CEBC · California Existing Building Code

Key definitions for seismic retrofit and evaluation (terms to know)

Q: What if my work both increases floor area and removes some interior partitions — is it an ADDITION or ALTERATION?

If the work increases floor or roof area or enclosed volume and is structurally attached, it is an ADDITION per § 318.1 , even if other parts of the building are reduced.

Q: Does the CEBC definition list replace Section 202 definitions?

No — § 318.1 provides definitions specific to Sections 317–323 and supplements Section 202. For DSA‑regulated projects, the California Administrative Code definitions (Sections 4‑207 or 4‑314 ) govern over Section 202 for these sections.

Q: I can’t find a term here that I need. Where should I look?

If the needed term isn’t in § 318.1 , check CEBC Section 202 , the California Administrative Code sections noted in § 318.1 , or the referenced standards (ASCE 41) as appropriate. The retrieved CEBC excerpt contains only the definitions shown in § 318.1 ; other terms are outside that excerpt.

This page explains the CEBC definitions you must use for seismic evaluation and retrofit decisions: **ADDITION** (any increase in floor/roof area or enclosed volume that is structurally attached), **ALTERATION** (changes that do not increase area/volume), and the **BSE‑C/BSE‑R** spectral parameter sets (SXS, SX1 taken from 5%/50‑yr or 20%/50‑yr curves). Use **§ 318.1** as the primary source and consult the referenced CEBC sections and ASCE 41 for how those definitions affect evaluation and retrofit requirements.

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Last reviewed: July 6, 2026

What the code requires

The California Existing Building Code (CEBC) collects specific definitions that control how an existing building is evaluated and when seismic retrofit is required. The controlling definitions for Sections 317–323 are located in § 318.1 and must be used to interpret terms such as ADDITION, ALTERATION, and the seismic hazard parameter sets (BSE‑C and BSE‑R) that feed ASCE 41-based evaluations and retrofit decisions. See § 318.1 for these definitions and the note on which administrative-code definitions govern for DSA projects.

The single most important rule: use the CEBC definitions in § 318.1 to decide whether work is an ADDITION or ALTERATION and to identify which spectral parameters (BSE‑C vs. BSE‑R) apply to your seismic evaluation.

Requirements in detail

Key defined terms (first-mention bolded)

ADDITION — Any work that increases the floor or roof area or the volume of enclosed space of an existing building and is structurally attached such that vertical or horizontal loads are transmitted between new and existing portions. § 318.1 defines this for use in Sections 317–323.
ALTERATION — Any change within or to an existing building that does not increase (and may decrease) floor/roof area or enclosed volume. See § 318.1.
BSE‑C RESPONSE ACCELERATION PARAMETERS — The pair of site spectral parameters (SXS and SX1) taken from the 5‑percent/50‑year maximum‑direction spectral response curves or a site‑specific response spectrum developed per ASCE 41, Section 2.3.3. These parameters are used when the CEBC requires the BSE‑C seismic hazard level. § 318.1.
BSE‑R RESPONSE ACCELERATION PARAMETERS — The pair SXS and SX1 taken from the 20‑percent/50‑year maximum‑direction spectral response curves or a site‑specific spectrum per ASCE 41, Section 2.3.3. Use when the CEBC requires the BSE‑R hazard level. § 318.1.

Decision‑relevant table

Decision item	Key value / trigger	What it controls	Code reference
Is the work an ADDITION?	Any increase in floor/roof area or enclosed volume; structural attachment transmits loads	Determines whether addition rules (and possible stricter seismic criteria) apply	§ 318.1
Is the work an ALTERATION?	Any change that does not increase floor/roof area or volume (may decrease)	Determines applicability of alteration provisions vs. addition provisions	§ 318.1
Choose spectral parameters	BSE‑C: 5‑percent/50‑year curves (SXS, SX1). BSE‑R: 20‑percent/50‑year curves (SXS, SX1)	Controls the ground motion input for ASCE 41 evaluation / retrofit design	§ 318.1 and ASCE 41 reference in CEBC
Which definitions control DSA projects	Definitions in CAC § 4‑207 or § 4‑314 govern over CEBC Section 202 for Sections 317–323	Use the administrative‑code definitions for DSA‑regulated buildings	§ 318.1

How these definitions affect the evaluation/retrofit workflow

Determining whether scope is an ADDITION or ALTERATION affects which seismic criteria and performance levels (Table 317.5 and related Sections) apply during evaluation and whether retrofit is required. See CEBC Sections 317 and 319 for the downstream consequences.
Selecting BSE‑C vs. BSE‑R fixes the spectral acceleration inputs (SXS, SX1) used in ASCE 41 procedures (Method A or B) required by the CEBC. The CEBC explicitly ties BSE parameters to the stated percent/50‑year curves in § 318.1.

Exceptions & special cases

For projects under DSA (DSA‑SS & DSA‑SS/CC), the CEBC states that the definitions found in the California Administrative Code (Sections 4‑207 or 4‑314) override Section 202 definitions for Sections 317–323. In other words, check those administrative‑code definitions first for DSA‑regulated buildings. § 318.1 .
The CEBC text you provided contains the listed definitions (ADDITION, ALTERATION, BSE‑C, BSE‑R) but does not print every possible term used elsewhere (for example, terms defined in Section 202 or other administrative-code sections). If you need a definition that is not in § 318.1, consult Section 202 or the specific administrative code cited; the retrieved file does not show those additional definitions. .

Common mistakes

Treating an interior increase (e.g., creating a mezzanine) as an ALTERATION when it actually increases enclosed volume or floor area. If floor/roof area or enclosed volume increases, it is an ADDITION per § 318.1.
Using the wrong spectral inputs: using BSE‑C (5‑%/50‑yr) spectra where the project calls for BSE‑R (20‑%/50‑yr) (or vice versa). The CEBC ties each hazard level to a particular spectral curve set; confirm which BSE is required by the applicable CEBC section (e.g., Table 317.5 and Sections 319–321).
Forgetting the DSA override: for DSA projects, definitions from the California Administrative Code may govern — failing to check those will cause misapplication of terms. § 318.1
Assuming other seismic terms (m‑factor, performance levels S‑1..S‑5, etc.) are defined here — many are defined or explained elsewhere in CEBC (see Sections 317 and ASCE 41 references). Always cite the controlling section for that specific concept.

Worked example — applying the definitions with numbers (illustrative)

Scenario: You are designing work on a 5,000 ft² office building. The owner proposes to enclose an existing rooftop open area and add a 700 ft² mechanical room connected to the building structure.

Does this count as an ADDITION?
- The proposal increases floor/roof area by 700 ft² (an increase > 0). Under § 318.1, any work that increases floor or roof area or enclosed volume and is structurally attached is an ADDITION. So this is an ADDITION (not merely an alteration). § 318.1 .
What seismic hazard parameters do you use for evaluation? (illustrative numbers)
- Suppose the CEBC Table 317.5 or your project’s risk category requires BSE‑C. You would extract SXS and SX1 from the 5‑percent/50‑year spectral curves for your site (for example, hypothetically SXS = 0.80 g, SX1 = 0.32 g) and use those as the ground‑motion inputs into ASCE 41 evaluation per the CEBC requirement that BSE‑C parameters come from the 5‑percent/50‑year curves. The CEBC defines this origin for the parameters in § 318.1; the numeric SXS/SX1 values are site specific and must come from the referenced spectral curves or a site‑specific response spectrum. § 318.1 .
Consequence for design path: Because the work is an ADDITION, check Section 317 and Section 319 to determine whether the addition triggers a seismic evaluation or retrofit requirement (for example, see how CEBC links performance levels and evaluation methods in Sections 317 and 319).

Note: the numeric SXS/SX1 values above are illustrative only; use published spectral maps or a site‑specific spectrum per ASCE 41 and CEBC procedure to determine the actual numbers for design. § 318.1

Related provisions

§ 317 — Earthquake evaluation and design for retrofit of existing buildings (performance levels and when retrofit is required).
§ 319 — Seismic criteria selection for existing buildings (how to pick Method A / B and limitations).
§ 320 — Method A (procedures referencing ASCE 41).
§ 321 — Method B (detailed evaluation and peer review requirements).
§ 322 — Peer review requirements (when Method B is used).

Code references

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

CEBC § 31F-77 High relevance — show source text
s = Spacing of hoops or spiral along the pile axis

t = Steel pile wall thickness

Δ = Displacement capacity

θ = Angle of critical crack to the pile axis

θ = Plastic rotation p α = Angle between line joining centers of flexural compression in the deck/pile and in-ground hinges, and the pile axis

φ a = Allowable curvature

φ m = Maximum curvature φ p, φ p,m = Plastic curvature φ u = Ultimate curvature φ ′ u = Adjusted ultimate curvature

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MARINE OIL TERMINALS

φ y = Yield curvature φ ′ y = Adjusted yield curvature

τ = Maximum allowable shear stress capacity τ design = Design shear strength τ max = Maximum shear stress

V c = Concrete shear strength v j = Nominal joint shear stress V design = Design shear strength V max = Maximum shear demand

V n = Nominal shear strength V p = Contribution to shear strength from axial loads V s = Transverse reinforcement shear strength V pile = Shear strength of steel pile

3107F.9 References.

[7.1] Priestley, M.J.N, Seible, F. and Calvi, G.M. “Seismic Design and Retrofit of Bridges,” 1996, New York.

[7.2] Ferritto, J., Dickenson, S., Priestley N., Werner, S., Taylor, C., Burke D., Seelig W., and Kelly, S., 1999, “Seismic Criteria for Califor- nia Marine Oil Terminals, Vol.1 and Vol.2,” Technical Report TR-2103-SHR, Naval Facilities Engineering Service Center, Port Hueneme, CA.

[7.3] American Society of Civil Engineers (ASCE), 2017, ASCE/SEI 41-17 (ASCE/SEI 41), “Seismic Evaluation and Retrofit of Existing Buildings,” Reston, VA.

[7.4] Blakeley, J.P., Park, R., “Prestressed Concrete Sections with Cyclic Flexure,” Journal of the Structural Division, American Society of Civil Engineers, Vol. 99, No. ST8, August1973, pp. 1 71 7-1 742, Reston, VA.

[7.5] American Society of Civil Engineers (ASCE), 2014, ASCE/COPRI 61-14 (ASCE/COPRI 61), “Seismic Design of Piers and Wharves,” Reston, VA.

[7.6] Port of Long Beach (POLB), 2012 February 29, “Wharf Design Criteria,” Version 3.0, Long Beach, CA.

[7.7] American Concrete Institute (ACI), 2014, ACI 318-14 (ACI 318), “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” Farmington Hills, MI.
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 § 3-17 High relevance — show source text
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PROVISIONS FOR ALL COMPLIANCE METHODS

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 § 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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PROVISIONS FOR ALL COMPLIANCE METHODS

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

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

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

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

321.1 The existing or retrofitted structure shall be demonstrated to have the capability to sustain the deformation response due to the specified earthquake ground motions and meet the seismic performance requirements of Section 317. The registered design professional shall provide an evaluation of the response of the existing structure in its modified configuration and condition to the ground motions specified. If the building’s seismic performance is evaluated as satisfactory and the peer reviewer(s) and the enforcement agency concurs, then no further structural retrofit and/or repair of the lateral load-resisting system is required.
CEBC § 1.9.2.1. High relevance — show source text
State-owned and state-leased essential services buildings are subject to the regulatory authority of DSA-SS per Section 1.9.2.1._|1. ASCE 41 provides acceptance criteria (e.g., m-factor, rotation) for Immediate Occupancy (S1), Life Safety (S3) and Collapse Prevention (S5), and specifies in Table 2-1 the method
to interpolate values for S-2 and S-4. When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be
required by ASCE 7 nonstructural provisions for new construction.
2. Buildings evaluated and retrofitted to meet the structural and nonstructural requirements for a new building as given in the California Building Code as adopted by DSA or BSC, as
applicable, are deemed to meet the seismic performance requirements of this section.
3. 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.|1. ASCE 41 provides acceptance criteria (e.g., m-factor, rotation) for Immediate Occupancy (S1), Life Safety (S3) and Collapse Prevention (S5), and specifies in Table 2-1 the method
to interpolate values for S-2 and S-4. When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be
required by ASCE 7 nonstructural provisions for new construction.
2. Buildings evaluated and retrofitted to meet the structural and nonstructural requirements for a new building as given in the California Building Code as adopted by DSA or BSC, as
applicable, are deemed to meet the seismic performance requirements of this section.
3. 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.
CEBC § 3-4 High relevance — show source text
303 Storm Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

304 Structural Design Loads and Evaluation and Design Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

305 In-Situ Load Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

306 Accessibility for Existing Buildings . . . . . . . . . . . . . . . 3-6

307 Smoke Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

308 Carbon Monoxide Detection . . . . . . . . . . . . . . . . . . . . . 3-6

309 Additions and Replacements of Exterior Wall Coverings and Exterior Wall Envelopes . . . . . . . . . 3-7

310 [OSHPD 1R, 2 and 5] Services/Systems and Utilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

311 [OSHPD 1R, 2 and 5] Means of Egress . . . . . . . . . . . . . . . 3-7

312 [OSHPD 1R] Hospital SPC and Freestanding Buildings Removed from General Acute Care Service Remaining under the Jurisdiction of OSHPD . . . . . . . . . . . . . . . . . 3-7

313 [SFM] Existing Group R-1 and Group R-2 Occupancies . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

314 [SFM] Existing High-Rise Buildings . . . . . . . . . . . . . . . .3-11

315 [SFM] Existing Group I Occupancies . . . . . . . . . . . . . . .3-13

316 [SFM] Existing Group L Occupancies. . . . . . . . . . . . . . .3-14

317 [BSC, DSA-SS & DSA-SS/CC] Earthquake Evaluation and Design for Retrofit of Existing Buildings. . . . . . . . . .3-16

318 [BSC, DSA-SS & DSA-SS/CC] Definitions . . . . . . . . . . . .3-18

319 [BSC, DSA-SS & DSA-SS/CC] Seismic Criteria Selection for Existing Buildings . . . . . . . . . . . . . . . . . . . . . . . . . .3-18

320 [BSC, DSA-SS & DSA-SS/CC] Method A. . . . . . . . . . . . . .3-21
CEBC § 405.2.1 High relevance — show source text
[BS] 405.2.1 Repairs for less than substantial structural damage. Unless otherwise required by this section, for damage less than substantial structural damage, the damaged elements shall be permitted to be restored to their predamage condition.

[BS] 405.2.1.1 Snow damage. Structural components whose damage was caused by or related to snow load effects shall be repaired, replaced or altered to satisfy the requirements of Section 1608 of the California Building Code .

[BS] 405.2.2 Disproportionate earthquake damage. A building assigned to Seismic Design Category D, E or F that has sustained disproportionate earthquake damage shall be subject to the requirements for buildings with substantial structural damage to vertical elements of the lateral force-resisting system.

[BS] 405.2.3 Substantial structural damage to vertical elements of the lateral force-resisting system. A building that has sustained substantial structural damage to the vertical elements of its lateral force-resisting system shall be evaluated in accordance with Section 405.2.3.1, and either repaired in accordance with Section 405.2.3.2 or repaired and retrofitted in accordance with Section 405.2.3.3, depending on the results of the evaluation.

Exceptions:
1. Buildings assigned to Seismic Design Category A, B or C whose substantial structural damage was not caused by earthquake need not be evaluated or retrofitted for load combinations that include earthquake effects.
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REPAIRS
1. One- and two-family dwellings need not be evaluated or retrofitted for load combinations that include earthquake effects.
[BS] 405.2.3.1 Evaluation. The building shall be evaluated by a registered design professional, and the evaluation findings shall be submitted to the code official. The evaluation shall establish whether the lateral force-resisting system of the damaged building, including its foundation, if repaired to its predamage state, would comply with the provisions of the California Build- ing Code for load combinations that include wind effects, and with Section 304.3.2 of this code.

[BS] 405.2.3.2 Extent of repair for compliant buildings. If the evaluation establishes that the building in its predamage condition complies with the provisions of Section 405.2.3.1, then the damaged elements shall be permitted to be restored to their predamage condition.

[BS] 405.2.3.3 Extent of repair for noncompliant buildings. If the evaluation does not establish that the lateral force-resisting system of the building in its predamage condition complies with the provisions of Section 405.2.3.1, then the lateral forceresisting system, and its foundation, shall be retrofitted to comply with the provisions of this section. The wind loads for the repair and retrofit shall be those required by the building code in effect at the time of original construction, unless the damage was caused by wind, in which case the wind loads shall be in accordance with the California Building Code . The seismic retrofit shall comply with Section 304.3.2 of this code, but the earthquake loads shall not be less than those required by the building code in effect at the time of original construction.
CEBC § 8-706 High relevance — show source text
SECTION 8-706 — LATERAL LOAD REGULATIONS

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

Exceptions:
1. The forces need not exceed 0.75 times the seismic forces prescribed by the regular code requirements.
2. For Risk Category I, II or III structures, near-fault increases in ground motion (maximum considered earthquake ground motion of 0.2 second spectral response greater than 150 percent at 5 percent damping) need not be considered when the fundamental period of the building is 0.5 seconds in the direction under consideration.
3. For Risk Category I or II structures, the seismic base shear need not exceed 0.30W.
4. For Risk Category III or IV structures, the seismic base shear need not exceed 0.40W.
8-706.1.1 When a building is to be strengthened with the addition of a new lateral force resisting system, the R -value of the new system can be used when the new lateral force resisting system resists at least 75 percent of the building’s base shear regardless of its relative rigidity.

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

Exceptions:
1. Alternative standards may be used on a case-by-case basis when approved by the authority having jurisdiction. It shall be permitted to exceed the strength limitation of 100 psi in Section A108.2 of the CEBC when test data and building configuration supports higher values subject to the approval of the authority having jurisdiction.
2. CEBC Section A102.2 shall not apply to Qualified Historical Buildings in Risk Category III buildings and other structures whose primary occupancies are public assembly with an occupancy load greater than 300.
8-706.1.3 All deviations from the detailing provisions of the lateral-force-resisting systems shall be evaluated for stability and the ability to maintain load-carrying capacity at the expected inelastic deformations.

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

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

8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.
CEBC § 503.12 High relevance — show source text
7—2016 with Supplement 1: Minimum Design Loads and Associated Criteria for Buildings and Other Structures [OSHPD 1] with Supplement 3

503.12, 706.3.2

7—2022: Minimum Design Loads and Associated Criteria for Buildings and Other Structures [OSHPD 1, 1R, 2, 4 and 5, DSS-SS, DSA- SS/CC] with Supplement 1

304.2, 304.3.1, 304A.2, 304A.3.6.4, 304A.3.6.6, 503.4, 503.12, 503.13, 501A.3, 502A.5, 503A.4, 503A.13, 706.3.2, 805.3, 805.4

41— 2013 : [OSHPD 1] Seismic Evaluation and Retrofit of Existing Buildings 304.3.1, Table 304.3.1, 304.3.2, Table 304.3.2, 503.5, 503.11, 506.5.3, 906.2, 906.3, 1006.3

41—2017: Seismic Evaluation and Retrofit of Existing Buildings 304.3.1, Table 304.3.1, 304.3.2, Table 304.3.2, 503.5, 503.11, 506.5.3, 906.2, 906.3, 1006.3

41— 2023 : [BSC, DSA-SS, DSA-SS/CC, HCD, OSHPD 1, 1R, 2, 4 and 5] Seismic Evaluation and Retrofit of Existing Buildings 304.3.1, Table 304.3.1, 304.3.2, Table 304.3.2, 317.5, Table 317.5, 317.8, 318.1, 319.1, 319.2, 319.5, 319.7.7, 319.8, 319.9, 319.12, 320.1, 321.2.2, 304A.3.4, 304A.3.6, 503.5, 503.11, 506.5.3, 506A.5.3, 906.2, 906.3, 1006.3

ASHRAE ASHRAE, 180 Technology Parkway, Peachtree Corners, GA 30092

62.1—2022: Ventilation for Acceptable Indoor Air Quality

807.2

2025 CALIFORNIA EXISTING BUILDING CODE 16-3

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

REFERENCED STANDARDS

ASME American Society of Mechanical Engineers, Two Park Avenue, New York, NY 10016

A17.1—2022/CSA B44—2022: Safety Code for Elevators and Escalators

306.7.7, 306.7.8, 902.1.2

A17.3—2023: Safety Code for Existing Elevators and Escalators

902.1.2
CEBC § 319.1 Medium 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.

2025 CALIFORNIA EXISTING BUILDING CODE 3-17

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

PROVISIONS FOR ALL COMPLIANCE METHODS

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 § 7.12 Medium relevance — show source text
SECTION 303 A — RESERVED

SECTION 304 A —STRUCTURAL DESIGN LOADS AND EVALUATION AND DESIGN PROCEDURES

304 A .1 Live loads. Where an addition or alteration does not result in increased design live load, existing gravity load-carrying structural elements shall be permitted to be evaluated and designed for live loads approved prior to the addition or alteration. If the approved live load is less than that required by Section 1607 A of the California Building Code, the area designated for the nonconforming live load shall be posted with placards of approved design indicating the approved live load. Where the addition or alteration results in increased design live load, the live load required by Section 1607 A of the California Building Code shall be used.

304 A .2 Snow loads on adjacent buildings. Where an alteration or addition changes the potential snow drift effects on an adjacent building, the code official is authorized to enforce Section 7.12 of ASCE 7.

304 A .3 Additions, alterations, repairs and seismic retrofit to existing buildings or structures.

304 A .3.1 Structures designed in accordance with pre-1973 building code. Provisions of this section shall apply to hospital build- ings which were originally designed to pre-1973 building codes and not designated as SPC 3 or higher in accordance with Chapter 6 of the California Administrative Code.

304A.3.1.1 Incidental and minor structural alteration, additions, or repairs. Incidental and minor structural additions shall be permitted, provided the additions meet the California Building Code for new construction using importance factor, I e , equal to or greater than 1.0. Alterations or repair to existing gravity and lateral force-resisting systems shall be made to conform to the requirements of Section 503A or Chapter 4A, respectively, using importance factor, I e , equal to or greater than 1.0. 1. Nonstructural components. Component importance factor, I p , shall be permitted to be 1.0.

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

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

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

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

Exceptions:

Frequently asked questions

What if my work both increases floor area and removes some interior partitions — is it an ADDITION or ALTERATION?

If the work increases floor or roof area or enclosed volume and is structurally attached, it is an ADDITION per § 318.1, even if other parts of the building are reduced.

Where do I get the numeric SXS and SX1 values?

SXS and SX1 are obtained from the specified spectral curves: BSE‑C uses the 5‑percent/50‑year curves and BSE‑R uses 20‑percent/50‑year curves, or from a site‑specific response spectrum developed per ASCE 41, Section 2.3.3, as defined in § 318.1.

Does the CEBC definition list replace Section 202 definitions?

No — § 318.1 provides definitions specific to Sections 317–323 and supplements Section 202. For DSA‑regulated projects, the California Administrative Code definitions (Sections 4‑207 or 4‑314) govern over Section 202 for these sections.

If my project requires Method B, do the definitions change?

The definitions themselves remain the same, but Method B has additional procedural and peer‑review requirements; use the CEBC definitions (including BSE inputs from § 318.1) when performing Method B evaluations (see § 321 and § 322).

I can’t find a term here that I need. Where should I look?

If the needed term isn’t in § 318.1, check CEBC Section 202, the California Administrative Code sections noted in § 318.1, or the referenced standards (ASCE 41) as appropriate. The retrieved CEBC excerpt contains only the definitions shown in § 318.1; other terms are outside that excerpt.

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California Existing Building Code