CEBC · California Existing Building Code

When must structural evaluation or upgrades be performed for Level 3 alterations?

If your project is a Level 3 alteration (Chapter 9), Section 906 applies; when the work materially changes the building’s structural system — i.e., is a “substantial structural alteration” — the CEBC requires a registered design professional to evaluate the lateral load‑resisting system and, if it does not meet the referenced California Building Code/CEBC criteria, design and construct the necessary retrofit.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

When a project is a Level 3 alteration, the structural provisions of Chapter 9 apply and the code explicitly directs actions for building elements and the structural system. The CEBC makes clear that the provisions in § 906.1 apply to Level 3 work and that where the work constitutes a substantial structural alteration the building’s lateral system must be shown to meet the referenced requirements (see § 906.1 and § 906.2).

The single most important rule: If your project is a Level 3 alteration, apply Section 906 — and if the work is a substantial structural alteration, you must evaluate (and if necessary upgrade) the lateral load‑resisting system so it satisfies the referenced seismic and lateral-load requirements.

Requirements in detail

Applicability (the trigger)

  • Level 3 alteration: the CEBC directs Chapter 9 requirements to Level 3 projects (see § 901.1 and the Chapter 9 scope); Chapter 9 is the governing chapter for Level 3 work and § 906.1 says this section applies where Level 3 alterations occur. § 906.1 (General) is the starting point.

  • When a structural evaluation/upgrade is required: where the work involves a substantial structural alteration, the lateral load‑resisting system of the altered building must be shown to satisfy the California Building Code requirements referenced in CEBC § 906.2 (see next subsection). In other words: substantial structural alteration → demonstrate compliance (or retrofit) of the lateral system.

What must be shown / done

  • Show the altered building’s lateral system satisfies CBC requirements (e.g., § 1609 referenced in CEBC) and CEBC § 304.3.2 (as required by § 906.2). If it does not, retrofit work is required.
  • For buildings in Seismic Design Category D or F, supports and attachments for nonstructural components that serve any portion of the building with a use in Risk Category IV must comply with CBC § 1613 or ASCE 41 objective of Position Retention at the BSE‑1E hazard level. This requirement is called out in § 906.2.

Decision table — quick reference

Decision dimension What to check Required action Code Reference
Is the project a Level 3 alteration? Level 3 work per Chapter 9 (see scope) Apply Chapter 9 requirements including Section 906 § 906.1
Does the work constitute a “substantial structural alteration”? Is the structural system being substantially altered (see project scope/contract documents and design professional opinion)? Demonstrate lateral system compliance with CBC § 1609 and CEBC § 304.3.2; retrofit if not compliant § 906.2
Building SDC = D or F and part of Risk Category IV use? Building assigned SDC D or F and nonstructural components serve Risk Category IV areas Comply with CBC § 1613 or ASCE 41 (Position Retention, BSE‑1E) for attachments/anchors § 906.2
Existing stairways / vertical openings in work area Stairways used as egress that are part of the work area Enclose stairways from highest work-area floor to exit discharge per requirements § 903.1
Party walls in attached dwellings (Group R‑3) Work area in attached dwelling or townhouse Provide continuous fire separation through concealed floor spaces unless finishes are not removed § 903.2.1

Exceptions and limited-scope cases

  • CEBC provides specific exceptions to the structural triggers. For example, buildings of Group R occupancy with not more than five dwelling or sleeping units altered using conventional light‑frame methods are exempt from some structural requirements in § 906.2. Another exception is when the alteration involves only the lowest story — the lateral system above that story need not comply with § 906.2. See the exceptions in § 906.2 for full wording.

Exceptions & special cases

  • Small residential buildings: Group R, ≤ five dwelling or sleeping units, altered by conventional light‑frame methods may be exempt from the § 906.2 structural showing. § 906.2 — exceptions.
  • Work limited to the lowest story: if alteration affects only the lowest story, elements of the lateral system above that story need not be brought into compliance with § 906.2 (see the exception in § 906.2).
  • Nonstructural anchors / URM: separate CEBC sections require evaluation/anchorage for unreinforced masonry wall, parapets, partitions in certain SDCs (see CEBC § 906.5–906.7 excerpts in the code text). If your building contains URM elements in SDC C–F, evaluation or anchorage may be required tied to other CEBC rules.

Common mistakes

  • Treating Chapter 9 requirements as optional: some designers assume Chapter 9 only adds convenience — in fact § 906.1 makes Section 906 mandatory for Level 3 work.
  • Failing to identify a “substantial structural alteration”: owners/designers sometimes miss that relatively modest changes (e.g., removal or relocation of a shear wall or large openings) can be “substantial” and therefore trigger the lateral‑system showing required by § 906.2.
  • Overlooking nonstructural anchorage triggers: when the building is SDC D or F, anchorage for nonstructural components serving Risk Category IV must meet CBC § 1613 or ASCE 41 Position Retention per § 906.2 — this is commonly missed.
  • Ignoring fire‑separation and shaft rules tied to Level 3: issues like enclosing stairways (per § 903.1) and continuous party‑wall separations in Group R‑3 (per § 903.2.1) are often treated as secondary to structural work but are mandatory Chapter 9 items.

Worked example — concrete scenario

Scenario: A 3‑story, non‑residential building in SDC D is undergoing a renovation that reconfigures 60% of the building area (Level 3) and removes an existing shear wall on the second floor to create an open office.

Steps to check under the CEBC:

  1. Confirm this is a Level 3 alteration (Chapter 9 applies). See § 906.1.
  2. Removal of the shear wall is a substantial structural alteration (it materially changes the lateral system). Under § 906.2, the lateral load‑resisting system of the altered building must be shown to satisfy CBC § 1609 and CEBC § 304.3.2. If the evaluation shows the system does not meet those requirements, retrofit work must be designed and constructed.
  3. Because the building is in SDC D, check attachments/anchors for any nonstructural components serving Risk Category IV uses; comply with CBC § 1613 or ASCE 41 Position Retention as required by § 906.2.
  4. If stair enclosures are affected by the work area, ensure enclosures meet § 903.1 requirements from highest work‑area floor to exit discharge.

Outcome: Structural evaluation by a registered design professional is required; if the lateral system fails the required showing, design retrofit elements (e.g., new shear walls, collectors, connections) to meet the referenced standards and document compliance for plan review per CEBC.

Related provisions

  • § 903.1 — Existing shafts and vertical openings (stairway enclosure requirements for work areas).
  • § 903.2 / § 903.2.1 — Fire partitions in Group R‑3; continuous separation where work is in attached dwelling units/townhouses.
  • § 906.1 — Structural: applicability of Section 906 to Level 3 alterations.
  • § 906.2 — Structural: when a substantial structural alteration triggers lateral system showing, SDC D/F nonstructural anchorage requirements, and listed exceptions.
  • § 904.1 — Automatic sprinkler systems required per California Fire/Building Codes for Level 3 work (related life‑safety upgrades often coordinated with structural work).
  • Sections in Chapter 3 and Sections 317–322 (CEBC) — describe seismic evaluation/retrofit obligations and performance levels applicable to larger or state‑owned projects; relevant where seismic performance assessment is needed.

Code references

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

  • CEBC § 317.2 High 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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    PROVISIONS FOR ALL COMPLIANCE METHODS

    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 § 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 § 906.5 High relevance — show source text

    [BS] 906.5 Anchorage for unreinforced masonry walls. For any building assigned to Seismic Design Category C, D, E or F with a structural system that includes unreinforced masonry bearing walls, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the roof line.

    [BS] 906.6 Bracing for unreinforced masonry parapets. Parapets constructed of unreinforced masonry in buildings assigned to Seismic Design Category C, D, E or F shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of parapet bracing.

    [BS] 906.7 Anchorage of unreinforced masonry partitions. Where the building is assigned to Seismic Design Category C, D, E or F, unreinforced masonry partitions and nonstructural walls within the work area and adjacent to egress paths from the work area shall have their existing conditions evaluated or shall be anchored, removed or altered to resist out-of-plane seismic forces to comply with Section 304.3.2.

    SECTION 907—ENERGY CONSERVATION

    907.1 Minimum requirements. Level 3 alterations to existing buildings or structures shall comply with applicable provisions of the California Energy Code (Part 6, Title 24, C.C.R).

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    ALTERATIONS—LEVEL 3

    SECTION 908—EMERGENCY RESPONDER COMMUNICATIONS ENHANCEMENT SYSTEM COVERAGE

    908.1 Emergency responder communication enhancement system coverage. The existing building shall undergo an evaluation of the emergency responder communication signal strength and coverage area within the entire building in accordance with Sections 908.1.1 and 908.1.2.

    Exception: Where it is determined by the fire code official that the emergency responder communication enhancement system (ERCES) is not needed.

    908.1.1 Evaluation. The evaluation shall determine the current signal strength and coverage capabilities of the public safety communication systems utilized by the jurisdiction, measured at the exterior of the building.

    908.1.2 Compliance. The evaluation report shall be submitted for approval by the fire code official and the frequency license holder. Where the coverage area, signal strength or DAQ does not comply with Section 510 of the California Fire Code, the existing building shall be provided with ERCES coverage. The fire code official is authorized to establish the timeframe for such installation or modification.

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    CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 10 – CHANGE OF OCCUPANCY

    (Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  • CEBC § 902.1 High relevance — show source text

    2 Exception||||†|†|||||||||||||||||||| |902.1_Reserved_|||X|||||||||||||||||||||| |902.2 – 902.2.1|||X|||||||||||||||||||||| |902.2 – 902.3||||†|†|||||||||||||||||||| |903.4||||†|†|||||||||||||||||||| |904.1|||X|||||||||||||||||||||| |904.2|||X|||||||||||||||||||||| |904.2.1|||X|||||||||||||||||||||| |908||||†|†||||||||||||||||||||

    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.

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    9 ALTERATIONS—LEVEL 3

    User notes:

    About this chapter : Chapter 9 provides the technical requirements for those existing buildings that undergo Level 3 alterations. The purpose of this chapter is to provide detailed requirements and provisions to identify the required improvements in the existing building elements, building spaces and building structural system. This chapter is distinguished from Chapters 7 and 8 by involving alterations that cover 50 percent or more of the aggregate area of the building. In contrast, Level 1 alterations do not involve space reconfiguration, and Level 2 alterations involve extensive space reconfiguration that does not exceed 50 percent of the building area. Depending on the nature of alteration work, its location within the building, and whether it encompasses one or more tenants, improvements and upgrades could be required for the open floor penetrations, sprinkler system or the installation of additional means of egress such as stairs or fire escapes. At times and under certain situations, this chapter also is intended to improve the safety of certain building features beyond the work area and in other parts of the building where no alteration work might be taking place.

    SECTION 901—GENERAL

    901.1 Scope. Level 3 alterations as described in Section 604 shall comply with the requirements of this chapter.

    901.2 Compliance. In addition to the provisions of this chapter, work shall comply with all of the requirements of Chapters 7 and 8. The requirements of Sections 802, 803, 804 and 805 shall apply within all work areas whether or not they include exits and corridors shared by more than one tenant and regardless of the occupant load.

    Exception: Buildings in which the reconfiguration of space affecting exits or shared egress access is exclusively the result of compliance with the accessibility requirements of Section 306.7.1 shall not be required to comply with this chapter.

    SECTION 902—SPECIAL USE AND OCCUPANCY

    902.1 Reserved.

    902.2 Group R-2.1 occupancies. Group R-2.1 occupancies shall be classified in accordance with Section 308.2 of the California Build- ing Code .

  • CEBC § 317.3.2 High relevance — show source text

    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. Following the notations of ASCE 41, the seismic requirements for design and assessment are based upon a prescribed Seismic Hazard Level (BSE-1N, BSE-2N, BSE-1E, BSE-R or BSE-C), a specified structural performance level (S-1 through S-5) and a nonstructural performance level (N-A through N-E). The minimum seismic performance criteria are given in Table 317.5 according to the Building Regulatory Authority and the Risk Category as determined in Chapter 16 of the California Building Code or by the regulatory authority. The building shall be evaluated in accordance with a Tier 3 Systematic Evaluation and Retrofit per ASCE 41 Chapter 6 for both the Level 1 and Level 2 performance levels, and the more restrictive requirements shall apply.

    Exception: If the floor area of an addition is greater than the larger of 50 percent of the floor area of the original building or 1,000 square feet (93 m [2] ), then the Table 317.5 entries for BSE-R (or BSE-1E) and BSE-C are replaced by BSE-1N and BSE-2N, respectively.

    |TABLE 317.5—SEISMIC PERFORMANCE REQUIREMENTS2,

  • CEBC § 904.1 High relevance — show source text

    904.1 Automatic sprinkler systems. An automatic sprinkler system shall be provided in accordance with Section 903 of the California Building and California Fire Codes.

    904.2 Fire alarm and detection systems. Fire alarm and detection shall be provided in accordance with Section 907 of the California Building Code as required for new construction in accordance with California Fire Code Sections 907 and 1103.7.

    904.2.1 Systems out of service. Existing fire alarm and detection systems shall be maintained in accordance with Section 901.7 of the California Fire Code. Site fire protection during construction shall be in accordance with Chapter 33 of the California Building and California Fire Codes.

    SECTION 905—MEANS OF EGRESS

    905.1 General. The means of egress shall comply with the requirements of Section 804 except as specifically required in Sections 905.2 and 905.3.

    905.2 Means-of-egress lighting. Means of egress from the highest work area floor to the floor of exit discharge shall be provided with artificial lighting within the exit enclosure in accordance with the requirements of the California Building Code .

    905.3 Exit signs. Means of egress from the highest work area floor to the floor of exit discharge shall be provided with exit signs in accordance with the requirements of the California Building Code .

    905.4 Two-way communications systems. In buildings with elevator service, a two-way communication system shall be provided where required by Section 1009.8 of the California Building Code .

    SECTION 906—STRUCTURAL

    [BS] 906.1 General. Where buildings are undergoing Level 3 alterations, the provisions of this section shall apply.

    [BS] 906.2 Existing structural elements resisting lateral loads. Where work involves a substantial structural alteration,the lateral load-resisting system of the altered building shall be shown to satisfy the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Where the building is assigned to Seismic Design Category D or F, supports and attachments for nonstructural components required to serve any portion of the building with a use included in Risk Category IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

    Exceptions:

    1. Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes that are altered based on the conventional light-frame construction methods of the California Building Code or in compliance with the provisions of the California Residential Code .
    2. Where the intended alteration involves only the lowest story of a building, structural components of the lateral load resisting system above that story need not comply with this section.

    [BS] 906.3 Seismic Design Category F. Where the building is assigned to Seismic Design Category F, the lateral force-resisting system of the altered building shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Supports and attachments for nonstructural components serving any portion of the building with a use included in Risk Cate- gory IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

  • CEBC § 317.1.2.1 High relevance — show source text

    The provisions of Section 317 through 323 also establish minimum standards for earthquake evaluation and design for rehabilitation of existing public buildings currently under the jurisdiction of DSA-SS.

    317.1.2.1 Reference to other chapters. For public schools, where reference within this chapter is made to sections in Chapters 16, 17, 18, 19, 21 or 22 of the California Building Code, the provisions in Chapters 16A, 17A, 18A, 19A, 21A and 22A of the California Building Code, respectively, shall apply instead.

    317.1.3 Community college buildings. [DSA-SS/CC] The provisions of Sections 317 through 323 establish minimum standards for earthquake evaluation and design for the rehabilitation of existing buildings for use as community college buildings under the jurisdiction of the Division of the State Architect—Structural Safety/Community Colleges [DSA-SS/CC], refer to Section 1.9.2.2.

    The provisions of Section 317 through 323 also establish minimum standards for earthquake evaluation and design for rehabilitation of existing community college buildings currently under the jurisdiction of DSA-SS/CC.

    317.1.3.1 Reference to other chapters. For community colleges, where reference within this chapter is made to sections in Chapters 17 or 18 of the California Building Code, the provisions in Chapters 17A and 18A of the California Building Code, respectively, shall apply instead.

    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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  • CEBC § 8-702.2 High relevance — show source text

    8-702.2 Nothing in these regulations shall prevent voluntary and partial seismic upgrades when it is demonstrated that such upgrades will improve life safety and when a full upgrade would not otherwise be required.

    SECTION 8-703 — STRUCTURAL SURVEY

    8-703.1 Scope. When a structure or portion of a structure is to be evaluated for structural capacity under the CHBC, it shall be surveyed for structural conditions by an architect or engineer knowledgeable in historical structures. The survey shall evaluate deterioration or signs of distress. The survey shall determine the details of the structural framing and the system for resistance of gravity and lateral loads. Details, reinforcement and anchorage of structural systems and veneers shall be determined and documented where these members are relied on for seismic lateral resistance.

    8-703.2 The results of the survey shall be utilized for evaluating the structural capacity and for designing modifications to the structural system to reach compliance with this code.

    8-703.3 Historical records. Past historical records of the structure or similar structures may be used in the evaluation, including the effects of subsequent alterations.

    SECTION 8-704 — NONHISTORICAL ADDITIONS AND NONHISTORICAL ALTERATIONS

    8-704.1 New nonhistorical additions and nonhistorical alterations which are structurally separated from an existing historical building or structure shall comply with regular code requirements.

    8-704.2 New nonhistorical additions which impose vertical or lateral loads on an existing structure shall not be permitted unless the affected part of the supporting structure is evaluated and strengthened, if necessary, to meet regular code requirements.

    Note: For use of archaic materials, see Chapter 8-8.

    SECTION 8-705 — STRUCTURAL REGULATIONS

    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.

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    STRUCTURAL REGULATIONS

  • 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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    PROVISIONS FOR ALL COMPLIANCE METHODS

  • CEBC § 903.2.1 High relevance — show source text

    903.2.1 Separation required. Where the work area is in any attached dwelling unit in Group R-3 or any multiple single-family dwelling (townhouse), walls separating the dwelling units that are not continuous from the foundation to the underside of the roof sheathing shall be constructed to provide a continuous fire separation using construction materials consistent with the existing wall or complying with the requirements for new structures. Work shall be performed on the side of the dwelling unit wall that is part of the work area.

    Exception: Where alterations or repairs do not result in the removal of wall or ceiling finishes exposing the structure, walls are not required to be continuous through concealed floor spaces.

    903.3 Interior finish. Interior finish in exits serving the work area shall comply with Section 802.4 between the highest floor on which there is a work area to the floor of exit discharge.

    903.4 Enhanced classroom acoustics. In Group E occupancies, where the work area is a Level 3 alteration, enhanced classroom acoustics shall be provided in all classrooms with a volume of 20,000 cubic feet (565 m [3] ) or less. Enhanced classroom acoustics shall comply with the reverberation time in Section 808 of ICC A117.1.

    2025 CALIFORNIA EXISTING BUILDING CODE 9-3

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    ALTERATIONS—LEVEL 3

    SECTION 904—FIRE PROTECTION

    904.1 Automatic sprinkler systems. An automatic sprinkler system shall be provided in accordance with Section 903 of the California Building and California Fire Codes.

    904.2 Fire alarm and detection systems. Fire alarm and detection shall be provided in accordance with Section 907 of the California Building Code as required for new construction in accordance with California Fire Code Sections 907 and 1103.7.

    904.2.1 Systems out of service. Existing fire alarm and detection systems shall be maintained in accordance with Section 901.7 of the California Fire Code. Site fire protection during construction shall be in accordance with Chapter 33 of the California Building and California Fire Codes.

    SECTION 905—MEANS OF EGRESS

    905.1 General. The means of egress shall comply with the requirements of Section 804 except as specifically required in Sections 905.2 and 905.3.

    905.2 Means-of-egress lighting. Means of egress from the highest work area floor to the floor of exit discharge shall be provided with artificial lighting within the exit enclosure in accordance with the requirements of the California Building Code .

    905.3 Exit signs. Means of egress from the highest work area floor to the floor of exit discharge shall be provided with exit signs in accordance with the requirements of the California Building Code .

    905.4 Two-way communications systems. In buildings with elevator service, a two-way communication system shall be provided where required by Section 1009.8 of the California Building Code .

    SECTION 906—STRUCTURAL

    [BS] 906.1 General. Where buildings are undergoing Level 3 alterations, the provisions of this section shall apply.

  • CEBC § 319.1.3 Medium relevance — show source text

    319.1.3 For state-owned and community college buildings, where unreinforced masonry is not bearing, it may be used only to resist applied lateral loads. Where unreinforced masonry walls are part of the structure they must be assessed for stability under the applicable nonstructural evaluation procedure.

    319.1.4 Public schools. [DSA-SS] For public schools, unreinforced masonry shall not be used to resist in-plane or out-of-plane seismic forces or superimposed gravity loads.

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    PROVISIONS FOR ALL COMPLIANCE METHODS

    319.1.5 Public schools. [DSA-SS] Wood horizontal diaphragms and wood vertical shear walls shall consist of either diagonal lumber sheathing or structural panel sheathing. Braced horizontal diaphragms may be acceptable when approved by DSA. Straight lumber sheathing may be used as diaphragms or shear walls only when overlain with structural panel sheathing. Let-in bracing, plaster (stucco), hollow clay tile, gypsum wallboard and particleboard sheathing shall not be relied upon to resist seismic forces.

    319.2 Existing conditions. The existing condition and properties of the entire structure must be determined and documented by thorough inspection of the structure and site, review of all available related construction documents, review of geotechnical and engineering geologic reports, and performance of necessary testing and investigation. Where samples from the existing structure are taken or in situ tests are performed, they shall be selected and interpreted in a statistically appropriate manner to ensure that the properties determined and used in the evaluation or design are representative of the conditions and structural circumstances likely to be encountered in the structure as a whole. Adjacent structures or site features that may affect the retrofit design shall be identified.

    The entire load path of the seismic-force-resisting system shall be determined, documented and evaluated. The load path includes all the horizontal and vertical elements participating in the structural response: such as diaphragms, diaphragm chords, diaphragm collectors, vertical elements such as walls frames, braces; foundations and the connections between the components and elements of the load path. Repaired or retrofitted elements and the standards under which the work was constructed shall be identified.

    Data collection in accordance with ASCE 41 shall meet the following minimum levels: 1. [BSC] For state-owned buildings, the requirements shall be met following the data collection requirements of ASCE 41, Section 6.2.

    2. [DSA-SS, DSA-SS/CC] For public schools and community college buildings constructed in conformance with the Field Act, visual condition assessment and usual material testing is required unless a more extensive level is required by ASCE 41, Section 6.2.

    3. [DSA-SS, DSA-SS/CC] For public schools and community college buildings not constructed in conformance with the Field Act, comprehensive condition assessment and material testing is required, unless a more extensive level is required by ASCE 41, Section 6.2.

    Concrete material requirements and testing for public school and community college buildings shall also comply with Sections 1911A and 1909.5 of the California Building Code, respectively.

  • CEBC § 8-7 Medium relevance — show source text

    12 2025 CALIFORNIA HISTORICAL BUILDING CODE

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    8-7 STRUCTURAL REGULATIONS

    SECTION 8-701 — PURPOSE, INTENT AND SCOPE

    8-701.1 Purpose. The purpose of the CHBC is to provide alternative regulations to the regular code for the structural safety of buildings designated as qualified historical buildings or properties. The CHBC requires enforcing agencies to accept any reasonably equivalent alternatives to the regular code when dealing with qualified historical buildings or properties.

    8-701.2 Intent. The intent of this chapter is to encourage the preservation of qualified historical buildings or structures while providing standards for a minimum level of building performance with the objective of preventing partial or total structural collapse such that the overall risk of life-threatening injury as a result of structural collapse is low.

    8-701.3 Application. The alternative structural regulations provided by Section 8-705 are to be applied in conjunction with the regular code whenever a structural upgrade or reconstruction is undertaken for qualified historical buildings or properties.

    SECTION 8-702 — GENERAL

    8-702.1 The CHBC shall not be construed to allow the enforcing agency to approve or permit a lower level of safety of structural design and construction than that which is reasonably equivalent to the regular code provisions in occupancies which are critical to the safety and welfare of the public at large, including, but not limited to, public and private schools, hospitals, municipal police and fire stations and essential services facilities.

    8-702.2 Nothing in these regulations shall prevent voluntary and partial seismic upgrades when it is demonstrated that such upgrades will improve life safety and when a full upgrade would not otherwise be required.

    SECTION 8-703 — STRUCTURAL SURVEY

    8-703.1 Scope. When a structure or portion of a structure is to be evaluated for structural capacity under the CHBC, it shall be surveyed for structural conditions by an architect or engineer knowledgeable in historical structures. The survey shall evaluate deterioration or signs of distress. The survey shall determine the details of the structural framing and the system for resistance of gravity and lateral loads. Details, reinforcement and anchorage of structural systems and veneers shall be determined and documented where these members are relied on for seismic lateral resistance.

    8-703.2 The results of the survey shall be utilized for evaluating the structural capacity and for designing modifications to the structural system to reach compliance with this code.

    8-703.3 Historical records. Past historical records of the structure or similar structures may be used in the evaluation, including the effects of subsequent alterations.

    SECTION 8-704 — NONHISTORICAL ADDITIONS AND NONHISTORICAL ALTERATIONS

    8-704.1 New nonhistorical additions and nonhistorical alterations which are structurally separated from an existing historical building or structure shall comply with regular code requirements.

    8-704.2 New nonhistorical additions which impose vertical or lateral loads on an existing structure shall not be permitted unless the affected part of the supporting structure is evaluated and strengthened, if necessary, to meet regular code requirements.

    Note: For use of archaic materials, see Chapter 8-8.

    SECTION 8-705 — STRUCTURAL REGULATIONS

Frequently asked questions

When is work considered “substantial structural alteration”?

The CEBC uses the phrase without a single numeric test in § 906.2; evaluate this by whether the proposed work materially changes the lateral or gravity‑load path (for example removal of shear walls, large openings, or major foundation changes). If it does, the lateral system showing is required.

Do I always need a seismic retrofit for any Level 3 project?

No — Level 3 projects must follow Section 906, and a structural showing is required when the work is a substantial structural alteration (see § 906.2). If the showing demonstrates the existing lateral system already meets the referenced requirements, a retrofit may not be required.

Who performs the evaluation?

A registered design professional (architect or engineer) is required to evaluate the structural system and prepare the necessary analysis and documents when a structural showing or retrofit is required under Section 906 and related CEBC sections.

Are there residential exceptions?

Yes — Group R buildings with not more than five dwelling or sleeping units altered using conventional light‑frame methods have exceptions to some structural showing requirements in § 906.2.

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Related in the CEBC

What makes an alteration Level 3 and what special occupancy rules apply (R-2.1, ambulatory care)?

When are sprinklers, fire alarm/detection and site fire-protection measures required?

What egress, exit-sign and two-way communications provisions apply for Level 3?

Level 3 technical requirements (Chapter 9)

California Existing Building Code