Free Practice Questions for the International Code Council Special Inspector 93-Tall-Mass-Timber-Buildings Exam (2026 Updated)

The 2 × 2 block is intended to protect the abutting wood edges from the effects of char contraction. Therefore, option D is correct.

During fire exposure, wood chars and the char layer can shrink or contract. At an interface between two abutting timber components, that contraction can create a gap that allows heat and flames to penetrate deeper than predicted for a continuous exposed surface. AWC connection-fire-design methodology therefore requires additional protection at susceptible joints and interfaces. The block shields the abutting edges and maintains the sacrificial wood-cover path around the protected connection.

Its primary function is not decorative, nor is it simply an air-sealing component. Although limiting airflow can be a secondary consequence of closing the interface, the design purpose addressed by the technical guidance is control of premature fire penetration caused by char contraction. The block also should not be interpreted independently as a generic one-hour protective membrane for the steel ledger; the connection’s total rating depends on the complete approved protection assembly.

The inspector should confirm the block’s dimensions, species or product designation, fastening, continuity, and tight installation before the connection is concealed.

References/Topics: AWC Technical Report 10; AWC Fire Design Specification provisions addressing char contraction and gaps between abutting wood members.

The illustrated configuration represents Type IV-C construction , so option C is correct. The distinguishing feature is the combination of noncombustible protection on the exterior face with an exposed CLT surface toward the interior.

IBC Section 602.4.3.1 requires the exterior side of combustible exterior walls in Type IV-C construction to have noncombustible protection providing a minimum assigned time of 40 minutes . Table 722.7.1(2) assigns exactly 40 minutes to one layer of 5/8-inch Type X gypsum board, matching the protection illustrated in Figure 66.

The decisive distinction is Section 602.4.3.2: mass timber elements in Type IV-C are permitted to be unprotected on the interior . This is fundamentally different from Type IV-A, where essentially all interior mass timber faces must be protected, and Type IV-B, where interior protection is generally required but limited areas may remain exposed under specific area and separation restrictions.

Type IV-HT does not use the Type IV-C protected-exterior/exposed-interior regulatory scheme.

References/Topics: 2021 IBC Sections 602.4.3, 602.4.3.1 and 602.4.3.2; Table 722.7.1(2), 5/8-inch Type X gypsum board = 40 minutes.

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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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The illustrated wall corresponds to Type IV-A construction , making option A correct. The key indicator is the extensive Type X gypsum protection provided on the interior face of the CLT wall. Figure 63 shows multiple layers of 5/8-inch Type X gypsum board protecting the interior mass timber, together with the required exterior-side protection.

Type IV-A is the most comprehensively protected of the three tall mass timber construction classifications. IBC Section 602.4.1.2 requires the interior faces of all mass timber elements , including the inside face of exterior mass timber walls, to be protected with qualifying noncombustible material. Section 602.4.1.2.1 requires the protection contribution to satisfy Table 722.7.1(1) and never be less than 80 minutes. Type IV-A exterior walls also require at least 40 minutes of noncombustible protection on the outside face.

The three interior layers shown are consistent with a heavily protected Type IV-A rated wall. By contrast, Type IV-B permits limited exposed interior mass timber, while Type IV-C expressly permits mass timber interior elements to remain unprotected. Type IV-HT operates under fundamentally different heavy-timber provisions.

References/Topics: 2021 IBC Sections 602.4.1.1, 602.4.1.2 and 602.4.1.2.1; Tables 601 and 722.7.1(1)-(2).

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IBC Table 601 requires both exterior and interior bearing walls in Type IV-C construction to have a minimum two-hour fire-resistance rating. Option B is correct.

For exterior bearing walls, the Table 601 rating is not the only applicable criterion. Section 602.1 also requires exterior walls to satisfy Table 705.5 based on occupancy and fire separation distance. Where Table 705.5 or another provision imposes a more restrictive rating, the higher requirement governs.

The two-hour rating may be achieved through the calculated structural fire resistance of the mass timber, approved noncombustible protection, or an approved combination of the two. Connections, intersections, penetrations, and abutting edges must not create a premature failure path or compromise the rated assembly.

A one-hour reduction can be permitted for bearing walls supporting a roof only under Table 601, Footnote “a,” but that exception does not apply to a wall carrying floors or other qualifying structural loads. The inspector must confirm the actual load path before accepting any reduced protection at the uppermost level.

References/Topics: 2021 IBC Sections 601, 602.1 and 602.4; Tables 601 and 705.5; Type IV-C bearing walls.

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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Option D directly reflects the engineering-analysis method authorized by 2021 IBC Section 2304.10.1. For structural connections in Type IV-A, IV-B, or IV-C construction, the analysis must demonstrate that temperatures at every relevant portion of the connection remain within prescribed limits for a period corresponding to the fire-resistance rating required of the connected structural element.

The code establishes two critical temperature-rise limits: an average rise of not more than 250°F and a maximum rise of not more than 325°F . For this purpose, the “connection” includes the connectors, fasteners, and those portions of the wood members that participate structurally in the connection.

Option A is incorrect because ASTM E136 is a test for determining whether a material is noncombustible; it is not the fire-resistance test method for a structural connection. Option B is not a code-recognized substitute for the required connection fire evaluation. Option C is insufficient because a manufacturer’s generalized fire-performance representation does not establish the required code fire-resistance duration unless supported through an approved test, evaluation, or engineering analysis.

References/Topics: 2021 IBC Section 2304.10.1; engineering-analysis method for Type IV-A, IV-B, and IV-C structural connections.

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IBC Table 601 requires floor construction and associated secondary structural members in Types IV-A, IV-B, and IV-C construction to have a two-hour fire-resistance rating. Therefore, option B is correct.

This requirement applies to the complete floor assembly, not only the timber panel. The required two-hour performance may be established through the calculated fire resistance of the mass timber, the contribution of approved noncombustible protection, or a permitted combination of both. Any topping, protective membrane, connection protection, and edge condition that forms part of the approved rated design must be installed accordingly.

The ratings for other building elements should not be transferred to the floor. A three-hour rating applies to the primary structural frame and bearing walls of Type IV-A, but its floor construction remains two hours. Type IV-B and Type IV-C floors also require two hours, even though those construction types permit different degrees of exposed mass timber.

The special inspector must verify panel dimensions, approved layup, protection layers, joints, penetrations, connections, topping thickness, and other details that influence the floor’s rated performance.

References/Topics: 2021 IBC Sections 601 and 602.4; Table 601, floor construction and associated secondary structural members.

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The minimum required fire flow is 500 gallons per minute. Therefore, option C is correct.

Under 2021 IFC Section 3313.2, an approved water supply must be available when combustible building materials for the building under construction are delivered to the project site. The hydrant supplying the required flow must be located within the prescribed distance of the combustible materials as measured along an approved fire apparatus access route. Where one hydrant cannot provide coverage to all combustible material locations, additional hydrants are required.

The 500-gpm requirement is the initial minimum associated with the delivery of combustible building materials. It should not be confused with the potentially greater fire-flow requirements applicable after vertical construction of a Type III, IV, or V building begins. Depending on fire separation distance and the building’s calculated final fire-flow demand, a larger supply may be required under subsequent provisions.

Options A and B provide inadequate suppression capacity. Option D is not the baseline amount prescribed for the condition stated in the question. Inspectors and site safety personnel should verify that the water source is operational and accessible before substantial quantities of mass timber arrive on-site.

References/Topics: 2021 IFC Sections 3313.1 and 3313.2; construction-site water supply and combustible building materials.

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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.

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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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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The figure depicts an unprotected portion of the mass timber ceiling . For Type IV-B construction, Section 602.4.2.2.2, Exception 1.1, limits unprotected ceiling areas—including attached mass timber beams—to 20 percent of the floor area of the applicable dwelling unit or fire area. Option B is therefore correct.

The percentage is based on floor area rather than total ceiling surface area. For example, where the associated fire area contains 1,000 square feet of floor area, the maximum ceiling exposure permitted under this particular exception would be 200 square feet, subject to the additional separation and mixed-exposure provisions.

The 40-percent value in option D applies to mass timber walls, including attached columns , rather than ceilings. The 15-percent and 30-percent values are not the prescribed Type IV-B ceiling exposure limitations in the 2021 IBC.

The inspector must additionally determine whether another exposed wall or ceiling region exists nearby. Section 602.4.2.2.4 imposes a 15-foot separation requirement, and Section 602.4.2.2.3 controls situations where both wall and ceiling surfaces are intentionally exposed.

References/Topics: 2021 IBC Sections 602.4.2.2.2 through 602.4.2.2.4; Type IV-B ceiling exposure limitations.

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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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For the illustrated two-layer protection system, the 5/8-inch Type X gypsum-board layer directly adjacent to the connection is assigned 20 minutes, while the second layer is assigned 40 minutes. Therefore, option C is correct.

The standard assigned protection time for one layer of 5/8-inch Type X gypsum board is 40 minutes. However, the thermal-separation methodology applies a 0.50 reduction factor to the final or base Type X layer located directly against the protected connection. That layer therefore contributes 20 minutes. The outer layer retains its full 40-minute assigned value, producing a combined assigned protection time of 60 minutes for the two-layer configuration.

The layers are not interchangeable for calculation purposes because the reduced contribution applies specifically to the layer adjacent to the protected connection. Options A and B incorrectly assign the same value to both layers, while option D reverses the required allocation.

During inspection, the special inspector should verify layer sequencing, board thickness and type, fastening, joint staggering, edge support, protection at corners, and continuity around the connection. Missing or incorrectly sequenced layers can invalidate the calculated thermal-separation time.

References/Topics: AWC Technical Report 10; AWC 2021 Fire Design Specification Section 3.5.2.1; assigned protection time for Type X gypsum board.

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A sealant required to resist air passage between qualifying mass timber elements must comply with ASTM C920. Therefore, option C is correct. ASTM C920 is the recognized specification for elastomeric joint sealants and establishes requirements for properties such as movement capability, adhesion, cohesion, hardness, weathering, and durability.

IBC Section 703.7 differentiates between the two materials: sealants must meet ASTM C920, while adhesives must meet ASTM D3498. Option D therefore applies to an adhesive rather than a sealant. ASTM E119 is the standard fire test used to establish the fire-resistance rating of structural members and assemblies; it does not serve as the product specification for the sealant. ASTM E114 is not the applicable standard under this provision.

The stated exception is important. Section 703.7 does not require an additional sealant or adhesive where it is not a required component of the tested fire-resistance-rated assembly. Where the approved assembly or code provision does require it, however, the specified product, location, joint preparation, backing material, depth, width, and tooling must match the approved construction documents.

References/Topics: 2021 IBC Section 703.7; ASTM C920 sealants; ASTM D3498 adhesives; tested fire-resistance-rated assemblies.

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The required minimum rating is two hours. Under 2021 IBC Table 601, the primary structural frame in Type IV-C construction must provide a two-hour fire-resistance rating. A structural connection joining members of that frame cannot be permitted to fail before the members it connects; consequently, the connection must remain functional for the same required period.

The protection requirement applies to the complete connection assembly. This includes steel plates, hangers, bolts, screws, dowels, fasteners, welds, bearing regions, and portions of the connected timber that form part of the connection. Compliance can be achieved through tested construction, calculated wood cover, Type X gypsum protection, another approved noncombustible system, or a combination documented by the registered design professional.

Option A is insufficient because it would leave a one-hour weakness in a two-hour structural load path. Option B similarly falls short of the required Table 601 rating. Option D is the Type IV-A primary-frame rating and is not required for the stated Type IV-C condition.

The special inspector must verify protective-cover dimensions and installation before connection hardware becomes concealed, including any project-specific inspection required for calculated wood-cover protection.

References/Topics: 2021 IBC Table 601 and Section 2304.10.1; AWC Fire Design Specification, protection of structural connections.

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The 2021 IFC specifically requires standpipes to be provided in accordance with Section 3313 for Type IV-A, IV-B, and IV-C buildings designed to exceed six stories above grade plane. Therefore, option A is correct.

The code also requires a water supply for fire department operations, but it must be approved by the fire code official and fire chief; it is not described as a mandatory “portable water supply.” This makes option B inaccurate. Where noncombustible protection is required, at least one layer—not two layers—must be installed on applicable building elements more than four levels below active mass timber construction before additional levels are erected. Option D therefore overstates the number of layers.

Required exterior wall coverings must similarly be installed more than four levels below active mass timber construction. Option C incorrectly substitutes two levels for the prescribed four-level threshold.

These provisions limit the amount of unprotected combustible construction exposed at one time and provide the fire department with usable suppression infrastructure as erection progresses. Inspection coordination should verify standpipe extension, hose-connection accessibility, water availability, the progression of passive protection, and exterior-wall covering installation.

References/Topics: 2021 IFC Section 3308.4 and Section 3313; fire safety during construction of tall mass timber buildings.

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Option A correctly applies the protection requirements for mass timber used in qualifying interior exit and elevator hoistway enclosures. Where a two-hour, or 120-minute, fire-resistance rating is required, the noncombustible protection must contribute not less than two-thirds of that required rating. Two-thirds of 120 minutes is 80 minutes.

The 2021 IBC provisions for Type IV-A require interior mass timber surfaces to be protected with compliant noncombustible materials. The assigned protection time is determined under Section 722.7 and cannot be less than the applicable minimum. Option B is incorrect because 40 minutes would provide only one-third of a two-hour rating; Type IV-B protected mass timber generally requires at least 80 minutes for a two-hour element. Option C does not correctly describe the special protection path applicable to mass timber exit and hoistway enclosures. Option D is also incorrect because Type IV-HT is not governed by the tall mass timber enclosure provision stated in the question.

The inspector must verify the total assigned protection time, membrane type, number of layers, fastening, joints, corners, penetrations, and continuity on both required faces of the enclosure.

References/Topics: 2021 IBC Sections 602.4, 602.4.1.2 and 722.7.1; protection of mass timber shaft and exit enclosures.

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Adhesive anchors installed horizontally to resist sustained tension loads require continuous special inspection. Therefore, option D is correct.

Continuous special inspection means that the special inspector must be present during the performance of the regulated work. This heightened oversight is necessary because horizontal or upwardly inclined adhesive-anchor installations resisting sustained tension are sensitive to installation variables such as borehole cleaning, adhesive proportioning, mixing, placement, embedment depth, temperature, cure time, and prevention of adhesive loss before curing. A concealed installation defect can substantially reduce long-term tension capacity.

The other listed activities are generally subject to periodic inspection under the mass timber special-inspection provisions. Periodic inspection allows the inspector to observe the work intermittently at appropriate stages rather than remaining present throughout the entire operation. Bolted connections, concealed mass timber connections, and anchorage of mass timber construction to deep foundation systems must still be inspected, but the code does not automatically designate each of those activities as continuous.

The inspector should also verify installer certification where required, approved adhesive-anchor evaluation documentation, expiration dates, storage conditions, drilling method, hole dimensions, and compliance with the approved structural documents.

References/Topics: 2021 IBC Sections 1705.3 and 1705.5.3; Table 1705.3; continuous inspection of adhesive anchors under sustained tension.

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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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