What seismic detailing and lateral force-resisting system requirements apply?

Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:

• CBC § 8-706 High relevance — show source text

  SECTION 8-706 — LATERAL LOAD REGULATIONS

  8-706.1 Seismic forces. Strength-level seismic forces used to evaluate the structure for resistance to seismic loads shall be based on the R -values tabulated in the regular code for similar lateral-force-resisting systems including consideration of the structural detailing of the members where such R -values exist. Where such R -values do not exist, an appropriate R -value shall be rationally assigned considering the structural detailing of the members.

  Exceptions:

  1. The forces need not exceed 0.75 times the seismic forces prescribed by the regular code requirements.
  2. For Risk Category I, II or III structures, near-fault increases in ground motion (maximum considered earthquake ground motion of 0.2 second spectral response greater than 150 percent at 5 percent damping) need not be considered when the fundamental period of the building is 0.5 seconds in the direction under consideration.
  3. For Risk Category I or II structures, the seismic base shear need not exceed 0.30W.
  4. For Risk Category III or IV structures, the seismic base shear need not exceed 0.40W.

  8-706.1.1 When a building is to be strengthened with the addition of a new lateral force resisting system, the R -value of the new system can be used when the new lateral force resisting system resists at least 75 percent of the building’s base shear regardless of its relative rigidity.

  8-706.1.2 Evaluation and seismic improvement of unreinforced masonry bearing wall buildings shall comply with the California Existing Building Code (CEBC), Appendix Chapter A1 2013 Edition, and as modified by the CHBC.

  Exceptions:

  1. Alternative standards may be used on a case-by-case basis when approved by the authority having jurisdiction. It shall be permitted to exceed the strength limitation of 100 psi in Section A108.2 of the CEBC when test data and building configuration supports higher values subject to the approval of the authority having jurisdiction.
  2. CEBC Section A102.2 shall not apply to Qualified Historical Buildings in Risk Category III buildings and other structures whose primary occupancies are public assembly with an occupancy load greater than 300.

  8-706.1.3 All deviations from the detailing provisions of the lateral-force-resisting systems shall be evaluated for stability and the ability to maintain load-carrying capacity at the expected inelastic deformations.

  8-706.2 Existing building performance. The seismic resistance may be based upon the ultimate capacity of the structure to perform, giving due consideration to ductility and reserve strength of the lateral-force-resisting system and materials while maintaining a reasonable factor of safety. Broad judgment may be exercised regarding the strength and performance of materials not recognized by regular code requirements. (See Chapter 8-8, Archaic Materials and Methods of Construction.)

  8-706.2.1 All structural materials or members that do not comply with detailing and proportioning requirements of the regular code shall be evaluated for potential seismic performance and the consequence of non-compliance. All members that would be reasonably expected to fail and lead to collapse or life threatening injury when subjected to seismic demands shall be judged unacceptable, and appropriate structural strengthening shall be developed.

  8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.

• CBC § 4.09 High relevance — show source text

  For anchorage of concrete or masonry walls to roof and floor diaphragms, the out-of-plane strength design force shall not be less than 280 lb/linear ft (4.09 kN/m) of wall. Required anchors in masonry walls of hollow units or cavity walls shall be embedded in a reinforced grouted structural element of the wall. See Sections 1609 for wind design requirements and 1613 A for earthquake design requirements. 1604 A .8.3 Decks. Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:

  1. The reactions resulting from the dead load and live load specified in Table 1607 A .1, or the snow load specified in Section 1608, in accordance with Section 1605 A, acting on all portions of the deck.
  2. The reactions resulting from the dead load and live load specified in Table 1607 A .1, or the snow load specified in Section 1608 A, in accordance with Section 1605 A, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604 A .9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

  Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

  1604 A .10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

  2025 CALIFORNIA BUILDING CODE 16A-9

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  STRUCTURAL DESIGN

  SECTION 1605 A —LOAD COMBINATIONS

  1605 A .1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605 A .2. Exceptions:

• CBC § 3114.8.4.2 High relevance — show source text

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  SPECIAL CONSTRUCTION

  3114.8.4.2 Seismic design parameters. The seismic force-resisting system shall be designed and detailed in accordance with ASCE 7 and one of the following:

  1. Where all or portions of the profiled steel panel elements are considered to be the seismic force-resisting system, design and detailing shall be in accordance with the AISI S100 and ASCE 7, Table 12.2-1 requirements for steel systems not specifically detailed for seismic resistance, excluding cantilever column systems. [DSA-SS & DSA-SS/CC] Not permitted by DSA.

  2. Where all or portions of the profiled steel panel elements are not considered to be part of the seismic force-resisting system, an independent seismic force-resisting system shall be selected and detailed in accordance with ASCE 7, Table 12.2-1.

  3. Where all or portions of the profiled steel panel elements are retained and integrated into a seismic force-resisting system other than as permitted by Item 1, seismic design parameters shall be developed from testing and analysis in accordance with Section 104.2.3 and ASCE 7, Section 12.2.1.1 or 12.2.1.2.

  3114.8.4.3 Allowable shear value. The allowable shear values for the profiled steel panel side walls and end walls shall be determined in accordance with the design approach selected in Section 3114.8.4.2. Where penetrations are made in the side walls or end walls designated as part of the lateral force-resisting system, the penetrations shall be substantiated by rational analysis.

  3114.8.5 Simplified structural design procedure of single-unit containers. Single-unit intermodal shipping containers conforming to the limitations of Section 3114.8.5.1 shall be permitted to be designed in accordance with Sections 3114.8.5.2 and 3114.8.5.3. [DSA-SS & DSA-SS/CC] Not permitted by DSA.

  3114.8.5.1 Limitations. The use of Section 3114.8.5 is subject to the following limitations:

  1. The intermodal shipping container shall be a single-unit, stand-alone unit supported on a foundation and shall not be in contact with or supporting any other shipping container or other structure.

  2. The intermodal shipping container top and bottom rails, corner castings, and columns or any portion thereof shall not be notched, cut, or removed in any manner.

  3. The intermodal shipping container shall be erected in a level and horizontal position with the floor located at the bottom.

  4. The intermodal shipping container shall be located in Seismic Design Category A, B, C or D.

  3114.8.5.2 Structural design assumptions. Where permitted by Section 3114.8.5.1, single-unit, stand-alone intermodal shipping containers shall be designed using the following assumptions for the profile steel panel lateral-force resisting system:

  1. The appropriate detailing requirements contained in Chapters 16 through 23.
  2. Response modification coefficient, R = 2.
  3. Overstrength factor, Ω 0 = 2.5.
  4. Deflection amplification factor, C d = 2.
  5. Limits on structural height, h n = 9.5 feet (2900 mm).

  **3114.8.5.3 Allowable shear.

• CBC § 16A-9 High relevance — show source text

  2. The reactions resulting from the dead load and live load specified in Table 1607 A .1, or the snow load specified in Section 1608 A, in accordance with Section 1605 A, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604 A .9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

  Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

  1604 A .10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

  2025 CALIFORNIA BUILDING CODE 16A-9

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

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  STRUCTURAL DESIGN

  SECTION 1605 A —LOAD COMBINATIONS

  1605 A .1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605 A .2. Exceptions:

  1. The modifications to load combinations of ASCE 7, Section 2.3, ASCE 7, Section 2.4 and Section 1605 A .2 specified in ASCE 7 Chapters 18 and 19 shall apply.

  2. Where the allowable stress design load combinations of ASCE 7, Section 2.4 are used, flat roof snow loads of 45 pounds per square foot (2.15 kN/m [2] ) and roof live loads of 30 pounds per square foot (1.44 kN/m [2] ) or less need not be combined with seismic load. Where flat roof snow loads exceed 45 pounds per square foot (2.15 kN/m [2] ), 15 percent shall be combined with seismic loads.

  3. Where the allowable stress design load combinations of ASCE 7 Section 2.4 are used, crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind loads.

  4. Where design for tornado loads is required, the alternative allowable stress design load combinations of Section 1605 A .2 shall not apply when tornado loads govern the design.

• CBC § 8-705.1 High relevance — show source text

  8-705.1 Gravity loads. The capacity of the structure to resist gravity loads shall be evaluated and the structure strengthened as necessary. The evaluation shall include all parts of the load path. Where no distress is evident, and a complete load path is present, the structure may be assumed adequate by having withstood the test of time if anticipated dead and live loads will not exceed those historically present.

  8-705.2 Wind and seismic loads. The ability of the structure to resist wind and seismic loads shall be evaluated. Wind loads shall be considered when appropriate, but need not exceed 75 percent of the wind loads prescribed by the regular code. The evaluation shall be based on the requirements of Section 8-706.

  8.705.2.1 Any unsafe conditions in the lateral-load-resisting system shall be corrected, or alternative resistance shall be provided. When strengthening is required, additional resistance shall be provided to meet the minimum requirements of the CHBC. The strengthening measures shall be selected with the intent of meeting the performance objectives set forth in Section 8-701.2. The evaluation of structural members and structural systems for seismic loads shall consider the inelastic performance of structural members and their ability to maintain load-carrying capacity during the seismic loadings prescribed by the regular code.

  8.705.2.2 The architect or engineer shall consider additional measures with minimal loss of, and impact to, historical materials which will reduce damage and needed repairs in future earthquakes to better preserve the historical structure in perpetuity. These additional measures shall be presented to the owner for consideration as part of the rehabilitation or restoration.

  2025 CALIFORNIA HISTORICAL BUILDING CODE 13

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  STRUCTURAL REGULATIONS

  SECTION 8-706 — LATERAL LOAD REGULATIONS

  8-706.1 Seismic forces. Strength-level seismic forces used to evaluate the structure for resistance to seismic loads shall be based on the R -values tabulated in the regular code for similar lateral-force-resisting systems including consideration of the structural detailing of the members where such R -values exist. Where such R -values do not exist, an appropriate R -value shall be rationally assigned considering the structural detailing of the members.

  Exceptions:

  1. The forces need not exceed 0.75 times the seismic forces prescribed by the regular code requirements.
  2. For Risk Category I, II or III structures, near-fault increases in ground motion (maximum considered earthquake ground motion of 0.2 second spectral response greater than 150 percent at 5 percent damping) need not be considered when the fundamental period of the building is 0.5 seconds in the direction under consideration.
  3. For Risk Category I or II structures, the seismic base shear need not exceed 0.30W.
  4. For Risk Category III or IV structures, the seismic base shear need not exceed 0.40W.

  8-706.1.1 When a building is to be strengthened with the addition of a new lateral force resisting system, the R -value of the new system can be used when the new lateral force resisting system resists at least 75 percent of the building’s base shear regardless of its relative rigidity.

  8-706.1.2 Evaluation and seismic improvement of unreinforced masonry bearing wall buildings shall comply with the California Existing Building Code (CEBC), Appendix Chapter A1 2013 Edition, and as modified by the CHBC.

  Exceptions:

• CBC § 8-706.1.3 High relevance — show source text

  Exceptions:

  1. Alternative standards may be used on a case-by-case basis when approved by the authority having jurisdiction. It shall be permitted to exceed the strength limitation of 100 psi in Section A108.2 of the CEBC when test data and building configuration supports higher values subject to the approval of the authority having jurisdiction.
  2. CEBC Section A102.2 shall not apply to Qualified Historical Buildings in Risk Category III buildings and other structures whose primary occupancies are public assembly with an occupancy load greater than 300.

  8-706.1.3 All deviations from the detailing provisions of the lateral-force-resisting systems shall be evaluated for stability and the ability to maintain load-carrying capacity at the expected inelastic deformations.

  8-706.2 Existing building performance. The seismic resistance may be based upon the ultimate capacity of the structure to perform, giving due consideration to ductility and reserve strength of the lateral-force-resisting system and materials while maintaining a reasonable factor of safety. Broad judgment may be exercised regarding the strength and performance of materials not recognized by regular code requirements. (See Chapter 8-8, Archaic Materials and Methods of Construction.)

  8-706.2.1 All structural materials or members that do not comply with detailing and proportioning requirements of the regular code shall be evaluated for potential seismic performance and the consequence of non-compliance. All members that would be reasonably expected to fail and lead to collapse or life threatening injury when subjected to seismic demands shall be judged unacceptable, and appropriate structural strengthening shall be developed.

  8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.

  8-706.4 Parapets. Parapets and exterior decoration shall be investigated for conformance with regular code requirements for anchorage and ability to resist prescribed seismic forces.

  An exception to regular code requirements shall be permitted for those parapets and decorations which are judged not to be a hazard to life safety.

  8-706.5 Nonstructural features. Nonstructural features of historical structure, such as exterior veneer, cornices and decorations, which might fall and create a life safety hazard in an earthquake, shall be evaluated. Their ability to resist seismic forces shall be verified, or the feature shall be strengthened with improved anchorage when appropriate.

  8-706.5.1 Partitions and ceilings of corridors and stairways serving an occupant load of 30 or more shall be investigated to determine their ability to remain in place when the building is subjected to earthquake forces.

  8-706.5.2 Seismic forces used to evaluate and improve nonstructural components and their anchorage, where required, shall comply with ASCE 41 or need not exceed 0.75 times the seismic forces prescribed by the requirements of the regular code.

  14 2025 CALIFORNIA HISTORICAL BUILDING CODE

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  8-8 ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION

  SECTION 8-801 — PURPOSE, INTENT AND SCOPE

• CBC § 1705.13.7 High relevance — show source text

  TABLE 1705.13.7—REQUIRED INSPECTIONS OF STORAGE RACK SYSTEMS	Col2	Col3	Col4	Col5
  TYPE	CONTINUOUS INSPECTION	PERIODIC INSPECTION	REFERENCED STANDARD	IBC REFERENCE
  1. Materials used, to verify compliance with one or more of the material test reports in accordance with the approved construction documents.	—	X	—	—
  2. Fabricated storage rack elements.	—	X	—	Section 1704.2.5
  3. Storage rack anchorage installation.	—	X	ANSI/MH16.1 Section 7.3.2	—
  4. Completed storage rack system, to indicate compliance with the approved construction documents.	—	X	—	—

  1705.13.8 Seismic isolation systems. Periodic special inspection shall be provided for seismic isolation systems in seismically isolated structures assigned to Seismic Design Category B, C, D, E or F during the fabrication and installation of isolator units and energy dissipation devices.

  1705.13.9 Cold-formed steel special bolted moment frames. Periodic special inspection shall be provided for the installation of cold-formed steel special bolted moment frames in the seismic force-resisting systems of structures assigned to Seismic Design Category D, E or F.

  1705.14 Testing for seismic resistance. Testing for seismic resistance shall be required as specified in Sections 1705.14.1 through 1705.14.4, unless exempted from special inspections by the exceptions of Section 1704.2.

  1705.14.1 Structural steel. Nondestructive testing for seismic resistance shall be in accordance with Section 1705.14.1.1 or 1705.14.1.2, as applicable.

  1705.14.1.1 Seismic force-resisting systems. Nondestructive testing of structural steel in the seismic force-resisting systems in buildings and structures assigned to Seismic Design Category B, C, D, E or F shall be performed in accordance with the quality assurance requirements of AISC 341. [OSHPD 1R, 2 & 5] and this code.

  Exceptions: [OSHPD 1R, 2 & 5] Not permitted by OSHPD.

  1. In buildings and structures assigned to Seismic Design Category B or C, nondestructive testing is not required for structural steel seismic force-resisting systems where the response modification coefficient, R, designated for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7, Table 12.2-1, has been used for design and detailing.
  2. In structures assigned to Seismic Design Category D, E, or F, nondestructive testing is not required for structural steel seismic force-resisting systems where design and detailing in accordance with AISC 360 is permitted by ASCE 7, Table 15.4-1.
• CBC § 2.1 Medium relevance — show source text

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  STEEL

  1. For members designed based on tension, the slenderness ratio (L/r) shall not exceed 300, except for the design of hangers and bracing in accordance with NFPA 13 and for rod hangers in tension. 2. For members designed based on compression, the slenderness ratio (KL/r) shall not exceed 200, except for the design of hangers and bracing in accordance with NFPA 13.

  2202 A .2 Seismic design. Where required, the seismic design, fabrication and erection of buildings, structures and portions thereof shall be in accordance with Section 2202 A .2.1 or 2202 A .2.2, as applicable.

  2202 A .2.1 Structural steel seismic force-resisting systems and composite structural steel and concrete seismic force- resisting systems. The design, detailing, fabrication and erection of structural steel seismic force-resisting systems and composite structural steel and concrete seismic force-resisting systems shall be in accordance with the provisions of Section 2202 A .2.1.1 or 2202 A .2.1.2, as applicable. Seismic force-resisting systems of structural steel acting compositely with reinforced concrete shall be considered as an alternative system, except as permitted by:

  [DSA-SS] Section 2202A.6.1.

  [OSHPD 1 & 4] Section 2202A.4.1.

  2202 A .2.1.1 Seismic Design Category B or C. Not permitted by DSA-SS and OSHPD.

  2202 A .2.1.2 Seismic Design Category D, E or F. Structures assigned to Seismic Design Category D, E or F shall be designed and detailed in accordance with AISC 341. Beam-to-column moment connections in structural steel special moment frames and intermediate moment frames shall be prequalified in accordance with AISC 341, Section K1, qualified by testing in accordance with AISC 341, Section K2, or shall be prequalified in accordance with AISC 358.

  2202 A .2.2 Structural steel elements. The design, detailing, fabrication and erection of structural steel elements in seismic forceresisting systems, including struts, collectors, chords and foundation elements, shall be in accordance with AISC 341.

  2202A.3 Modifications to AISC 341. [OSHPD 1 and 4]

  2202A.3.1 Section A4. Modify Section A4.1 Item (c) by adding the following:

  (c) Locations and dimensions of protected zones. The fabricator shall permanently mark protected zones of structural elements in the seismic force-resisting system in the building that are designated on the construction documents. If these markings are obscured during construction, such as after the application of fire protection, the owner’s designated representative shall re-mark the protected zones as they are designated on the construction documents. [OSHPD 1 & 4] Primers or paints used to mark protected zones on steel surfaces, which are to receive sprayed fire-resistance material, shall comply with California Building Code Section 704.13.3.2.

• CBC § 1613.2.4 Medium relevance — show source text

  The structure consists of light-frame construction; the design spectral response acceleration at short periods, S DS, as determined in Section 1613.2.4, does not exceed 0.5; and the building height of the structure does not exceed 35 feet (10 668 mm). 2. The seismic force-resisting system of the structure consists of reinforced masonry or reinforced concrete; the design spectral response acceleration at short periods, S DS, as determined in Section 1613.2.4, does not exceed 0.5; and the building height of the structure does not exceed 25 feet (7620 mm). 3. The structure is a detached one- or two-family dwelling not exceeding two stories above grade plane and does not have any of the following horizontal or vertical irregularities in accordance with Section 12.3 of ASCE 7: 3.1. Torsional or extreme torsional irregularity. 3.2. Nonparallel systems irregularity. 3.3. Stiffness-soft story or stiffness-extreme soft story irregularity. 3.4. Discontinuity in lateral strength-weak story irregularity.

  1705.13.1 Structural steel. Special inspections for seismic resistance shall be in accordance with Section 1705.13.1.1 or 1705.13.1.2, as applicable.

  1705.13.1.1 Seismic force-resisting systems. Special inspections of structural steel in the seismic force-resisting systems in buildings and structures assigned to Seismic Design Category B, C, D, E or F shall be performed in accordance with the quality assurance requirements of AISC 341. [OSHPD 1R, 2 & 5] and this code.

  Exceptions: [OSHPD 1R, 2 & 5] Not permitted by OSHPD.

  1. In buildings and structures assigned to Seismic Design Category B or C, special inspections are not required for structural steel seismic force-resisting systems where the response modification coefficient, R, designated for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7, Table 12.2-1, has been used for design and detailing.

  17-14 2025 CALIFORNIA BUILDING CODE

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  SPECIAL INSPECTIONS AND TESTS

  2. In structures assigned to Seismic Design Category D, E, or F, special inspections are not required for structural steel seismic force-resisting systems where design and detailing in accordance with AISC 360 is permitted by ASCE 7, Table 15.4-1.

  1705.13.1.2 Structural steel elements. Special inspections of structural steel elements in the seismic force-resisting systems of buildings and structures assigned to Seismic Design Category B, C, D, E or F other than those covered in Section 1705.13.1.1, including struts, collectors, chords and foundation elements, shall be performed in accordance with the quality assurance requirements of AISC 341. [OSHPD 1R, 2 & 5] and this code.

• CBC § 501A.3 Medium relevance — show source text

  501 A .2 Fire-resistance ratings. Fire-resistance ratings shall comply with the California Building Standards Code.

  501A.3 Prescriptive compliance provisions. Alterations, additions and changes of occupancy to the following categories of existing buildings and structures shall comply with the provisions of this section.

  501A.3.1 Prescriptive compliance provisions for SPC-4D using the California Building Code, 1980 (CBC 1980). Nonconforming buildings shall satisfy the following requirements: 1. The California Building Code, 1980 (CBC 1980), as used in this chapter, consists of the Uniform Building Code, 1979 (UBC 1979) along with requirements contained in: a) California Code of Regulations, Title 24- Building Standards, dated February 2, 1980 (Revision record for Register 80, No. 5). b) California Code of Regulations, Title 22 – Social Security, dated October 13, 1979 (Revision Record for Register 79, No 41). c) California Code of Regulations, Title 17 – Public Health, dated October 13, 1979 (Revision Record for Register 79, No 41-B). 2. All existing structural elements of Seismic Force Resisting System (SFRS) shall satisfy the detailing requirements in the CBC 1980 or demonstrate that the level of seismic performance is equivalent to that given in the CBC 1980, as determined by the building official. 3. A continuous load path or paths with adequate strength and stiffness to transfer all the forces from the point of origin to final point of resistance shall be justified by analysis. 4. Site data report in accordance with the CBC 1980 shall establish that seismically induced differential settlement does not exceed 1 ″ in 40 ′ .

  5. Adjacent buildings shall satisfy the SPC building separation requirements in accordance with the California Administrative Code, Chapter 6 Section 3.4. 6. The addition of new structural elements or strengthening of existing structural elements for retrofit of nonconforming build- ings to SPC-4D shall comply with the following: a) The seismic demand (forces or displacements) shall be in accordance with the CBC 1980; b) Capacity, detailing and connections for new structural elements shall satisfy the requirements in the CBC 2025 for new construction; and c) The strengthening of existing structural elements shall use capacities determined in accordance with the CBC 2025 for new construction consistent with the detailing and connections used in the strengthened member. 7. All construction, quality assurance and quality control shall be in accordance with the new construction provisions of CBC 2025.

  8. Elements not part of the Seismic Force-Resisting System (SFRS), including those identified in the California Administrative Code Chapter 6, Article 10, shall be evaluated using seismic forces and the requirements of the CBC 1980. 9. Any column or wall that forms part of two or more intersecting SFRS and is subjected to axial load due to seismic forces acting along either principal plan axis equaling or exceeding 20 percent of the axial design strength of the column or wall shall be _evaluated for the most critical load effect due to application of seismic force in any direction.

• CBC § 12.3 Medium relevance — show source text

  Stories above the uppermost story with a soft, weak or open-front wall line shall be considered in the analysis but need not be modified. The lateral load-path analysis for added structural elements shall include evaluation of the allowable soil-bearing and lateral pressures in accordance with the building code. Where any portion of a building within the scope of this chapter is constructed on or into a slope steeper than one unit vertical in three units horizontal (33-percent slope), the lateral force-resisting system at and below the base level diaphragm shall be analyzed for the effects of concentrated lateral forces at the base caused by this hillside condition.

  [BS] A403.3 Design base shear and design parameters. The design base shear in a given direction shall be permitted to be 75 percent of the value required for similar new construction in accordance with the building code. The value of R used in the design of the strengthening of any story shall not exceed the lowest value of R used in the same direction at any story above. The system overstrength factor, Ω 0, and the deflection amplification factor, C d, shall be not less than the largest respective value corresponding to the R factor being used in the direction under consideration.

  Exceptions:

  1. For structures assigned to Seismic Design Category B, values of R, Ω 0 and C d shall be permitted to be based on the seismic force-resisting system being used to achieve the required strengthening.

  2025 CALIFORNIA EXISTING BUILDING CODE APPENDIX A-45

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

  2. For structures assigned to Seismic Design Category C or D, values of R, Ω 0 and C d shall be permitted to be based on the seismic force-resisting system being used to achieve the required strengthening, provided that when the strengthening is complete, the strengthened structure will not have an extreme weak story irregularity defined as Type 5b in ASCE 7, Table 12.3-2.

  3. For structures assigned to Seismic Design Category E, values of R, Ω 0 and C d shall be permitted to be based on the seismic force-resisting system being used to achieve the required strengthening, provided that when the strengthening is complete, the strengthened structure will not have an extreme soft story, a weak story, or an extreme weak story irregularity defined, respectively, as Types 1b, 5a and 5b in ASCE 7, Table 12.3-2.

  4. For retrofit systems involving different seismic force-resisting systems in the same direction within the same story, resisting elements are permitted to be designed using the least value of R for the different structural systems found in each independent line of resistance if all of the following conditions are met: 4.1. The building is assigned to Risk Category I or II. 4.2. The building height is no more than four stories above grade plane. 4.3. The seismic force-resisting systems of the retrofitted building comprise only wood structural panel shear walls, steel moment-resisting frames, steel cantilever columns and steel-braced frames. Values for C and Ω 0 shall be consistent with the R value used.

• CBC § 1.10.4.3 Medium relevance — show source text

  1.10.4.3 Identification of amendments. For applications listed in Section 1.10.4, amendments appear in this code preceded with the acronym [OSHPD 4], unless the entire chapter is applicable.

  1.10.4.4 Reference to other chapters. Where reference is made within this code to sections in Chapters 16, 17, 18, 19, 21 and 22, the respective sections in Chapters 16A, 17A, 18A, 19A, 21A and 22A shall apply instead.

  Authority— Health and Safety Code Sections 127010, 127015 and 129790.

  References— Health and Safety Code Sections 127010, 127015, 1275 and 129675 through 130070.

  1.10.5 OSHPD 5. Specific scope of application of the agency responsible for enforcement, enforcement agency and the specific authority to adopt and enforce such provisions of this code, unless otherwise stated.

  Application— Acute psychiatric hospital buildings.

  Enforcing agency— Health Care Access and Information/Office of Statewide Hospital Planning and Development (OSHPD). The office shall also enforce the California Energy Commission—Energy Regulations, the Division of the State Architect—Access Compliance regulations and the regulations of the Office of the State Fire Marshal for the above-stated facility type.

  1.10.5.1 Applicable administrative standards. 1. Title 24, Part 1, California Code of Regulations: Chapter 7. 2. Title 24, Part 2, California Code of Regulations: Sections 1.1 and 1.10, Chapter 1, Division I, and as adopted in Chapter I, Division II.

  1.10.5.2 Applicable building standards. California Building Standards Code, Title 24, Parts 2, 3, 4, 5, 6, 9, 10 and 11.

  The provision of Title 24, Part 2, as adopted and amended by OSHPD, shall apply to the applications listed in Section 1.10.5.

  OSHPD 5 adopts the following building standards in Title 24, Part 2:

  Chapters 2 through 10, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 30, 31, 32, 33 and 35.

  1.10.5.3 Identification of amendments. For applications listed in Section 1.10.5, amendments appear in this code preceded with the acronym [OSHPD 5].

  Authority— Health and Safety Code Sections 127010, 127015, 1275 and 129850.

  References— Health and Safety Code Sections 127010, 127015, 129680, 1275 and 129675 through 130070.

  1.10.6 OSHPD 6. Specific scope of application of the agency responsible for enforcement, enforcement agency and the specific authority to adopt and enforce such provisions of this code, unless otherwise stated.

  Application —Chemical dependency recovery hospital not within an acute care hospital building or an acute psychiatric facility.

  Enforcing agency —Local building department.

• CBC § 1604.8.3 High relevance — show source text

  See Sections 1609 for wind design requirements and 1613 for earthquake design requirements. 1604.8.3 Decks. Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:

  1. The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on all portions of the deck.
  2. The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604.9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

  Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

  1604.10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

  SECTION 1605—LOAD COMBINATIONS

  1605.1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605.2.

  Exceptions:

  1. The modifications to load combinations of ASCE 7, Section 2.3, ASCE 7, Section 2.4 and Section 1605.2 specified in ASCE 7 Chapters 18 and 19 shall apply.

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  2. Where the allowable stress design load combinations of ASCE 7, Section 2.4 are used, flat roof snow loads of 45 pounds per square foot (2.15 kN/m [2] ) and roof live loads of 30 pounds per square foot (1.44 kN/m [2] ) or less need not be combined with seismic load. Where flat roof snow loads exceed 45 pounds per square foot (2.15 kN/m [2] ), 15 percent shall be combined with seismic loads.

  3. Where the allowable stress design load combinations of ASCE 7 Section 2.4 are used, crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind loads.

  4. Where design for tornado loads is required, the alternative allowable stress design load combinations of Section 1605.2 shall not apply when tornado loads govern the design.

• CBC § 1604.6 High relevance — show source text

  1604.6 In-situ load tests. The building official is authorized to require an engineering analysis or a load test, or both, of any construction whenever there is reason to question the safety of the construction for the intended occupancy. Engineering analysis and load tests shall be conducted in accordance with Section 1708.

  1604.7 Preconstruction load tests. Materials and methods of construction that are not capable of being designed by approved engineering analysis or that do not comply with the applicable referenced standards, or alternative test procedures in accordance with Section 1707, shall be load tested in accordance with Section 1709.

  1604.8 Anchorage. Buildings and other structures, and portions thereof, shall be provided with anchorage in accordance with Sections 1604.8.1 through 1604.8.3, as applicable. 1604.8.1 General. Anchorage of the roof to walls and columns, and of walls and columns to foundations, shall be provided to resist the uplift and sliding forces that result from the application of the prescribed loads. 1604.8.2 Structural walls. Walls that provide vertical load-bearing resistance or lateral shear resistance for a portion of the structure shall be anchored to the roof and to all floors and members that provide lateral support for the wall or that are supported by the wall. The connections shall be capable of resisting the horizontal forces that result from the application of the prescribed loads. The required earthquake out-of-plane loads are specified in Section 1.4.4 of ASCE 7 for walls of structures assigned to Seismic Design Category A and to Section 12.11 of ASCE 7 for walls of structures assigned to all other seismic design categories. Required anchors in masonry walls of hollow units or cavity walls shall be embedded in a reinforced grouted structural element of the wall. See Sections 1609 for wind design requirements and 1613 for earthquake design requirements. 1604.8.3 Decks. Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:

  1. The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on all portions of the deck.
  2. The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604.9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

  Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

  1604.10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

  SECTION 1605—LOAD COMBINATIONS

• CBC § 2.3.2 High relevance — show source text

  405 A .2.3.2 Extent of repair for compliant buildings. If the evaluation establishes that the building in its predamage condition complies with the provisions of Section 405.2.3.1, then the damaged elements shall be permitted to be restored to their predamage condition.

  405 A .2.3.3 Extent of repair for noncompliant buildings. If the evaluation does not establish that the lateral force-resisting system of the building in its predamage condition complies with the provisions of Section 405.2.3.1, then the lateral forceresisting system, and its foundation, shall be retrofitted to comply with the provisions of this section. The wind loads for the repair and retrofit shall be those required by the building code in effect at the time of original construction, unless the damage was caused by wind, in which case the wind loads shall be in accordance with the California Building Code . The earthquake loads shall not be less than those required by the building code in effect at the time of original construction but not less than 75 percent of those prescribed in California Building Code Section 1613A. Alternatively, where the earthquake damage has not resulted in disproportionate earthquake damage or did not result in collapse, the retrofit shall be permitted to be performed in accordance with Section 304A.3.4.4 for SPC-2 buildings, Section 304A.3.4.5 for SPC-3, SPC-4D and SPC-4 buildings and Section 304A.3.4.6 for SPC-5 buildings. For SPC-5 buildings, the seismic hazard shall be permitted to be reduced to BSE-1E and BSE-2E. Use of Section 304A.3.4.5 to rehabilitate SPC-3, SPC-4D and SPC-4 buildings will result in re-classification of the building to SPC-4D. Noncompliant SPC-4 buildings may be rehabilitated to SPC-5 in accordance with Section 304A.3.4.6 using the reduced seismic hazard. New structural members and connections required by this rehabilitation design shall comply with the detailing provisions of this code for new buildings of similar structure, purpose and location.

  405 A .2.4 Substantial structural damage to gravity load-carrying components. Gravity load-carrying components that have sustained substantial structural damage shall be retrofitted to comply with the applicable provisions for dead, live and snow loads in the California Building Code . Undamaged gravity load-carrying components, including undamaged foundation components, that receive dead, live or snow loads from retrofitted components shall also be retrofitted if required to comply with these design loads. New structural members and connections required by this rehabilitation design shall comply with the detailing provi- sions of this code for new buildings of similar structure, purpose and location.

  405 A .2.4.1 Lateral force-resisting elements. Regardless of the level of damage to vertical elements of the lateral force-resisting system, if substantial structural damage to gravity load-carrying components was caused primarily by wind or seismic effects, then the building shall be evaluated in accordance with Section 405 A .2.3.1 and, if noncompliant, retrofitted in accordance with Section 405 A .2.3.3.

  Exceptions:

• CBC § 3.4. High relevance — show source text

  _ 4. Site data report in accordance with the CBC 1980 shall establish that seismically induced differential settlement does not exceed 1 ″ in 40 ′ .

  5. Adjacent buildings shall satisfy the SPC building separation requirements in accordance with the California Administrative Code, Chapter 6 Section 3.4. 6. The addition of new structural elements or strengthening of existing structural elements for retrofit of nonconforming build- ings to SPC-4D shall comply with the following: a) The seismic demand (forces or displacements) shall be in accordance with the CBC 1980; b) Capacity, detailing and connections for new structural elements shall satisfy the requirements in the CBC 2025 for new construction; and c) The strengthening of existing structural elements shall use capacities determined in accordance with the CBC 2025 for new construction consistent with the detailing and connections used in the strengthened member. 7. All construction, quality assurance and quality control shall be in accordance with the new construction provisions of CBC 2025.

  8. Elements not part of the Seismic Force-Resisting System (SFRS), including those identified in the California Administrative Code Chapter 6, Article 10, shall be evaluated using seismic forces and the requirements of the CBC 1980. 9. Any column or wall that forms part of two or more intersecting SFRS and is subjected to axial load due to seismic forces acting along either principal plan axis equaling or exceeding 20 percent of the axial design strength of the column or wall shall be evaluated for the most critical load effect due to application of seismic force in any direction. The most critical load effect may be deemed to be satisfied if members and their foundations are evaluated for 100 percent of the forces for one direction plus 30 percent of the forces for the perpendicular direction, whereby the combination produces the maximum effect. Exceptions: The following buildings (with structural irregularities or unusual configuration/system) shall not be eligible for the SPC-4D upgrade using the prescriptive provisions in this section: 1. Buildings with prohibited irregularities in accordance with California Building Code 2022 Section 1617A.1.10.

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  �

  PRESCRIPTIVE COMPLIANCE METHOD

  2. Buildings taller than 5 stories or 65' height above the base having horizontal or vertical irregularities in accordance with ASCE 7-10 Tables 12.3-1 Items #1a, 1b and 3 or 12.3-2 Items #1a, 1b, 5a and 5b.

  3. Buildings with unusual configuration or structural system, as determined by the building official.

  501A.3.2 Prescriptive compliance provisions for SPC-4D using the new building design requirements of this code. Structures satisfying the requirements of the California Building Code for new general acute care hospital buildings design shall be deemed to satisfy the SPC-4D requirements of Table 2.5.3, Chapter 6 of the California Administrative Code.

• CBC § 1705A.2.1 High relevance — show source text

  Additionally, the applicable portions in Table 1705A.2.1 of the California Building Code shall apply.

  1705 A .13.1.2 Structural steel elements. Special inspections of structural steel elements in the seismic force-resisting systems of buildings and structures assigned to Seismic Design Category D, E or F other than those covered in Section 1705 A .13.1.1, including struts, collectors, chords and foundation elements, shall be performed in accordance with the quality assurance requirements of AISC 341 and this code .

  [DSA-SS, DSA-SS/CC] Quality assurance application is not permitted for the following AISC 341, Chapter J Sections: 1. J6 (Inspection Tasks). 2. J7 (Welding Inspection and Nondestructive Testing). 3. J10 (Inspection of Composite Structures). 4. J11 (Inspection of H-Piles).

  Additionally, the applicable portions in Table 1705A.2.1 of the California Building Code shall apply.

  1705 A .13.2 Structural wood. For the seismic force-resisting systems of structures assigned to Seismic Design Category D, E or F:

  1. Continuous special inspection shall be required during field gluing operations of elements of the seismic force-resisting system.
  2. Periodic special inspection shall be required for nailing, bolting, anchoring and other fastening of elements of the seismic force-resisting system, including wood shear walls, wood diaphragms, drag struts, braces, shear panels and hold-downs.

  1705 A .13.3 Cold-formed steel light-frame construction. For the seismic force-resisting systems of structures assigned to Seismic Design Category D, E or F, periodic special inspection shall be required for both:

  1. Welding operations of elements of the seismic force-resisting system.
  2. Screw attachment, bolting, anchoring and other fastening of elements of the seismic force-resisting system, including shear walls, braces, diaphragms, collectors (drag struts) and hold-downs.

  [DSA-SS, DSA-SS/CC] Requirements specified in Section 1705A.2.9 shall also apply.

  1705 A .13.4 Special inspection for special seismic certification . For structures assigned to Seismic Design Category D, E or F, the special inspector shall examine equipment and components requiring special seismic certification in accordance with Section 1705A.14.3 or ASCE 7 , Section 13.2.3 and verify that the label, anchorage and mounting conform to the certificate of compliance.

  1705 A .13.5 Architectural components. Periodic special inspection is required for the erection and fastening of exterior cladding, interior and exterior nonbearing walls, ceilings and interior and exterior veneer in structures assigned to Seismic Design Category D, E or F.

  [OSHPD 1] E x ception: Periodic special inspection is not required where continuous inspection of the work is performed in accor- dance with Section 7-145 of the CAC .

  1705 A .13.5.1 Access floors. Periodic special inspection is required for the anchorage of access floors in structures assigned to Seismic Design Category D, E or F.

• CBC § 319.8. Medium relevance — show source text

  unless it can be demonstrated that_ reduced capacity meets the requirements of Section 319.8. 2. The lateral loading to or strength requirement of existing structural components is not increased beyond their capacity. 3. New structural components are detailed and connected to the existing structural components as required by the California Building Code. 4. New or relocated nonstructural components are detailed and connected to existing or new structural components as required by the California Building Code. 5. A dangerous condition is not created.

  Use of ASCE 41 Tier 1 and Tier 2 deficiency only retrofit procedures are pre-approved for use where Section 317.3 does not require an

  assessment.

  319.12.1 State-owned buildings. [BSC] Voluntary modifications to lateral force-resisting systems conducted in accordance with Appendix A of this code and the referenced standards of the California Building Code shall be permitted.

  319.12.1.1 Design documents. [BSC] When Section 319.12 is the basis for structural modifications, the approved design documents must clearly state the scope of the seismic modifications and the accepted criteria for the design. The approved design documents must clearly have the phrase “The seismic requirements of the California Existing Building Code have not been checked to determine if these structural modifications meet the full seismic evaluation and strengthening requirements of Sections 317-322: the modifications proposed are to a different seismic performance standard than would be required in Section 319 if they were not voluntary as allowed in Section 319.12.”

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  PROVISIONS FOR ALL COMPLIANCE METHODS

  319.12.2 Public schools and community colleges. [DSA-SS, DSA-SS/CC] When Section 319.12 is the basis for structural modifications, the approved design documents must clearly indicate the scope of modifications and the acceptance criteria for the design.

  SECTION 320 [BSC, DSA-SS & DSA-SS/CC]—METHOD A

  320.1 General. The retrofit design shall employ the Linear Static or Linear Dynamic Procedures of ASCE 41, Section 7.4.1 or 7.4.2, and comply with the applicable general requirements of ASCE 41, Chapters 6 and 7. The earthquake hazard level and performance level given specified in Section 317.5 for the building’s risk category shall be used. Structures shall be designed for seismic forces coming from any horizontal direction.

  SECTION 321 [BSC, DSA-SS & DSA-SS/CC]—METHOD B

  321.1 The existing or retrofitted structure shall be demonstrated to have the capability to sustain the deformation response due to the specified earthquake ground motions and meet the seismic performance requirements of Section 317. The registered design professional shall provide an evaluation of the response of the existing structure in its modified configuration and condition to the ground motions specified. If the building’s seismic performance is evaluated as satisfactory and the peer reviewer(s) and the enforcement agency concurs, then no further structural retrofit and/or repair of the lateral load-resisting system is required.

• CBC § 1617A.1.14 Medium relevance — show source text

  1617A.1.14 Reserved.

  1617A.1.15 ASCE 7, Section 12.13.1. Modify ASCE 7, Section 12.13.1 by adding Section 12.13.1.1 as follows:

  12.13.1.1 Foundations and superstructure-to-foundation connections. The foundation shall be capable of transmitting the design base shear and the overturning forces from the structure into the supporting soil. Stability against overturning and sliding shall be in accordance with Section 1605A.1.1.

  In addition, the foundation and the connection of the superstructure elements to the foundation shall have the strength to resist, in addition to gravity loads, the lesser of the following seismic loads: 1. The strength of the superstructure elements. 2. The maximum forces that can be delivered to the foundation in a fully yielded structural system. 3. Forces from the load combinations with overstrength factor in accordance with ASCE 7, Section 12.4.3.1.

  Exceptions: 1. Where referenced standards specify the use of higher design loads. 2. When it can be demonstrated that inelastic deformation of the foundation and superstructure-to-foundation connec- tion will not result in a weak story or cause collapse of the structure. 3. Where seismic force-resisting system consists of light framed walls with shear panels, unless the reference standard specifies the use of higher design loads.

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  Where the computation of the seismic overturning moment is by the equivalent lateral-force method or the modal analysis method, reduction in overturning moment permitted by section 12.13.4 of ASCE 7 may be used.

  Where moment resistance is assumed at the base of the superstructure elements, the rotation and flexural deformation of the foundation as well as deformation of the superstructure-to-foundation connection shall be considered in the drift and deforma- tion compatibility analyses.

  1617A.1.16 ASCE 7, Section 12.13.9.2. Modify ASCE 7, Section 12.13.9.2 by adding the following sentence at the end of the exception:

  Seismic load effects determined in accordance with Section 12.4 need not be considered in this check.

  1617A.1.17 ASCE 7, Section 13.1.3. [OSHPD 1 & 4] Modify ASCE 7, Section 13.1.3 by the following: All nonstructural components shall have a component importance factor, I p , equal to 1.5. Exception: Hospital buildings rated SPC-1 and SPC-2 not providing services/systems, utilities or access/egress to general acute care buildings designated as SPC 3 or higher in accordance with Chapter 6 of the California Administrative Code, shall be permit- ted to use component importance factor, I p , as given in ASCE 7, Section 13.1.3. 1617A.1.18 ASCE 7, Section 13.1.4. Replace ASCE 7, Section 13.1.4, with the following:

  13.1.4 _**.

• CBC § 2.1 High relevance — show source text

  DCR = 2.1 S D1 W d /Σ v u D + V cb

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  APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

  3. For diaphragms in a multiple-story building with qualifying crosswalls in all levels:

  Equation A1-9 DCR = 2.1 S D1 ΣW d / ΣΣ( v u D + V cb )

  DCR shall be calculated at each level for the set of diaphragms at and above the level under consideration. In addition, the roof diaphragm shall meet the requirements of Equation A1-10. 4. For a roof diaphragm and the diaphragm directly below, if coupled by crosswalls:

  Equation A1-10 DCR = 2.1 S D1 Σ W d /ΣΣ v u D

  [BS] A111.4.3 Chords. An analysis for diaphragm flexure need not be made, and chords need not be provided.

  [BS] A111.4.4 Collectors. An analysis of diaphragm collector forces shall be made for the transfer of diaphragm edge shears into vertical elements of the lateral force-resisting system. Collector forces may be resisted by new or existing elements.

  [BS] A111.4.5 Diaphragm openings.

  1. Diaphragm forces at corners of openings shall be investigated and shall be developed into the diaphragm by new or existing materials.
  2. In addition to the demand-capacity ratios of Section A111.4.2, the demand-capacity ratio of the portion of the diaphragm adjacent to an opening shall be calculated using the opening dimension as the span.
  3. Where an opening occurs in the end quarter of the diaphragm span, the calculation of v u D for the demand-capacity ratio shall be based on the net depth of the diaphragm.

  [BS] A111.5 Diaphragm shear transfer. Diaphragms shall be connected to shear walls and new vertical seismic force-resisting elements with connections capable of developing the diaphragm-loading tributary to the shear wall or new seismic force-resisting elements given by the lesser of the following formulas: Equation A1-11 V = 1.2 S D1 C p W d using the C p values in Table A111.5, or Equation A1-12 V = v u D

  DCR = 2.1 S D1 ΣW d / ΣΣ( v u D + V cb )

  DCR = 2.1 S D1 Σ W d /ΣΣ v u D

  V = 1.2 S D1 C p W d

  V = v u D

• CBC § A203 Medium relevance — show source text

  [BS] A202.1 Scope. The provisions of this chapter shall apply to wall anchorage systems that resist out-of-plane forces and to collectors in existing reinforced concrete or reinforced masonry buildings with flexible diaphragms. Wall anchorage systems that were designed and constructed in accordance with the 1997 Uniform Building Code or the 2001 or subsequent editions of the California Building Code shall be deemed to comply with these provisions.

  SECTION A203—DEFINITIONS

  [BS] A203.1 Definitions. For the purpose of this chapter, the applicable definitions in the California Building Code and the following shall apply:

  [BS] CONTINUITY CONNECTOR. A component, typically a plate, rod, strap or hold-down, that ensures load path continuity along the full length of a crosstie or strut.

  [BS] CROSSTIE. A member or group of members continuous across the main diaphragm that connects opposite wall lines and transfers out-of-plane wall anchorage forces into the diaphragm.

  [BS] FLEXIBLE DIAPHRAGM. A roof or floor sheathed with plywood, wood decking (1-by or 2-by) or metal deck without a concrete topping slab.

  [BS] STRUT. A member or group of members continuous across a subdiaphragm that transfers out-of-plane wall anchorage forces into the subdiaphragm.

  [BS] WALL ANCHORAGE SYSTEM. The components comprising a complete load path for out-of-plane wall forces from the wall to the main diaphragm, typically including anchors embedded in or fastened to the wall; rods, straps, plates, hold-downs or other hardware; subdiaphragms and their chords; crossties; struts; and continuity connectors.

  [BS] WALL SEGMENT. Any length of concrete wall with continuous horizontal reinforcing and not interrupted or intersected by a pilaster or vertical construction joint, or any length of reinforced masonry wall with continuous horizontal reinforcing and not interrupted or intersected by a pilaster or vertical control joint.

  SECTION A204—SYMBOLS AND NOTATIONS

  [BS] A204.1 General. For the purpose of this chapter, the applicable symbols and notations in the California Building Code shall apply.

  SECTION A205—GENERAL REQUIREMENTS

  [BS] A205.1 General. The seismic-resisting elements specified in this chapter shall comply with applicable provisions of Section 1613 of the California Building Code and Chapter 12 of ASCE 7, except as modified herein.

  [BS] A205.2 Requirements for plans. The plans shall accurately reflect the results of the engineering investigation and design and shall show all pertinent dimensions and sizes for plan review and construction. The following shall be provided:

  1. Floor plans and roof plans shall show existing framing construction, diaphragm construction, proposed wall anchors, crossties and collectors. Existing nailing, anchors, crossties and collectors shall be shown on the plans if they are considered part of the lateral force-resisting systems.
  2. Typical wall panel details and sections with panel thickness, height, pilasters and location of anchors shall be provided.
  3. Details shall include existing and new anchors and the method of developing anchor forces into the diaphragm framing, existing and new crossties, and existing and new or improved support of roof and floor girders at pilasters or walls.
  4. The basis for design and the building code used for the design shall be stated on the plans.
• CBC § 1704.6 Medium relevance — show source text

  [BS] WALL SEGMENT. Any length of concrete wall with continuous horizontal reinforcing and not interrupted or intersected by a pilaster or vertical construction joint, or any length of reinforced masonry wall with continuous horizontal reinforcing and not interrupted or intersected by a pilaster or vertical control joint.

  SECTION A204—SYMBOLS AND NOTATIONS

  [BS] A204.1 General. For the purpose of this chapter, the applicable symbols and notations in the California Building Code shall apply.

  SECTION A205—GENERAL REQUIREMENTS

  [BS] A205.1 General. The seismic-resisting elements specified in this chapter shall comply with applicable provisions of Section 1613 of the California Building Code and Chapter 12 of ASCE 7, except as modified herein.

  [BS] A205.2 Requirements for plans. The plans shall accurately reflect the results of the engineering investigation and design and shall show all pertinent dimensions and sizes for plan review and construction. The following shall be provided:

  1. Floor plans and roof plans shall show existing framing construction, diaphragm construction, proposed wall anchors, crossties and collectors. Existing nailing, anchors, crossties and collectors shall be shown on the plans if they are considered part of the lateral force-resisting systems.
  2. Typical wall panel details and sections with panel thickness, height, pilasters and location of anchors shall be provided.
  3. Details shall include existing and new anchors and the method of developing anchor forces into the diaphragm framing, existing and new crossties, and existing and new or improved support of roof and floor girders at pilasters or walls.
  4. The basis for design and the building code used for the design shall be stated on the plans.

  [BS] A205.3 Structural observation. Structural observation, in accordance with Section 1704.6 of the California Building Code is required, regardless of seismic design category, height or other conditions. Structural observation shall include visual observation of work for conformance to the approved construction documents and confirmation of existing conditions assumed during design.

  A205.3.1 Additional special inspection. In addition to the requirements of Section 1705.13 of the California Building Code, special inspection shall be required for:

  1. Installation of anchors into existing concrete or masonry walls to form part of a wall anchorage system.

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  APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

  2. Fastening of new or existing steel deck forming part of a wall anchorage system.
  3. Installation of continuity connectors along the length of crossties, to ensure compliance with Section A206.2. This inspection may be periodic special inspection.

  A205.3.2 Testing to establish adequacy of existing wall anchors. Testing shall show that the existing anchors can sustain a test load of 1.5 times the design tension load without noticeable deformation or damage to the anchor, to the masonry or concrete element, or to any part of the existing load path between the anchor and new retrofit components. Three anchors of each existing detail type shall be tested, and all three shall satisfy the requirement. Prior to testing, the design professional shall submit a test plan for code official approval identifying the expected locations of the existing anchors in question, the locations of the proposed tests, and the test procedure and criteria.

• CBC § 304.8 Medium relevance — show source text

  0 2

  3 3 4 5 6

  DEMAND-CAPACITY RATIO, DCR

  1. Region of demand-capacity ratios where crosswalls may be used to increase h/t ratios.
  2. Region of demand-capacity ratios where h/t ratios of “buildings with crosswalls” may be used, whether or not crosswalls are present.
  3. Region of demand-capacity ratios where h/t ratios of “all other buildings” shall be used, whether or not crosswalls are present.

  For SI: 1 foot = 304.8 mm.

  [BS] A111.4.2 Demand-capacity ratios. Demand-capacity ratios shall be calculated for the diaphragm at any level according to the following formulas:

  1. For a diaphragm without qualifying crosswalls at levels immediately above or below:

  Equation A1-7 DCR = 2.1 S D1 W d /Σ v u D 2. For a diaphragm in a single-story building with qualifying crosswalls, or for a roof diaphragm coupled by crosswalls to the diaphragm directly below:

  Equation A1-8 DCR = 2.1 S D1 W d /Σ v u D + V cb

  DCR = 2.1 S D1 W d /Σ v u D

  DCR = 2.1 S D1 W d /Σ v u D + V cb

  APPENDIX A-12 2025 CALIFORNIA EXISTING BUILDING CODE

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  APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

  3. For diaphragms in a multiple-story building with qualifying crosswalls in all levels:

  Equation A1-9 DCR = 2.1 S D1 ΣW d / ΣΣ( v u D + V cb )

  DCR shall be calculated at each level for the set of diaphragms at and above the level under consideration. In addition, the roof diaphragm shall meet the requirements of Equation A1-10. 4. For a roof diaphragm and the diaphragm directly below, if coupled by crosswalls:

  Equation A1-10 DCR = 2.1 S D1 Σ W d /ΣΣ v u D

  [BS] A111.4.3 Chords. An analysis for diaphragm flexure need not be made, and chords need not be provided.

  [BS] A111.4.4 Collectors. An analysis of diaphragm collector forces shall be made for the transfer of diaphragm edge shears into vertical elements of the lateral force-resisting system. Collector forces may be resisted by new or existing elements.

• CBC § 1.11. Medium relevance — show source text

  The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

  2025 CALIFORNIA EXISTING BUILDING CODE APPENDIX A-19

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  APPENDIX A-20 2025 CALIFORNIA EXISTING BUILDING CODE

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

  CHAPTER A2

  EARTHQUAKE HAZARD REDUCTION IN EXISTING REINFORCED CONCRETE AND REINFORCED MASONRY WALL BUILDINGS WITH FLEXIBLE DIAPHRAGMS

  SECTION A201—PURPOSE

  [BS] A201.1 Purpose. The purpose of this chapter is to promote public safety and welfare by reducing the risk of death or injury as a result of the effects of earthquakes on reinforced concrete and reinforced masonry wall buildings with flexible diaphragms. Based on past earthquakes, these buildings have been categorized as being potentially hazardous and prone to significant damage, including possible collapse in a moderate to major earthquake. The provisions of this chapter are minimum standards for structural seismic resistance established primarily to reduce the risk of life loss or injury on both subject and adjacent properties. These provisions will not necessarily prevent loss of life or injury, or prevent earthquake damage to an existing building that complies with these standards.

  SECTION A202—SCOPE

  [BS] A202.1 Scope. The provisions of this chapter shall apply to wall anchorage systems that resist out-of-plane forces and to collectors in existing reinforced concrete or reinforced masonry buildings with flexible diaphragms. Wall anchorage systems that were designed and constructed in accordance with the 1997 Uniform Building Code or the 2001 or subsequent editions of the California Building Code shall be deemed to comply with these provisions.

  SECTION A203—DEFINITIONS

  [BS] A203.1 Definitions. For the purpose of this chapter, the applicable definitions in the California Building Code and the following shall apply:

  [BS] CONTINUITY CONNECTOR. A component, typically a plate, rod, strap or hold-down, that ensures load path continuity along the full length of a crosstie or strut.

  [BS] CROSSTIE. A member or group of members continuous across the main diaphragm that connects opposite wall lines and transfers out-of-plane wall anchorage forces into the diaphragm.

  [BS] FLEXIBLE DIAPHRAGM. A roof or floor sheathed with plywood, wood decking (1-by or 2-by) or metal deck without a concrete topping slab.

  [BS] STRUT. A member or group of members continuous across a subdiaphragm that transfers out-of-plane wall anchorage forces into the subdiaphragm.

  [BS] WALL ANCHORAGE SYSTEM. The components comprising a complete load path for out-of-plane wall forces from the wall to the main diaphragm, typically including anchors embedded in or fastened to the wall; rods, straps, plates, hold-downs or other hardware; subdiaphragms and their chords; crossties; struts; and continuity connectors.

• CBC § 2.5.4. Medium relevance — show source text

  agency. 2. Rooftop or other supported structures not exceeding two stories in height and 10 percent of the total struc- ture weight can use the systems in this section when designed as components per ASCE 7, Chapter 13. 3. Systems listed in this section can be used for seismically isolated buildings when permitted by ASCE 7, Section 17.2.5.4.

  1617.12.3 ASCE 7, Section 12.2.5.6.1. The exception in Item a is not permitted by DSA-SS/CC.

  1617.12.4 ASCE 7, Section 12.2.5.7.1. The exception in Item a is not permitted by DSA-SS/CC.

  1617.12.5 ASCE 7, Section 12.2.5.7.2. The exception in Item a is not permitted by DSA-SS/CC.

  1617.12.6 ASCE 7, Section 12.3.3.1. Replace ASCE 7, Section 12.3.3.1 by the following:

  12.3.3.1 Prohibited vertical irregularities for Seismic Design Categories D through F. Structures assigned to Seismic Design Category E or F that have vertical irregularities Type 1b, 4a or 4b of Table 12.3-2 shall not be permitted. Structures assigned to Seismic Design Category D having vertical irregularity Type 1b or 4b of Table 12.3-2 shall not be permitted.

  Exception: Structures assigned to Seismic Design Category E or F that have vertical irregularity Type 4a shall be permitted where the story lateral strength is not less than 80 percent of that in the story above.

  1617.12.7 ASCE 7, Section 12.7.2. Modify ASCE 7, Section 12.7.2 by adding Item 7 to read as follows: 7. Where buildings provide lateral support for walls retaining earth, and the exterior grades on opposite sides of the building differ by more than 6 feet (1829 mm), the load combination of the seismic increment of earth pressure due to earthquake acting on the higher side, as determined by a Geotechnical engineer qualified in soils engineering, plus the difference in earth pressures shall be added to the lateral forces provided in this section.

  1617.12.8 ASCE 7, Section 12.10.2.1. Replace Exception to ASCE 7, Section 12.10.2.1 by the following:

  Exception: In light-frame structures or portions thereof braced entirely by wood light-frame shear walls, collector elements and their connections, including connections to vertical elements, need only be designed to resist forces using the load combinations of Section 2.3.6 with seismic forces determined in accordance with Section 12.10.1.1.

  1617.12.9 ASCE 7, Section 12.13.1. Modify ASCE 7, Section 12.13.1 by adding Section 12.13.1.1 as follows:

• CBC § 1705.14.1.2 Medium relevance — show source text

  1705.14.1.2 Structural steel elements. Nondestructive testing of structural steel elements in the seismic force-resisting systems of buildings and structures assigned to Seismic Design Category B, C, D, E or F other than those covered in Section 1705.14.1.1, including struts, collectors, chords and foundation elements, shall be performed in accordance with the quality assurance requirements of AISC 341. [OSHPD 1R, 2 & 5] and this code.

  Exceptions: [OSHPD 1R, 2 & 5] Not permitted by OSHPD.

  1. In buildings and structures assigned to Seismic Design Category B or C, nondestructive testing of structural steel elements is not required for seismic force-resisting systems with a response modification coefficient, R, of 3 or less.
  2. In structures assigned to Seismic Design Category D, E or F, nondestructive testing of structural steel elements is not required for seismic force-resisting systems where design and detailing other than AISC 341 is permitted by ASCE 7, Table 15.4-1. Nondestructive testing of structural steel elements shall be in accordance with the applicable referenced standard listed in ASCE 7, Table 15.4-1.

  17-16 2025 CALIFORNIA BUILDING CODE

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  SPECIAL INSPECTIONS AND TESTS

  1705.14.2 Nonstructural components. For structures assigned to Seismic Design Category B, C, D, E or F, where the requirements of Section 13.2.1 of ASCE 7 for nonstructural components, supports or attachments are met by seismic qualification as specified in Item 2 therein, the registered design professional shall specify on the approved construction documents the requirements for seismic qualification by analysis, testing or experience data. Certificates of compliance for the seismic qualification shall be submitted to the building official as specified in Section 1704.5.

  [OSHPD 1R, 2 & 5] Seismic sway bracing components satisfying requirements of ANSI/FM 1950, ANSI/ASHRAE 171, or using an alter- native testing protocol approved by the building official shall be deemed to satisfy the requirements of this section.

  Note: Deemed to comply provisions provide acceptable options to comply with the code but do not mandate their use. Alternative systems in accordance with Section 104.2.3 and the California Administrative Code Section 7-104 are always acceptable when approved by the building official.

  1705.14.3 Designated seismic systems. For structures assigned to Seismic Design Category C, D, E or F and with designated seismic systems that are subject to the requirements of Section 13.2.4 of ASCE 7 for certification, the registered design professional shall specify on the approved construction documents the requirements to be met by analysis, testing or experience data as specified therein. Certificates of compliance documenting that the requirements are met shall be submitted to the building official as specified in Section 1704.5.

• CBC § 12.11.2.2 Medium relevance — show source text

  Where new members are added as crossties, they shall be spaced no more than 24 feet (7315 mm) apart. Where existing girders are used as crossties, their actual spacing shall be deemed adequate even where the spacing exceeds 24 feet (7315 mm), as long as the girders are provided with continuity connectors as required.

  Wall anchorage shall not be provided by fastening the edge of plywood sheathing to steel ledgers. Wall anchorage shall not be provided solely by fastening the edge of steel decking to steel ledgers unless analysis demonstrates acceptable capacity. The existing connections shall be subject to field verification and the new connections shall be subject to special inspection.

  New wall anchors shall be provided to resist the full wall anchorage design force independent of existing shear or tension anchors.

  Exception: Existing cast-in-place anchors shall be permitted as part of the wall anchorage system if the tie element can be readily attached to the anchors, and if the anchors are capable of resisting the total vertical and lateral shear load (including dead load) while being acted on by the maximum wall anchorage tension force caused by an earthquake. Acceptable tension values for the existing anchors shall be established by testing in accordance with Section A205.4.

  [BS] A206.3 Development of anchor forces into the diaphragm. Development of the required anchorage forces into roof and floor diaphragms shall comply with the requirements of this section and Section 12.11.2.2 of ASCE 7.

  Lengths of development of anchor loads in wood diaphragms shall be based on existing field nailing of the sheathing unless existing edge nailing is positively identified on the original construction plans or at the site.

  [BS] A206.4 Anchorage at pilasters. Where pilasters are present, the wall anchorage system shall comply with the requirements of this section and Section 12.11.2.2.7 of ASCE 7. The pilasters or the walls immediately adjacent to the pilasters shall be anchored directly to the roof framing such that the existing vertical anchor bolts at the top of the pilasters are bypassed without permitting tension or shear failure at the top of the pilasters.

  Exception: If existing vertical anchor bolts at the top of the pilasters are used for the anchorage, additional exterior confinement shall be provided as required to resist the total anchorage force.

  [BS] A206.5 Combination of anchor types. New anchors used in combination on a single framing member shall be of compatible behavior and stiffness.

  [BS] A206.6 Anchorage at interior walls. Existing interior reinforced concrete or reinforced masonry walls that extend to the floor above or to the roof diaphragm shall be anchored for out-of-plane forces per Sections A206.1 and A206.3. Walls extending through

  APPENDIX A-22 2025 CALIFORNIA EXISTING BUILDING CODE

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  APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

  the roof diaphragm shall be anchored for out-of-plane forces on both sides, and continuity ties shall be spliced across or continuous through the interior wall to provide diaphragm continuity.

  [BS] A206.7 Collectors. Collectors designed in accordance with this section shall be provided at reentrant corners and at interior shear walls.

• CBC § 12.3 Medium relevance — show source text

  1705 A .12.3 Wind-resisting components. Periodic special inspection is required for fastening of the following systems and components:

  1. Roof covering, roof deck and roof framing connections.
  2. Exterior wall covering and wall connections to roof and floor diaphragms and framing.

  1705 A .13 Special inspections for seismic resistance. Special inspections for seismic resistance shall be required as specified in Sections 1705 A .13.1 through 1705 A .13.9, unless exempted by the exceptions of Section 1704 A .2.

  1705 A .13.1 Structural steel. Special inspections for seismic resistance shall be in accordance with Section 1705 A .13.1.1 or 1705 A .13.1.2, as applicable.

  1705 A .13.1.1 Seismic force-resisting systems. Special inspections of structural steel in the seismic force-resisting systems in buildings and structures assigned to Seismic Design Category D, E or F shall be performed in accordance with the quality assurance requirements of AISC 341 and this code.

  [DSA-SS, DSA-SS/CC] Quality assurance application is not permitted for the following AISC 341, Chapter J Sections: 1. J6 (Inspection Tasks).

  17A-16 2025 CALIFORNIA BUILDING CODE

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  SPECIAL INSPECTIONS AND TESTS

  2. J7 (Welding Inspection and Nondestructive Testing). 3. J10 (Inspection of Composite Structures). 4. J11 (Inspection of H-Piles).

  Additionally, the applicable portions in Table 1705A.2.1 of the California Building Code shall apply.

  1705 A .13.1.2 Structural steel elements. Special inspections of structural steel elements in the seismic force-resisting systems of buildings and structures assigned to Seismic Design Category D, E or F other than those covered in Section 1705 A .13.1.1, including struts, collectors, chords and foundation elements, shall be performed in accordance with the quality assurance requirements of AISC 341 and this code .

  [DSA-SS, DSA-SS/CC] Quality assurance application is not permitted for the following AISC 341, Chapter J Sections: 1. J6 (Inspection Tasks). 2. J7 (Welding Inspection and Nondestructive Testing). 3. J10 (Inspection of Composite Structures). 4. J11 (Inspection of H-Piles).

  Additionally, the applicable portions in Table 1705A.2.1 of the California Building Code shall apply.

  1705 A .13.2 Structural wood. For the seismic force-resisting systems of structures assigned to Seismic Design Category D, E or F:

  1. Continuous special inspection shall be required during field gluing operations of elements of the seismic force-resisting system.
  2. Periodic special inspection shall be required for nailing, bolting, anchoring and other fastening of elements of the seismic force-resisting system, including wood shear walls, wood diaphragms, drag struts, braces, shear panels and hold-downs.