CEBC · California Existing Building Code
How do voluntary seismic modifications interact with CEBC evaluation/retrofit rules?
If you voluntarily strengthen a building in California under CEBC §319.12, you may use an approved alternate seismic performance approach, but you cannot reduce existing component capacity (unless justified per §319.8), you cannot increase demands beyond component capacity, you must detail and connect new elements per the CBC, avoid creating dangerous conditions, and (for state and school buildings) include the required scope/acceptance‑criteria statements in the approved design documents.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
Voluntary work to improve a building’s lateral‑force resisting system is permitted to follow an alternate, approved seismic performance criteria instead of a full retrofit — provided the work meets the limitations and documentation requirements in § 319.12. For state‑owned buildings the code authorizes voluntary modifications following Appendix A and requires a clear statement in the design documents that the CEBC retrofit/evaluation requirements were not checked for the voluntary scope (see § 319.12.1 and § 319.12.1.1). For public schools and community colleges, similar documentary clarity is required (see § 319.12.2) .
The single most important rule: voluntary seismic upgrades may follow a different, approved performance standard — but they cannot worsen existing components, cannot increase demands beyond a component’s capacity, must not create a dangerous condition, and must be documented as voluntary in the design documents (see § 319.12) .
Requirements in detail
Scope and purpose
- Voluntary modifications = work initiated to improve lateral strength or stiffness that is not required by other CEBC provisions. Such work is allowed to use an approved seismic performance criteria other than the one that would apply if the work were required under Sections 317–322 (see § 319.12) .
Four key limitations that must be met
The engineering analysis for voluntary work must show all of the following (text summarized from § 319.12):
- The capacity of existing components is not reduced, unless reduction is demonstrated to meet Section 319.8.
- The lateral loading to or strength requirement of existing components is not increased beyond their capacity.
- New structural components must be detailed and connected to existing components as required by the CBC.
- New or relocated nonstructural components must be detailed and connected as required by the CBC.
- The modification must not create a dangerous condition.
Additionally, ASCE 41 Tier 1 and Tier 2 deficiency‑only procedures are pre‑approved where Section 317.3 does not require a full assessment .
Table — decision‑relevant dimensions
| Decision dimension | Allowed / Required value | Code reference |
|---|---|---|
| Can existing component capacity be reduced? | Only if demonstrated to meet § 319.8 | § 319.12 |
| Can lateral demand on existing components be increased? | No — not beyond their capacity | § 319.12 |
| Documentation for state‑owned buildings | Design docs must state scope, acceptance criteria and explicitly that CEBC seismic evaluation/strengthening requirements were not checked for this voluntary standard | § 319.12.1 & § 319.12.1.1 |
| Documentation for public schools/community colleges | Approved design docs must indicate scope and acceptance criteria | § 319.12.2 |
| Use of ASCE 41 Tier 1/2 procedures | Pre‑approved where Section 317.3 does not require an assessment | § 319.12 |
| Detailing & connections for new elements | Must follow CBC detailing and connection requirements | § 319.12 |
| Creation of dangerous conditions | Prohibited | § 319.12 |
Design document and approval requirements (high level)
- For state‑owned buildings: when the voluntary route of § 319.12 is used, the approved design documents must clearly state the seismic scope and acceptance criteria and include the specific statement required by § 319.12.1.1 (that CEBC seismic requirements were not checked for the voluntary scope) .
- For public schools and community colleges: the approved design documents must clearly indicate scope and acceptance criteria when using § 319.12 .
Exceptions & special cases
- Pre‑approved use of ASCE 41 Tier 1 and Tier 2 deficiency‑only procedures is allowed where Section 317.3 does not require an assessment; that means limited, lower‑risk voluntary work can often use faster ASCE 41 prescribed procedures (see § 319.12) .
- If a component’s capacity is reduced and the exception in § 319.12 is relied on, that component cannot be treated as part of the primary lateral‑load‑resisting system (per the related exception language in the CEBC) — the code treats such reductions carefully (see the exception notes tied to component reduction and to Section 319.8) .
- Voluntary modifications that trigger thresholds in Section 317.3 (for example cumulative construction cost or changes increasing seismic demands above certain percentages) may instead require full evaluation or retrofit under Section 317 — i.e., voluntary work is not a route to avoid mandatory evaluation/retrofit when the project meets the triggers in § 317.3 .
Common mistakes
- Assuming voluntary work can ignore CEBC seismic detailing and connection rules — new elements still must be detailed and connected in accordance with the CBC (mistake: ignoring § 319.12(3)) .
- Reducing an existing member’s capacity without documenting a show‑cause demonstration per § 319.8 and the allowance in § 319.12 — permits are likely to be denied or require revision (mistake: failing to meet § 319.12’s first limitation) .
- Failing to label design documents for state‑owned projects as required by § 319.12.1.1 — omission can cause approval delays (mistake: incomplete documentation) .
- Treating ASCE 41 Tier 1/2 as universally acceptable for voluntary work even when Section 317.3 does require a full assessment — check applicability first (mistake: misapplying pre‑approval) .
Worked example — concrete scenario
Scenario: An owner of a small state‑owned, 2‑story office building decides to add a new shear‑wall line and remove one old steel strap brace in the same story.
Step 1 — inventory and baseline: the old steel strap provided an expected shear capacity of 100 kips for that line; the building’s current demand on that line under code seismic loading is 95 kips.
Step 2 — proposed voluntary change: the new shear wall adds an expected shear capacity of 40 kips, but removal of the brace would reduce the existing line capacity by 15 kips (a 15% reduction), i.e., to 85 kips.
How to proceed under the CEBC:
- The engineer must show the combined modified system meets the acceptance criteria used for the voluntary upgrade and must not increase the lateral demand on existing components beyond their capacity — here, the combined capacity after modification = 85 (remaining existing) + 40 (new wall) = 125 kips, which exceeds the prior demand of 95 kips. That satisfies the non‑increase rule in § 319.12 so long as the calculation is documented and the reduction of the original component is justified under § 319.8 if required (see § 319.12(1) and § 319.12(2)) .
- Because the building is state‑owned, the approved design documents must state the scope and acceptance criteria and include the required statement that the CEBC full evaluation/strengthening provisions were not checked for this voluntary standard (see § 319.12.1 and § 319.12.1.1) .
- If Section 317.3’s thresholds applied (e.g., cumulative cost or change in component seismic forces >10%), the voluntary route might not be available and a full evaluation under Section 317 would be required; the engineer should confirm these triggers before relying solely on § 319.12 .
Note: the numbers above are illustrative. The controlling CEBC requirement is the demonstration and documentation required by § 319.12 and the design‑document statements required by § 319.12.1 / § 319.12.1.1 where applicable .
Related provisions
- § 317.11 — Voluntary lateral‑force resisting system modifications referenced to § 319.12 (context for voluntary modifications) .
- § 319.8 — (Referenced limitation for allowed capacity reductions; demonstration requirement) .
- § 317.3 — Applicability triggers that may require a full seismic assessment despite voluntary intent (cost/force thresholds) .
- § 319.1 / § 319.1.1 — Basis for selection of seismic evaluation/design methods; Appendix A options for state buildings (ties into § 319.12.1) .
- § 319.10 — Structural observation/testing/inspection requirements that still apply to retrofit work (including voluntary modifications) .
Code references
Grounded in the retrieved California Existing Building Code — click a citation to read the verbatim passage:
CEBC § 319.8. High 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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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.
CEBC § 319.9 High relevance — show source text
Exception: A component’s strength is permitted to be less than that required by the specified seismic load combinations if it can be demonstrated that the associated reduction in seismic performance of the component or its removal due to the failure does not result in a structural system that does not comply with the required performance objectives of Section 317. If this exception is taken for a component, then it cannot be considered part of the primary lateral-load-resisting system.
319.9 Nonstructural component requirements. Where the nonstructural performance levels required by Section 317, Table 317.5 are N-D or higher, mechanical, electrical and plumbing components shall comply with the provisions of ASCE 41, Chapter 13, Section 13.2.
Exception: Modifications to the procedures and criteria may be made subject to approval by the building official, and concurrence of the peer reviewer if applicable. All reports and correspondence shall also be forwarded to the building official.
319.10 Structural observation, testing and inspection. Structural observation, testing and inspection as used in this section shall mean meeting the requirements of Chapter 17 of the California Building Code, with a minimum allowable level of investigation corresponding to seismic design category (SDC) D. Structural observation visits shall occur at significant construction stages and at the completion of the structural retrofit. Structural observation shall be provided for all structures.
Additional requirements: [DSA-SS, DSA-SS/CC] For public schools and community colleges, construction material testing, inspection and observation during construction shall also comply with the California Administrative Code.
319.10.1 The requirement for structural observation shall be noted and prominently displayed on the front sheet of the approved plans and incorporated into the general notes on the approved plans.
319.10.2 Preconstruction meeting. A preconstruction meeting is mandatory for all projects which require structural observation. The meeting shall include, but is not limited to, the registered design professional, structural observer, general constructor, affected subcontractors, the project inspector and a representative of the enforcement agency (designated alternates may attend if approved by the structural observer). The structural observer shall schedule and coordinate this meeting. The purpose of the meeting is to identify and clarify all essential structural components and connections that affect the lateral and vertical load systems and to review scheduling of the required observations for the project’s structural system retrofit.
319.11 Temporary actions. When compatible with the building use, and the time phasing for both use and the retrofit program, temporary shoring or other structural support is permitted to be considered. Temporary bracing, shoring and prevention of falling hazards are permitted to be used to qualify for Item 1 in Section 319.12 that allows inadequate capability in some existing components, as long as the required performance levels given in Section 317 can be provided by the permanent structure. The consideration for such temporary actions shall be noted in the design documents.
319.12 Voluntary modifications to the lateral-force resisting system. Where modifications of existing structural components and additions of new structural components are initiated for the purpose of improving the lateral-force resisting strength or stiffness of an existing structure and they are not required by other sections of this code, then they are permitted to be designed to meet an approved seismic performance criteria provided that an engineering analysis is submitted that follows: 1. The capacity of existing structural components required to resist forces is not reduced, unless it can be demonstrated that
CEBC § 3-20 High relevance — show source text
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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.
When the evaluation indicates the building does not meet the required performance levels given in Table 317.5 for the risk category, then a retrofit and/or repair design shall be prepared that provides a structure that meets these performance objectives and reflects the appropriate consideration of existing conditions. Any approach to analysis and design is permitted to be used, provided that the approach shall be rational, shall be consistent with the established principals of mechanics and shall use the known performance characteristics of materials and assemblages under reversing loads typical of severe earthquake ground motions.
Exception: Further consideration of the structure’s seismic performance may be waived by the enforcement agency if both the registered design professional and peer reviewer(s) conclude that the structural system can be expected to perform at least as well as required by the provisions of this section without completing an analysis of the structure’s compliance with these requirements. A detailed report shall be submitted to the responsible building official that presents the reasons and basis for this conclusion. This report shall be prepared by the registered design professional. The peer reviewer(s) shall concur in this conclusion and affirm to it in writing. The building official shall either approve this decision or require completion of the indicated work specified in this section prior to approval.
321.2 The approach, models, analysis procedures, assumptions on material and system behavior and conclusions shall be peer reviewed in accordance with the requirements of Section 322 and accepted by the peer reviewer(s).
Exceptions: 1. The enforcement agency may perform the work of peer review when qualified staff is available within the jurisdiction. 2. The enforcement agency may modify or waive the requirements for peer review when appropriate.
CEBC § 319.1 High relevance — show source text
Buildings complying with the requirements of the exception in Section 319.1 are deemed to meet the seismic performance requirements of this section._
4. State-owned and state-leased essential services buildings are subject to the regulatory authority of DSA-SS per Section 1.9.2.1.|317.6 Retrofit required. Where the evaluation indicates the building does not meet the required performance objectives of this section, the owner shall take appropriate steps to ensure that the building’s structural system is retrofitted in accordance with the provisions of Section 317. Appropriate steps are either: 1) undertake the seismic retrofit as part of the additions, alterations and/or repairs of the structure; or 2) provide a plan, acceptable to the building official, to complete the seismic retrofit in a timely manner. The relocation or moving of an existing building is considered to be an alteration requiring filing of the plans and specifications approved by the building official.
317.7 The additions, alteration or repair to any existing building are permitted to be prepared in accordance with the structural and nonstructural requirements for a new building as given in the California Building Code, applied to the entire building.
317.8 The requirements of ASCE 41 Chapters 14 and 15 are to apply to the use of seismic isolation and passive energy systems, respectively, for the repair, voluntary lateral-force-resisting system modification or retrofit of an existing structure. When seismic isolation or passive energy dissipation is used, the project must have project peer review as prescribed in Section 322.
317.9 Any construction required by this chapter shall include structural observation by the registered design professional who is responsible for the structural design in accordance with Section 319.10.
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317.10 Where Method B of Section 321 is used or is required by Section 319.7, the proposed method of building evaluation and design procedures must be accepted by the building official prior to the commencement of the work.
317.11 Voluntary lateral-force-resisting system modifications. Where the exception of Section 317.2 applies, modifications of existing structural components and additions of new structural components that are initiated for the purpose of improving the seismic performance of an existing structure and that are not required by other portions of this chapter are permitted under the requirements of Section 319.12.
SECTION 318 [BSC, DSA-SS & DSA-SS/CC]—DEFINITIONS
318.1 In addition to the definitions given in Section 202, for the purposes of Sections 317 through 323, certain terms are defined as follows:
[DSA-SS & DSA-SS/CC] For the purposes of Section 317 through 323, definitions of terms given in Section 4-207 or 4-314 of the California Administrative Code govern over those in Section 202.
ADDITION [BSC] means any work that increases the floor or roof area or the volume of enclosed space of an existing building, and is structurally attached to the existing building by connections that are required for transmitting vertical or horizontal loads between the addition and the existing structure.
CEBC § 319.10.2 High relevance — show source text
319.10.2 Preconstruction meeting. A preconstruction meeting is mandatory for all projects which require structural observation. The meeting shall include, but is not limited to, the registered design professional, structural observer, general constructor, affected subcontractors, the project inspector and a representative of the enforcement agency (designated alternates may attend if approved by the structural observer). The structural observer shall schedule and coordinate this meeting. The purpose of the meeting is to identify and clarify all essential structural components and connections that affect the lateral and vertical load systems and to review scheduling of the required observations for the project’s structural system retrofit.
319.11 Temporary actions. When compatible with the building use, and the time phasing for both use and the retrofit program, temporary shoring or other structural support is permitted to be considered. Temporary bracing, shoring and prevention of falling hazards are permitted to be used to qualify for Item 1 in Section 319.12 that allows inadequate capability in some existing components, as long as the required performance levels given in Section 317 can be provided by the permanent structure. The consideration for such temporary actions shall be noted in the design documents.
319.12 Voluntary modifications to the lateral-force resisting system. Where modifications of existing structural components and additions of new structural components are initiated for the purpose of improving the lateral-force resisting strength or stiffness of an existing structure and they are not required by other sections of this code, then they are permitted to be designed to meet an approved seismic performance criteria provided that an engineering analysis is submitted that follows: 1. The capacity of existing structural components required to resist forces is not reduced, 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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CEBC § 304A.3.5.17 Medium relevance — show source text
Scope: For buildings located in Seismic Design Category F, verification of the interstory lateral displacements, the strength adequacy of the seismic force-resisting system and anchorage to the foundation shall be accomplished using the Nonlinear Dynamic Procedure.
304A.3.5.17 ASCE 41-13 Chapter 15 and 16. Not permitted by OSHPD.
304A.3.6 Modifications to ASCE 41-23. The text of ASCE 41-23 shall be modified as indicated in Sections 304A.3.6.1 through 304A.3.6.9.
304A.3.6.1 ASCE 41-23 Section 2.1. Modify ASCE 41-23 Section 2.1 with the following:
Seismic evaluations shall be performed for performance objective specified in Section 304A.3.4 of this code (CEBC) using proce- dure of this standard (ASCE 41-23) as follows:
1. Structural components shall be evaluated in accordance with Tier 3 systematic evaluations procedure in Chapter 6.
2. Nonstructural components shall be evaluated in accordance with Chapter 13.
Exception: For general acute care hospitals, seismic evaluation shall be permitted to be in accordance with Chapter 6 of the California Administrative Code (CAC) when required by provisions of that chapter.
304A.3.6.2 ASCE 41-23 Section 6.2. Modify ASCE 41-23 Section 6.2 with the following:
Data Collection Requirements. The extent of data collection shall be at Comprehensive level for all structures, including struc- tures upgraded to SPC-4D. A testing program for materials properties shall be approved by the enforcement agent prior to commencement of material testing work. Previously approved material test results shall be permitted to be used to satisfy part of the comprehensive data collection requirements.
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Tension testing of reinforcing bars shall be in accordance with ASTM A615. All test specimens shall be the full section of the bar as rolled (8-in. gage length) and shall not be reduced.
At test sample locations, structural members, slabs and walls shall be repaired to a state that is equivalent to their original condition.
For buildings built under an OSHPD permit based on the 1976 or later edition of the CBC, where materials properties are shown on design drawings and original materials test data are available, no materials testing shall be required when approved by the enforcement agent.
304A.3.6.3 ASCE 41-23 Section 7.2.9.1. Modify ASCE 41-23 Section 7.2.9.1 with the following:
For the evaluation of one-story light-framed walls with or without hold-downs, ASCE 41-23 Equation 7-6 is permitted to be used. If Equation 7-6 is satisfied, no further evaluation or retrofit of the existing hold-down, if any, is required. If Equation 7-6 is not _satisfied, hold-down shall be provided or retrofitted using ASCE 41-23 Equations 7-39 and 7-40.
CEBC § 3-17 Medium relevance — show source text
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317.10 Where Method B of Section 321 is used or is required by Section 319.7, the proposed method of building evaluation and design procedures must be accepted by the building official prior to the commencement of the work.
317.11 Voluntary lateral-force-resisting system modifications. Where the exception of Section 317.2 applies, modifications of existing structural components and additions of new structural components that are initiated for the purpose of improving the seismic performance of an existing structure and that are not required by other portions of this chapter are permitted under the requirements of Section 319.12.
SECTION 318 [BSC, DSA-SS & DSA-SS/CC]—DEFINITIONS
318.1 In addition to the definitions given in Section 202, for the purposes of Sections 317 through 323, certain terms are defined as follows:
[DSA-SS & DSA-SS/CC] For the purposes of Section 317 through 323, definitions of terms given in Section 4-207 or 4-314 of the California Administrative Code govern over those in Section 202.
ADDITION [BSC] means any work that increases the floor or roof area or the volume of enclosed space of an existing building, and is structurally attached to the existing building by connections that are required for transmitting vertical or horizontal loads between the addition and the existing structure.
ALTERATION [BSC] means any change within or to an existing building, which does not increase and may decrease the floor or roof area or the volume of enclosed space.
BSE-C RESPONSE ACCELERATION PARAMETERS [BSC] are the parameters (S XS and S X1 ) taken from 5-percent/50-year maximum direction spectral response acceleration curves or by a Site Specific Response Spectrum developed in accordance with ASCE 41, Section 2.3.3.
BSE-R RESPONSE ACCELERATION PARAMETERS [BSC] are the parameters (S XS and S X1 ) taken from 20-percent /50-year maximum direction spectral response acceleration curves or by a Site Specific Response Spectrum developed in accordance with ASCE 41, Section 2.3.3.
SECTION 319 [BSC, DSA-SS & DSA-SS/CC]—SEISMIC CRITERIA SELECTION FOR EXISTING BUILDINGS
319.1 Basis for evaluation and design. This section determines what technical approach is to be used for the seismic evaluation and design for existing buildings. For those buildings or portions of buildings for which Section 317 requires action, the procedures and limitations for the evaluation of existing buildings and design of retrofit systems and/or repair thereof shall be implemented in accordance with this section.
One of the following approaches must be used: 1. Method A of Section 320;
2. Method B of Section 321, with independent review of a peer reviewer as required in Section 322; or 3. For state-owned buildings only, the use of one of the specific procedures listed in Section 319.1.1.
CEBC § 1.5. Medium relevance — show source text
Exception: Components required for life-safety purposes after an earthquake, including emergency and standby power systems, mechanical smoke removal systems, fire protection sprinkler systems, fire alarm control panels and egress stairways shall have a component importance factor (I p ) of 1.5.
304A.3.1.2 Major structural alteration, additions or repairs. Major structural alterations, additions or repairs shall be in accor- dance with Section 304A.3.4.1 or 304A.3.4.3 as applicable.
304A.3.2 Seismic evaluation and retrofit of general acute care hospitals for compliance with the California Administrative Code, Chapter 6. Notwithstanding any other requirements of this code, existing general acute care hospitals shall comply with the seismic evaluation requirements specified in Chapter 6, of the California Administrative Code, when applicable. Seismic retrofit to comply with requirements specified in Chapter 6 of the California Administrative Code shall be permitted to be in accordance with these provisions. When load combinations which do not include seismic forces are required, the new building provisions of this code shall be applicable.
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304A.3.3 SPC-4D. Nonconforming hospital buildings satisfying the following requirements and one of Sections 501A.3.1, 501A.3.2 or 304A.3.4.5, but not a combination thereof, shall be considered to satisfy the requirements of SPC-4D. 1. Approval of construction documents based on building characterization in accordance with the California Administrative Code (CAC) Chapter 6 Section 2.1.2.1, material properties in accordance with the CAC Chapter 6 Section 2.1.2.2 and Section 304A.5.3 of this code, and a complete rational structural analysis shall be required. 2. Where the SPC-4D upgrade involves construction, a building permit prior to construction shall be required. 3. Where multiple building permits are used to upgrade a building to SPC-4D, a complete rational structural analysis to justify compliance with SPC-4D, for the building in its final configuration, shall be submitted as part of the construction documents submittal to the Office for the last project. 4. Where the SPC-4D upgrade involves construction, buildings shall be assigned to SPC-4D after all projects required for SPC- 4D are closed in compliance.
304A.3.4 Performance objectives of performance-based methods. Except for the modifications as set forth in Sections 304A.3.4, 304A.3.5 (for ASCE 41-13), and 304A.3.6 (for ASCE 41-23) of this code, all additions, alterations, repairs and seismic retrofit to existing structures or portions thereof shall be permitted to be designed in accordance with the provisions of ASCE 41-23.
Use of ASCE 41-13 shall be limited to SPC-2 and SPC-4D buildings only.
CEBC § 317.2 Medium relevance — show source text
317.2 Scope. All alterations, structurally connected additions and/or repairs to existing structures or portions thereof shall, at a minimum, be designed and constructed to resist the effects of seismic ground motions as provided in this section. The structural system shall be evaluated by a registered design professional and, if not meeting or exceeding the minimum seismic design performance requirements of this section, shall be retrofitted in compliance with these requirements.
Exception: Those structures for which Section 317.3 determines that assessment is not required, or for which Section 317.4 determines that retrofit is not needed, then only the requirements of Section 317.11 apply.
317.3 Applicability.
317.3.1 Existing state-owned buildings. [BSC, DSA-SS] For existing state-owned structures including all buildings owned by the University of California and the California State University, the requirements of Section 317 apply whenever the structure is to be retrofitted, repaired or modified and any of the following apply: 1. Total construction cost, not including cost of furnishings, fixtures and equipment, or normal maintenance, for the building exceeds 25 percent of the construction cost for the replacement of the existing building. The changes are cumulative for past modifications to the building that occurred after adoption of the 1995 California Building Code and did not require seismic retrofit.
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2. There are changes in risk category. 3. The modification to the structural components increases the seismic forces in or strength requirements of any structural component of the existing structure by more than 10 percent cumulative since the original construction, unless the component has the capacity to resist the increased forces determined in accordance with Section 319. If the building’s seismic base shear capacity has been increased since the original construction, the percent change in base shear may be calculated relative to the increased value.
4. Structural elements need repair where the damage has reduced the lateral-load-resisting capacity of the structural system by more than 10 percent. 5. Changes in live or dead load increase story shear by more than 10 percent.
317.3.2 Public school buildings. [DSA-SS] For public schools, the provisions of Section 317 apply when required in accordance with Sections 4-307 and 4-309(c) of the California Administrative Code.
317.3.3 Community college buildings. [DSA-SS/CC] For community colleges, the provisions of Section 317 apply when required in accordance with Sections 4-307 and 4-309(c) of the California Administrative Code.
317.4 Evaluation required. If the criteria in Section 317.3 apply to the project under consideration, the design professional of record shall provide an evaluation in accordance with Section 317 to determine the seismic performance of the building in its current configuration and condition. If the structure's seismic performance as required by Section 317.5 is evaluated as satisfactory and the peer reviewer(s), when Method B of Section 321 is used, concur, then no structural retrofit is required.
_**317.5 Minimum seismic design performance levels for structural and nonstructural components.
CEBC § 8-706 Medium 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:
- The forces need not exceed 0.75 times the seismic forces prescribed by the regular code requirements.
- 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.
- For Risk Category I or II structures, the seismic base shear need not exceed 0.30W.
- 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:
- 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.
- 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.
CEBC § 304A.3.5.13 Medium relevance — show source text
304A.3.5.13 ASCE 41-13 Section 10.7.1.1. Modify ASCE 41-13 Section 10.7.1.1 with the following:
Monolithic Reinforced Concrete Shear Walls and Wall Segments. For nonlinear procedures, shear walls or wall segments with axial loads greater than 0.35 Po shall be included in the model as primary elements with appropriate strength and stiffness degrading properties assigned to those components subject to the approval of the enforcement agent. For linear procedures, the effects of deformation compatibility shall be investigated using moment-curvature section analyses and cyclic testing results of similar components to determine whether strengthening is necessary to maintain the gravity load-carrying capacity of that component.
Horizontal wall segments or spandrels reinforced similar to vertical wall segments or piers shall be classified as wall segments, not shear wall coupling beams, in Tables 10-19 through 10-22.
304A.3.5.14 ASCE 41-13 Section 10.12.3 Modify ASCE 41-13 Section 10.12.3 as follows:
Exception: Component actions that are deformation controlled are permitted to use their expected strengths for the accep- tance criteria.
304A.3.5.15 ASCE 41-13 Section 11.1. Modify ASCE 41-13 Section 11.1 by the following:
Scope: Unreinforced masonry walls (including unreinforced infill walls) and partitions are not permitted for General Acute Care (GAC) hospital buildings.
304A.3.5.16 ASCE 41-13 Section 14.1. Modify ASCE 41-13 Section 14.1 by the following:
Scope: For buildings located in Seismic Design Category F, verification of the interstory lateral displacements, the strength adequacy of the seismic force-resisting system and anchorage to the foundation shall be accomplished using the Nonlinear Dynamic Procedure.
304A.3.5.17 ASCE 41-13 Chapter 15 and 16. Not permitted by OSHPD.
304A.3.6 Modifications to ASCE 41-23. The text of ASCE 41-23 shall be modified as indicated in Sections 304A.3.6.1 through 304A.3.6.9.
304A.3.6.1 ASCE 41-23 Section 2.1. Modify ASCE 41-23 Section 2.1 with the following:
Seismic evaluations shall be performed for performance objective specified in Section 304A.3.4 of this code (CEBC) using proce- dure of this standard (ASCE 41-23) as follows:
1. Structural components shall be evaluated in accordance with Tier 3 systematic evaluations procedure in Chapter 6.
2. Nonstructural components shall be evaluated in accordance with Chapter 13.
Exception: For general acute care hospitals, seismic evaluation shall be permitted to be in accordance with Chapter 6 of the California Administrative Code (CAC) when required by provisions of that chapter.
304A.3.6.2 ASCE 41-23 Section 6.2. Modify ASCE 41-23 Section 6.2 with the following:
CEBC § 12.3 Medium relevance — show source text
APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS
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.
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.
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.
With reference to ASCE 7, Table 12.2-1, ordinary, intermediate and special steel systems, and all light-frame systems shall be permitted without limitation where those systems are used only for retrofit to comply with the requirements of this chapter.
[BS] A403.3.1 Expected story strength. Despite any other requirement of Section A403.3 or A403.4, the total expected strength of retrofit elements added to any story need not exceed 1.7 times the expected strength of the story immediately above in a twostory building, or 1.3 times the expected strength of the story immediately above in a three-story or taller building, as long as the retrofit elements are located symmetrically about the center of mass of the story above, or so as to minimize torsion in the retrofitted story. Calculation of expected story strength and identification of irregularities in Section A403.3 shall be based on the expected strength of all wall lines, even if sheathed with nonconforming materials. The strength of a wall line above the retrofitted story shall be permitted to be reduced to account for inadequate load path or overturning resistance.
[BS] A403.3.2 Seismicity parameters, site class and geologic hazards. For any site designated as Site Class E, the value of F shall be taken as 1.2. Site-specific procedures are not required for compliance with this chapter. Mitigation of existing geologic site hazards such as liquefiable soil, fault rupture or landslide is not required for compliance with this chapter.
Frequently asked questions
Can I do a voluntary seismic upgrade and ignore CEBC retrofit triggers?
No. Voluntary upgrades are allowed under § 319.12, but if your project meets mandatory‑retrofit triggers in § 317.3, you must follow the evaluation/retrofit requirements of Section 317. Check applicability first .
May I remove an existing brace if I add a new shear wall?
Possibly — but § 319.12 requires that you not increase lateral demand beyond component capacity, and any reduction in an existing component’s capacity is only allowed if it satisfies the demonstration tied to § 319.8. All detailing must meet CBC requirements .
Are ASCE 41 Tier 1/Tier 2 procedures acceptable for voluntary work?
Yes — the code pre‑approves ASCE 41 Tier 1 and Tier 2 deficiency‑only procedures where Section 317.3 does not require a full assessment, per § 319.12 .
What must state‑owned building design documents include?
When using § 319.12 for state‑owned buildings, approved design documents must clearly state the scope and acceptance criteria and include the required statement that the CEBC seismic evaluation/strengthening requirements were not checked for this voluntary scope (see § 319.12.1 and § 319.12.1.1) .
Does voluntary mean no inspection or structural observation?
No. Structural observation, inspection and testing requirements in the CEBC (e.g., § 319.10) still apply to construction associated with structural modifications, including voluntary work, as applicable .
More in California Existing Building Code
- Administration and Definitions (Scope, enforcement, code official duties, definitions)
- Provisions for All Compliance Methods (general requirements that apply to all compliance options; Chapter 3 / 3A)
- Seismic retrofit and evaluation (Appendix A and seismic provisions/sections for evaluation and retrofit)
- Referenced Standards and Appendices (Chapter 16 and Appendices A–E, Resource A)
- Repairs (Chapter 4 — repair-specific rules for materials, means of egress, structural, MEP, etc.)
- Alterations — Level 1, Level 2, Level 3 (technical requirements for each alteration level; Chapters 7–9)
- Change of Occupancy and Additions (requirements for occupancy changes and additions; Chapters 10–11)
- Compliance Methods — Prescriptive, Work Area, Performance (Chapters 5, 6–11, 13)
- Relocated Buildings (requirements for buildings moved or relocated; Chapter 14)
- Construction Safeguards (site safety, means of egress and life-safety during construction; Chapter 15)
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