Free and Premium International Code Council 93-Tall-Mass-Timber-Buildings Dumps Questions Answers

ANSI/APA PRG 320 is the governing product standard for performance-rated cross-laminated timber, including adhesive qualification, bond integrity, manufacturing quality control, and required product identification. Accordingly, option D is correct.

Bond-line performance is critical because CLT panels depend on structural adhesive to transfer shear forces between laminations and maintain composite action. PRG 320 establishes qualification and quality-assurance requirements intended to verify that adhesive bonds remain structurally reliable and resist delamination or inadequate bond development. Testing and manufacturing controls under this standard address the completed CLT product rather than treating the adhesive as an isolated material.

AITC 113 concerns dimensional tolerances and related requirements for structural glued-laminated timber rather than CLT bond-line shear qualification. ASTM C557 addresses adhesives for ceramic tile and is unrelated to structural timber manufacture. ANSI 117 is not the governing CLT manufacturing standard.

During inspection, the special inspector ordinarily does not reproduce factory bond-line tests on-site. Instead, the inspector verifies the CLT manufacturer’s identification, certification marks, panel grade, layup designation, and conformance with PRG 320 and the approved construction documents.

References/Topics: 2021 IBC Section 2303.1.4; ANSI/APA PRG 320; CLT adhesive-bond qualification and manufacturing quality assurance.

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Option A reproduces one of the two permitted exterior gypsum-board fastening methods in 2021 IBC Section 722.7.2.2. Type X gypsum board used as noncombustible protection on the exterior side of mass timber walls may be attached using galvanized nails of minimum 12 gage with a 7/16-inch head and sufficient length to penetrate the mass timber at least 1 inch .

The code also permits ASTM C1002 Type S, W, or G screws, but those screws must likewise penetrate the mass timber a minimum of 1 inch . Options C and D are therefore incorrect because they specify only 3/4-inch and 7/8-inch penetration, respectively. Option B is incorrect because it substitutes 16-gage nails for the minimum 12-gage requirement.

Section 722.7.2.2 additionally requires exterior Type X gypsum-board layers to be fastened 12 inches on center each way and 6 inches on center at joints or ends. Panel-edge fasteners must be located at least 1 inch and not more than 2 inches from the edge.

These fastening details are part of the conditions necessary to claim the protection contribution in Table 722.7.1(2).

References/Topics: 2021 IBC Sections 722.7.1 and 722.7.2.2; exterior Type X gypsum-board protection.

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The required separation is 15 feet , making option B correct. Section 602.4.2.2.4 of the 2021 IBC specifically regulates the separation distance between unprotected mass timber elements in Type IV-B construction.

Within each dwelling unit or fire area, unprotected portions of mass timber walls and ceilings must be separated from other unprotected wall and ceiling portions by not less than 15 feet . For ceiling-related surfaces, the separation is measured horizontally along the ceiling. For wall-to-wall exposure, the applicable separation is measured horizontally along the floor.

This requirement operates in addition to the maximum exposed-area restrictions. A designer therefore cannot merely demonstrate that the exposed ceiling is below 20 percent or that exposed walls are below 40 percent of floor area; the exposed regions must also satisfy the required spatial separation.

The purpose is to prevent multiple exposed mass timber regions from acting as closely spaced fuel packages during a compartment fire. During inspection, dimensions should be checked against the approved documents before required gypsum or other noncombustible protection is completed.

References/Topics: 2021 IBC Section 602.4.2.2.4; separation distance between unprotected Type IV-B mass timber elements.

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ASTM E84 is not a test for establishing the fire-resistance rating of a structural member or building assembly. Therefore, option B is the exception.

The 2021 IBC establishes fire-resistance ratings primarily through testing conducted in accordance with ASTM E119 or UL 263. Those tests evaluate whether an element or assembly can maintain structural performance, limit flame passage, and control temperature rise for a specified duration under standardized fire exposure. ASTM E84 instead evaluates surface-burning characteristics, principally flame-spread and smoke-developed indices. An E84 classification cannot establish that a wall, floor, beam, column, or connection possesses a one-, two-, or three-hour fire-resistance rating.

The IBC also recognizes approved prescriptive designs under Section 721, calculated fire resistance under Section 722, and designs documented in approved sources or supported by permitted analytical methods. Those are valid methods represented by options A, C, and D.

For inspection purposes, the approved construction documents must identify the method used to establish the rating. The inspector must then verify that the installed materials, dimensions, loading assumptions, protective layers, fasteners, joints, and connection details match the tested, calculated, or prescriptive design.

References/Topics: 2021 IBC Sections 703.2, 703.2.1, 721 and 722; ASTM E119 and UL 263 fire-resistance testing.

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The connection detail specifies the CLT-to-glulam screws at 24 inches on center , so option D is correct. This is a construction-document interpretation question rather than a universal prescriptive screw-spacing requirement imposed by the IBC.

The approved structural detail controls the required spacing for this particular connection because the registered design professional has established the connection geometry and fastener schedule based on the applicable structural loads, CLT panel configuration, glulam member, fastener properties, and required load transfer. The 24-inch dimension must therefore be maintained in the field unless an approved revision changes the connection design.

IBC Table 1705.5.3 is directly relevant to the special inspector’s responsibilities. For screws used in Type IV-A, IV-B, or IV-C mass timber connections, periodic special inspection includes verification of diameter, length, head type, spacing, installation angle, and installation depth . The special inspector is therefore expected to compare actual field installation against precisely this type of approved connection detail.

Substituting 12-, 16-, or 20-inch spacing without design authorization would constitute a deviation from the approved documents, even if the alternate spacing appeared more conservative.

References/Topics: Approved structural connection detail shown in the exhibit; 2021 IBC Section 1705.5.3 and Table 1705.5.3, inspection of screw spacing and installation.

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ICC-ES ESR-1539 is the applicable evaluation report, making option C correct. ESR-1539 addresses nails and staples manufactured by participating companies and evaluates their use in engineered and nonengineered structural connections.

An ICC-ES Evaluation Report provides evidence that a proprietary product or system complies with specified building-code requirements where the product does not rely solely on the generic prescriptive provisions of the IBC. For proprietary nails, the report provides the technical basis needed to establish characteristics such as dimensions, materials, recognized structural applications, allowable design values, installation limitations, and conditions of use.

The current ICC-ES document is published as ESR-1539P, reflecting subsequent administrative updates to the report, but the identifying evaluation-report number remains 1539 , matching option C and the examination question.

For special inspection, merely recognizing the ESR number is not enough. The inspector should verify that the installed proprietary fastener is actually included in the report, that its diameter and length correspond to the approved construction documents, and that installation spacing, penetration, orientation, substrate, and other report conditions are satisfied.

References/Topics: ICC-ES ESR-1539, structural nails and staples; proprietary fastener evaluation and installation requirements. ICC-ES states that the nails and staples covered by ESR-1539 are used in engineered and prescriptive structural connections.

ASTM C920 is the required standard for sealants used under the IBC mass timber air-sealing provision. Option C is therefore correct. Section 703.7 applies to Type IV-A construction and requires compliant sealant or adhesive at specified interfaces involving fire-resistance-rated mass timber elements.

The sealing requirement reduces the movement of air, heat, and combustion gases into gaps that could expose additional timber surfaces and undermine the rated performance assumed by the approved design. The sealant must not merely appear to close the opening; it must be the specified product and installed within its approved joint dimensions and substrate conditions.

ASTM A36 is a structural steel material specification. ASTM E119 establishes procedures for fire testing building construction and assemblies but does not qualify elastomeric sealant products. ASTM F1667 covers driven fasteners such as nails, spikes, and staples and has no application to this sealing requirement.

Under Section 1705.20, installation is subject to periodic special inspection where the Section 703.7 sealant is applied. Inspection should occur before concealment and confirm continuity, adhesion, backing, joint depth, surface cleanliness, and compliance with the approved documents.

References/Topics: 2021 IBC Sections 703.7 and 1705.20; Type IV-A construction; ASTM C920.

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IBC Section 722.7 establishes the governing calculation principle for protected mass timber. The required fire resistance consists of the inherent fire resistance of the unprotected mass timber element plus the protection time contributed by the noncombustible protection . Therefore, option D is correct.

This approach recognizes two sequential protective mechanisms. First, the noncombustible covering delays heating and charring of the timber. After the credited protection period, the remaining mass timber cross section provides structural fire resistance through predictable charring behavior and residual section capacity. Section 722.7.1 further requires the contribution of the covering material to comply with the prescribed protection times or to be established under Section 703.6.

Option A ignores the contribution of the protective membrane. Option B ignores the inherent structural fire resistance of the timber. Option C incorrectly substitutes a finish rating for the code-recognized protection contribution. A finish rating is a separate temperature-based performance concept and is not automatically additive as the protection time used by Section 722.7.

References/Topics: 2021 IBC Sections 602.4, 703.6, 722.7 and 722.7.1; calculation of protected mass timber fire resistance.

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Mass timber can be incorporated into all five principal IBC construction types, although the extent and permitted application vary substantially. Therefore, option D is the technically complete answer.

Types III, IV and V provide the broadest opportunities for mass timber structural systems. Type III permits combustible interior building elements, Type IV is specifically organized around mass timber or noncombustible structural elements, and Type V permits structural elements of any material allowed by the code. Type IV includes the tall mass timber classifications IV-A, IV-B and IV-C, together with Type IV-HT.

Types I and II are predominantly noncombustible construction, but they are not absolute prohibitions against every wood or mass timber application. IBC Section 603 identifies permitted combustible materials in Types I and II. In addition, Table 601, Note c, permits heavy timber complying with Section 2304.11 for roof construction—including applicable primary structural frame members—where the required fire-resistance rating is one hour or less.

Consequently, the answer does not mean that a Type I or Type II building may be framed entirely with exposed mass timber. It means that code-compliant mass timber elements can be used in defined applications within each construction type.

References/Topics: 2021 IBC Sections 602.1–602.5 and 603.1; Table 601, Note c; Section 2304.11.

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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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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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A proprietary field-glued mass timber beam splice requires special inspection because the connection relies on a field-applied adhesive process that is not covered as a routine prescriptive mass timber connection in Table 1705.5.3. The controlling mechanism is IBC Section 1705.1.1, which authorizes the building official to require special inspection for unusual materials, systems, or installation procedures, particularly where compliance depends on additional manufacturer installation instructions.

The ICC code-development rationale for the tall mass timber provisions specifically identifies field-glued mass timber beam or panel splices as an example of work for which special inspection can be required. Inspection must address the approved evaluation report and manufacturer’s instructions, including substrate preparation, moisture and temperature limits, adhesive storage and expiration, mixing or proportioning, application quantity, open time, member alignment, clamping or pressure, and curing conditions.

Approval by the permit applicant has no regulatory significance. Verification by the registered design professional may supplement the inspection program but does not replace the approved special inspector. A building official may observe the work, but routine field verification by that official is not the prescribed quality-control procedure.

References/Topics: 2021 IBC Sections 1704.2, 1704.3 and 1705.1.1; special cases; proprietary field-glued mass timber splices.

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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.

A conventional 2 × 6 solid-sawn stud is a light-frame member and does not satisfy the minimum cross-sectional dimensions associated with mass timber or heavy-timber construction. Therefore, option A is the exception.

The IBC defines mass timber as Type IV structural elements primarily composed of solid, built-up, panelized or engineered wood products that meet the minimum cross-sectional dimensions required for Type IV construction. A nominal 2 × 6 stud is substantially smaller than those dimensions and is ordinarily classified as conventional light-frame construction. Its use might be permitted in a particular nonstructural partition or another specifically authorized application, but it is not itself a qualifying mass timber structural element.

CLT is expressly recognized as a mass timber panel product. Parallel-strand lumber is a form of structural composite lumber and can qualify where it satisfies the applicable minimum dimensions, product-standard requirements and approved structural design. Dowel-laminated timber is a built-up panelized timber product and may likewise serve as a mass timber element when its dimensions, engineering and approval satisfy the construction documents and code.

The classification depends on the completed element’s dimensions and approved structural function—not merely on the fact that it is manufactured from wood.

References/Topics: 2021 IBC Chapter 2 definitions of “Mass Timber” and “Conventional Light-Frame Construction”; Sections 602.4 and 2304.11.

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Option A correctly reflects the required noncombustible protection for protected Type IV-A mass timber. Under IBC Section 602.4.1.2.1, the noncombustible protection applied to interior faces of Type IV-A mass timber must contribute the protection time determined by the applicable provisions of Section 722.7, but not less than 80 minutes .

The broader Type IV provisions are particularly important for interior exit and elevator hoistway enclosures. In qualifying tall mass timber buildings with an occupied floor more than 75 feet above the lowest level of fire department access, mass timber interior exit and elevator hoistway enclosures are permitted up to the specified height limits only where protected in accordance with Section 602.4.1.2. For a two-hour, 120-minute-rated enclosure, at least 80 minutes must therefore come from the prescribed noncombustible protection.

Type IV-B likewise uses an 80-minute minimum for protected interior mass timber, so option B ' s 40-minute value is incorrect. Type IV-C has different exposure allowances and shaft-protection provisions, but option C does not state the controlling tall-building enclosure requirement tested here. Type IV-HT is not governed by the Type IV-A tall mass timber enclosure protection rule.

References/Topics: 2021 IBC Sections 602.4 and 602.4.1.2 through 602.4.1.2.1; Section 722.7.

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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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Minimum prescriptive dimensions are not themselves a component added into a calculated fire-resistance time. Therefore, option A is the exception.

IBC Section 602.4 states that a mass timber element’s required fire resistance can be based on the fire-resistance contribution of the mass timber, the noncombustible protection, or a combination of those two components. Options B, C, and D reflect those permitted approaches.

Minimum dimensions under Section 2304.11 serve a different function. They establish the minimum cross-sectional size and construction characteristics required for qualifying heavy timber or mass timber elements. A member can satisfy the minimum dimensional requirement without automatically achieving every required one-, two-, or three-hour fire-resistance rating. The structural fire calculation must evaluate the remaining effective section after charring, elevated-temperature effects, applied loading, and any credited protective materials.

The inspector must therefore verify both requirements independently: the installed member must meet the minimum code dimensions and must match the approved fire-resistance design. Increasing a member to the minimum prescriptive size does not by itself replace the required calculation, tested assembly, or approved protection system.

References/Topics: 2021 IBC Sections 602.4, 703.2, 722.7 and 2304.11; calculated mass timber fire resistance.

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Concealed connections in Type IV-C construction require periodic special inspection under 2021 IBC Table 1705.5.3, making option B correct.

The mass timber special-inspection table specifically applies to mass timber elements in Types IV-A, IV-B, and IV-C . Among the activities listed for periodic inspection are bolted connections, concealed connections, erection of mass timber construction, screw installation, verification of required predrilling, and several other connection-related installation characteristics.

Options A and C are incorrect because they specify Type IV-HT. Table 1705.5.3 is expressly scoped to Types IV-A, IV-B, and IV-C rather than Type IV-HT. Option D involves a listed Type IV-A activity, but its inspection frequency is wrong: adhesive anchors installed horizontally or upwardly inclined to resist sustained tension loads require continuous , not periodic, special inspection.

For concealed connections, inspection must occur while the relevant components remain observable. Once CLT panels, wood cover, gypsum protection, or finishes hide the connection, critical installation details may no longer be verifiable without destructive removal.

References/Topics: 2021 IBC Section 1705.5.3 and Table 1705.5.3, Required Special Inspections of Mass Timber Construction.

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The prescribed proportion is two-thirds , making option C correct. The relationship is demonstrated directly by IBC Table 722.7.1(1). A building element requiring a one-hour fire-resistance rating must receive 40 minutes of noncombustible protection; a two-hour element requires 80 minutes; and a three-hour-or-greater element requires 120 minutes. Each of those prescribed values represents two-thirds of the corresponding one-, two-, or three-hour rating.

For Type IV-A specifically, Section 602.4.1.2 requires protection of the interior faces of all mass timber elements. Section 602.4.1.2.1 further states that the protection must contribute at least the time assigned in Table 722.7.1(1) and not less than 80 minutes .

The remaining portion of the required fire resistance is provided by the mass timber element itself. Thus, for a three-hour Type IV-A primary structural element, 120 minutes are provided through noncombustible protection and the timber must supply the remaining required endurance.

This two-component approach is fundamental to the Type IV-A fire-design methodology.

References/Topics: 2021 IBC Sections 602.4.1.2 and 602.4.1.2.1; Tables 601 and 722.7.1(1); protected Type IV-A mass timber.

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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 structural connections must maintain a fire-resistance rating corresponding to the required rating of the structural elements they connect. Because both the glulam beam and CLT panels require a two-hour fire-resistance rating, their connections must also provide two hours of fire resistance. Therefore, option C is correct.

Concealing steel hardware inside a timber member does not eliminate the fire-resistance requirement. Steel rapidly conducts heat and can lose strength, while timber surrounding a concealed connector can char, split, or withdraw from fasteners. The connection must consequently be protected through sufficient wood cover, noncombustible protection, tested assemblies, or an approved engineering analysis demonstrating acceptable connection temperatures and capacity for the entire required duration.

A three-hour rating is not required merely as a generalized safety factor; the code requires correspondence with the connected elements unless the approved design establishes another condition. A one-hour connection would create a premature weak point in the load path, and a zero-hour rating would be unacceptable simply because the hardware is hidden.

References/Topics: 2021 IBC Section 2304.10.1; fire-resistance rating of mass timber connections; protected concealed steel hardware.

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The permitted reduction is one hour. Table 601 assigns a two-hour base fire-resistance rating to exterior and interior bearing walls in Type IV-C construction. Footnote “a” to the table permits the ratings of the primary structural frame and bearing walls to be reduced by one hour where those elements support a roof only.

Accordingly, a Type IV-C bearing wall that supports only roof construction may be assigned a one-hour rating after application of the permitted reduction. The allowance recognizes that the element is not carrying occupied floor levels above and therefore presents a lower consequence of progressive structural failure than a wall supporting one or more floors.

The reduction is not automatic merely because a bearing wall is located at the upper story. The approved structural documents must establish that the wall supports only the roof and does not carry floor loads, transfer loads, elevated mechanical platforms, occupied rooftop structures, or other construction that invalidates the condition.

Options A and B are not reductions specified by Table 601. Option D would eliminate the entire two-hour rating and is not permitted. The inspector should verify the applicable rating and the precise load path before accepting reduced fire protection at the top story.

References/Topics: 2021 IBC Table 601, Footnote “a”; Type IV-C bearing walls and roof-support rating reduction.

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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 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.