Free Practice Questions for International Code Council 93-Tall-Mass-Timber-Buildings Exam

Option D most accurately characterizes Type IV-B under the 2021 IBC. The default rule is that interior faces of mass timber elements—including the inside face of exterior mass timber walls and mass timber roofs—receive noncombustible protection. However, Section 602.4.2.2.2 permits specifically limited portions of walls and ceilings to remain exposed.

That combination of extensive protection plus controlled exposure is the defining practical distinction between Types IV-A, IV-B, and IV-C. Type IV-A requires essentially complete interior protection of mass timber surfaces. Type IV-B uses substantial noncombustible protection but permits limited exposed wall and ceiling areas under quantitative and separation restrictions. Type IV-C, by contrast, permits mass timber interior elements to remain unprotected generally, while retaining special requirements for exterior walls, concealed spaces, and shaft enclosures.

Option A therefore more closely describes the protection philosophy of Type IV-A. Option B invents a 50-percent rule that does not exist in the 2021 IBC. Option C more closely resembles the broad exposure philosophy of Type IV-C, though even that wording oversimplifies its specific requirements.

References/Topics: 2021 IBC Sections 602.4.1, 602.4.2 and 602.4.3; Type IV-A, IV-B and IV-C protection concepts.

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ASTM E84 cannot be used to establish the hourly fire-resistance rating of a structural member or assembly. Therefore, option B is correct.

ASTM E84 evaluates surface-burning characteristics , principally flame-spread and smoke-developed indices. Those measurements characterize how a material ' s exposed surface behaves when subjected to the standard tunnel test. They do not demonstrate that a wall, floor, roof, beam, column, or structural assembly will maintain integrity and structural performance for one, two, or three hours.

Fire-resistance ratings are instead established through the methods recognized by the IBC, including standard fire testing—principally ASTM E119 or UL 263—prescriptive rated construction provided by Section 721, and calculated fire-resistance procedures under Section 722. The code also recognizes appropriately documented approved designs and other approved methods within the Section 703 framework.

This distinction is particularly important in mass timber work because ASTM E84 may appear elsewhere in the code for flame-spread limitations on materials, but an acceptable E84 result does not establish structural fire endurance.

The special inspector must determine which approved fire-resistance methodology applies and verify that the installed assembly precisely reflects that design.

References/Topics: 2021 IBC Sections 703, 721 and 722; ASTM E119; UL 263; distinction between fire resistance and ASTM E84 surface-burning testing.

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Option C is not an IFC requirement. The 2021 IFC requires inspection records to be maintained on-site, but it does not require those records to be secured in a fire- and water-resistant safe.

Section 3303.2 requires the owner to designate a site safety director. Section 3303.3 then makes that director responsible for completing a daily fire safety inspection of the project site. Every day, building and outdoor construction areas must be evaluated against the prescribed fire-safety inspection items.

The results of each inspection must be documented and retained on-site until a certificate of occupancy has been issued . The records must also be immediately available at the site for presentation to the fire code official upon request. Options A, B, and D therefore accurately reflect the code requirements.

The daily inspection program covers practical hazards such as hot work, temporary heating, combustible debris, temporary electrical wiring, hazardous-material storage, fire apparatus access, hydrants, fire department connections, standpipe availability, and portable extinguishers.

For tall mass timber projects, this documentation is particularly important because substantial combustible construction may be present before permanent fire protection systems are complete.

References/Topics: 2021 IFC Sections 3303.2 and 3303.3; site safety director; daily fire-safety inspection and documentation.

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A 7/16-inch wood structural panel is not one of the prescriptively acceptable fireblocking materials listed by IBC Section 718.2.1. Therefore, option C is correct.

Section 718.2.1 permits fireblocking to consist of several specified materials. These include one-half-inch gypsum board; properly secured batts or blankets of mineral wool, mineral fiber, or other approved materials; and mass timber complying with Section 2304.11. Options A, B, and D are consequently valid.

For wood structural panels, however, the IBC requires a substantially greater thickness: a single thickness of approximately 0.719 inch , conventionally represented as 23/32 inch, with joints backed by material of the same required thickness. A 7/16-inch panel is only approximately 0.438 inch thick and therefore does not satisfy that prescriptive fireblocking provision.

Fireblocking is intended to interrupt concealed draft openings and restrict the movement of flame and hot gases through concealed combustible spaces. It should not be confused with a tested firestop system used at penetrations through fire-resistance-rated assemblies.

Special inspection should confirm that the installed material, thickness, joint backing, retention, and location conform to the approved construction documents and the applicable code provision.

References/Topics: 2021 IBC Sections 718.2 and 718.2.1; Section 2304.11; permitted fireblocking materials.

The required minimum wood protection thickness is 1.75 inches , making option B correct. AWC Technical Report No. 10 establishes a thermal-separation methodology for protecting steel connectors and fasteners with sacrificial wood cover. Because the question specifies that the wood cover itself must provide the entire 60-minute fire-protection period, the protection thickness must be calculated using the thermal-separation provisions rather than relying on residual fire resistance from the connector or steel plate.

TR10 applies a reduction to the protection contribution of the base wood layer. Its connection examples use the relationship in Section 4.4.1.3, with the required thermal protection time divided by 0.85. For a 60-minute requirement, back-calculating the prescribed nonlinear wood charring equation gives approximately 1.71 inches of required wood thickness. The practical minimum corresponding to the available choices is therefore 1.75 inches.

The principle is critical for special inspection: steel connection components have high thermal conductivity and must remain below the temperature limits assumed by the connection fire design. The inspector must verify actual wood-cover thickness, fastening, continuity, and any gaps before concealment.

References/Topics: AWC Technical Report No. 10, Sections 4.4.1.3 and 4.5; connection thermal separation; wood protection of steel connectors. TR10 demonstrates the same calculation methodology for wood-covered steel connections.

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A separate inspection by the building official is required where the fire resistance of a structural connection in Type IV-A, IV-B, or IV-C construction is provided by wood cover calculated in accordance with Section 2304.10.1. Therefore, option C is correct.

The required inspection occurs after the calculated wood cover has been installed but before additional coverings or finishes conceal the connection. This sequencing allows the building official to verify the actual cover thickness, geometry, continuity, fit, fastening, and correspondence with the approved fire-resistance design.

The requirement is distinct from routine Chapter 17 special inspection. Although a qualified special inspector may observe connection installation and mass timber erection, Section 110.3.5 expressly identifies a required building-department inspection for this calculated wood-cover condition. The inspection cannot be bypassed merely because the connection was observed during structural installation.

A rated joint system under Section 715 is governed by its tested or listed assembly requirements but is not the circumstance identified by this specific inspection provision. The other options do not state the code trigger. Inspectors should therefore coordinate notification before the connection is enclosed because subsequent destructive exposure may otherwise be necessary.

References/Topics: 2021 IBC Sections 110.3.5 and 2304.10.1; inspection of calculated wood cover protecting mass timber connections.

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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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In Type IV-C construction, combustible construction forming concealed spaces must receive noncombustible protection providing an assigned time of at least 40 minutes. Consequently, option D is correct.

Type IV-C permits substantial portions of mass timber to remain exposed within occupied interior spaces, subject to the applicable construction and fire-resistance requirements. That permission does not extend unchanged into concealed spaces. Concealed combustible surfaces create a different hazard because fire can spread above ceilings, inside shafts, or within service cavities without immediate detection. Section 602.4.3.5 therefore imposes a specific 40-minute noncombustible protection requirement.

An NFPA 13 sprinkler system is generally required for tall mass timber buildings, but sprinkler protection alone is not the prescribed substitute for this concealed-space protection. Fire-retardant-treated wood is still combustible and does not constitute the required noncombustible protective membrane. Option C is also incorrect because the concealed-space rule is more specific than the provisions governing exposed surfaces in occupied spaces.

Inspection should occur before closure so that membrane continuity, board orientation, fastener spacing, joint treatment, penetrations, and protection around connection hardware can be fully observed.

References/Topics: 2021 IBC Sections 602.4.3.2 and 602.4.3.5; Table 722.7.1(1); concealed combustible construction in Type IV-C buildings.

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IBC Table 722.7.1(2) assigns a 40-minute protection contribution to 5/8-inch Type X gypsum board . Therefore, option D is correct.

The same table assigns 25 minutes to 1/2-inch Type X gypsum board. Consequently, option B overstates the protection contribution of the thinner Type X panel. Ordinary gypsum board values appearing elsewhere in Section 722 cannot simply be substituted for the specific mass timber noncombustible protection values in Table 722.7.1(2). Options A and C therefore do not state the protection contribution recognized by the mass timber table.

These assigned values are particularly important when multiple layers are required. For example, a two-hour building element requires at least 80 minutes of noncombustible protection under Table 722.7.1(1), which can be satisfied prescriptively with two properly installed layers of 5/8-inch Type X gypsum board, each contributing 40 minutes.

The contribution is valid only when the gypsum board is installed and fastened in accordance with Section 722.7.2.

References/Topics: 2021 IBC Tables 722.7.1(1) and 722.7.1(2); Section 722.7.2; Type X gypsum noncombustible protection.

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Under the illustrated connection detail, the minimum wood-block dimensions are 3 inches by 3 inches. Therefore, option C is correct.

The block is part of the sacrificial wood-cover system used to protect the connection for the full two-hour fire-resistance period. It must provide sufficient timber beyond the protected connection region to account for calculated charring and the increased exposure that can develop at the interface between abutting wood members. Because the problem states that the CLT-to-glulam bearing area is already the minimum required, the primary members do not provide surplus material that can be credited as additional protection at that edge.

AWC connection-fire-design guidance requires the protective geometry to remain effective after the calculated char front advances. Char contraction can open a gap at abutting edges and expose material deeper in the connection than would occur on an uninterrupted planar surface. The 3-inch-by-3-inch block maintains the required protective envelope for the stated two-hour condition.

This dimension is specific to the illustrated configuration and assumptions; it is not a universal minimum for every mass timber connection. The inspector must verify the approved detail rather than substitute nominal blocking based solely on field availability.

References/Topics: AWC Technical Report 10; AWC Fire Design Specification provisions for wood-cover protection and char contraction at abutting members.

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