be established using the methods recognized by IBC Section 703.3, including testing and engineering analysis based on ASTM E119 or UL 263 performance.

Option A is too narrow: testing an isolated fastener does not establish the fire protection of the entire connection. Options C and D also use the wrong temperature location. Where an engineering-analysis route is used, the temperature criterion applies to the connection itself , including connectors, fasteners, and portions of wood incorporated into the structural connection—not simply to the protected structural element or supported member.

References/Topics: 2021 IBC Section 2304.10.1; Section 703.3; AWC guidance on fire resistance of mass timber connections.

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The 1/2-inch lag screws attaching the structural steel ledger require fire protection, making option D correct. These fasteners are structural components of the ledger-to-CLT connection and therefore form part of the connection whose fire performance must be maintained for the required duration.

AWC Technical Report 10 states that wood structural connections—including their connectors, fasteners, and participating members—must be protected from fire exposure for the required fire-resistance time . Protection may be provided by wood cover, fire-rated gypsum board, other approved materials, or a combination.

TR10 distinguishes structural connection fasteners from small fasteners used merely to hold sacrificial protection in place. The report specifically explains that fasteners attaching protective wood strips need not themselves be protected, provided they are sufficiently long to keep the protection in position throughout the required exposure.

In the illustrated ledger connection, the 1/2-inch lag screws transfer structural load between the steel ledger and CLT wall. Their thermal protection is therefore integral to maintaining connection capacity.

References/Topics: AWC Technical Report No. 10 Sections 4.5 and connection examples; thermal protection of structural connectors and fasteners.

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Option D is the incorrect statement. IBC Section 722.7.2.1 requires the panel edges of the face layer , rather than the base layer, to be taped and finished with joint compound. Fastener heads on the face layer must also be covered with joint compound.

The other three provisions accurately reproduce the code. Each gypsum-board layer must be secured with Type S drywall screws long enough to penetrate the mass timber at least 1 inch when driven flush. Screws for the base layer are installed at 12 inches on center in both directions . Subsequent layers use the same general spacing but are offset from screws in the preceding layer. In addition, the panel edges of each succeeding layer must be offset 18 inches from the panel edges of the previous layer.

These details are not merely workmanship recommendations. They form part of the installation conditions under which the protection contributions in Table 722.7.1(2) can be credited.

References/Topics: 2021 IBC Section 722.7.2.1, Items 1–9; fastening, panel-edge offset, and finishing of Type X gypsum protection.

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Type IV-HT construction permits concealed spaces where those spaces comply with the specific protection alternatives prescribed for traditional heavy-timber construction. One permitted method is to completely fill the concealed space with noncombustible insulation. Therefore, option D is correct.

This provision should not be confused with the concealed-space requirements applicable to the tall mass timber classifications—Types IV-A, IV-B, and IV-C. Those classifications employ dedicated noncombustible protection and assigned-time requirements intended to control the contribution of concealed combustible construction during a fire. Type IV-HT follows a different concealed-space framework and allows protection through approved alternatives, including sprinkler protection, gypsum-board enclosure, or complete filling with noncombustible insulation, as applicable.

The insulation must completely occupy the concealed volume. Merely installing partial batt insulation, leaving unprotected voids, or relying on nominally fire-resistant thermal insulation does not satisfy the provision. The inspector should verify the material’s noncombustibility, continuity, placement around obstructions, and conformance with the approved construction documents before the space becomes inaccessible.

References/Topics: 2021 IBC Section 602.4.4; concealed spaces in Type IV-HT construction; noncombustible insulation protection method.

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