CEBC · California Existing Building Code
What are the minimum seismic performance levels required?
Table 317.5 of the California Existing Building Code (§ 317.5) tells you the minimum earthquake performance targets — a Seismic Hazard Level (BSE‑...), a structural performance level (S‑1 to S‑5) and a nonstructural level (N‑A to N‑E) — that your building must meet based on the regulatory authority and Risk Category. Large additions (over 50% or 1,000 ft²) change the hazard levels; both Level 1 and Level 2 must be checked with an ASCE 41 Tier 3 evaluation and the stricter result controls.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
The California Existing Building Code requires that existing state, school and community‑college buildings be evaluated and (if necessary) retrofitted to meet the minimum seismic performance criteria prescribed in § 317.5 and Table 317.5. These criteria are stated using ASCE 41 notations: Seismic Hazard Levels (for example BSE‑1N, BSE‑2N, BSE‑C, BSE‑R), structural performance levels (S‑1 through S‑5) and nonstructural performance levels (N‑A through N‑E). The building must be evaluated using a Tier 3 Systematic Evaluation and Retrofit (ASCE 41, Ch. 6) for both the Level 1 and Level 2 performance objectives and the more restrictive result controls.
The single most important rule: Table 317.5 specifies the required Seismic Hazard Level, structural performance level, and nonstructural performance level for a building based on the building regulatory authority and its Risk Category; those targets are the minimum the building must meet.
Requirements in detail
How the requirements are expressed
- The minimum requirements are given as a triplet: (Seismic Hazard Level, Structural performance S‑#, Nonstructural performance N‑#). These use the ASCE 41 nomenclature referenced by § 317.5.
- Evaluations and retrofit designs for those performance levels are performed per ASCE 41 procedures (Tier 3 for Table 317.5 targets) and the more restrictive of the Level 1 and Level 2 outcomes applies. § 317.5 requires Tier 3 evaluation for both levels.
Key numeric thresholds and the exception for large additions
- If an addition’s floor area is greater than the larger of 50 percent of the original building’s floor area or 1,000 square feet, then the Table 317.5 entries that would otherwise be BSE‑R (or BSE‑1E) and BSE‑C are replaced by BSE‑1N and BSE‑2N, respectively. This is an explicit exception in § 317.5.
Decision‑relevant summary table (excerpt of Table 317.5)
Use this table to determine the required performance triplets you must design/evaluate to. Refer to § 317.5 and Table 317.5 for the full official table.
| Building Regulatory Authority | Risk Category | Level 1 (minimum) | Level 2 (minimum) | Code Reference |
|---|---|---|---|---|
| State‑Owned [BSC] | I, II, III | BSE‑R, S‑3, N‑C | BSE‑C, S‑5, N‑D | § 317.5; Table 317.5 |
| State‑Owned [BSC] | IV | BSE‑R, S‑1, N‑B | BSE‑C, S‑3, N‑D | § 317.5; Table 317.5 |
| Division of the State Architect — DSA‑SS | I | BSE‑1N, S‑3, N‑B | BSE‑2N, S‑5, N‑D | § 317.5; Table 317.5 |
| DSA‑SS | II, III | BSE‑1N, S‑2, N‑B | BSE‑2N, S‑4, N‑D | § 317.5; Table 317.5 |
| DSA‑SS | IV | BSE‑1N, S‑1, N‑A | BSE‑2N, S‑3, N‑D | § 317.5; Table 317.5 |
| DSA‑SS/CC (Schools & Community Colleges) | I, II | BSE‑1E, S‑3, N‑C | BSE‑2N, S‑5, N‑D | § 317.5; Table 317.5 |
| DSA‑SS/CC | III | BSE‑1E, S‑3, N‑B | BSE‑2N, S‑5, N‑D | § 317.5; Table 317.5 |
| DSA‑SS/CC | IV | BSE‑1E, S‑1, N‑B | BSE‑2N, S‑3, N‑D | § 317.5; Table 317.5 |
Notes:
- The table above is an excerpt; see Table 317.5 in the CEBC for the full assignment by authority and risk category.
- The terms BSE‑1N, BSE‑2N, BSE‑1E, BSE‑R, BSE‑C, S‑#, N‑# are ASCE 41 notations referenced directly in § 317.5; the CEBC relies on ASCE 41 for definitions of those performance levels.
Exceptions & special cases
- Large addition exception: if the addition floor area > max(50% of original floor area, 1,000 sq ft) then entries of BSE‑R/BSE‑1E and BSE‑C are replaced with BSE‑1N and BSE‑2N, respectively. § 317.5 contains this explicit exception.
- Where nonstructural performance in Table 317.5 is N‑D or higher, mechanical/electrical/plumbing components must comply with ASCE 41, Chapter 13, §13.2 (see § 319.9).
- The code allows a limited exception where a component’s strength may be less than the seismic load combinations require — only if removing or failing that component does not cause the system to fail the required performance objectives (see Section 319.8 exception). That exception prevents treating that component as part of the primary lateral system.
Common mistakes
- Treating Table 317.5 as optional: Table 317.5 is the baseline for minimum required performance triplets for the applicable authority and risk category — it is not guidance only. § 317.5 requires compliance.
- Confusing Level 1 and Level 2: both Level 1 and Level 2 targets must be evaluated via Tier 3 and the more restrictive result controls the retrofit decision (per § 317.5).
- Failing to apply the large‑addition exception: when an addition exceeds 50% or 1,000 ft² the seismic hazard levels in the table change — this substitution is easy to miss.
- Ignoring nonstructural requirements: if Table 317.5 requires N‑D or higher, ASCE 41 Chapter 13 provisions for MEP systems apply (see § 319.9).
- Not using the correct Risk Category: Table 317.5 entries are keyed to Risk Category as determined in CBC Chapter 16 (or by the regulatory authority); misclassification changes the required S/N/BSE targets.
Worked example — concrete scenario
Scenario: A State‑owned building under the Building Standards Commission (BSC) is assigned Risk Category II. The owner plans a large addition equal to 60% of the original floor area.
Step 1 — find the Table targets for the authority & risk category:
- For State‑Owned [BSC], Risk Category I, II, III, Table 317.5 lists Level 1 = BSE‑R, S‑3, N‑C and Level 2 = BSE‑C, S‑5, N‑D.
Step 2 — apply the large‑addition exception (addition = 60% > 50%):
- Because the addition exceeds the larger of 50% or 1,000 ft², BSE‑R and BSE‑C are replaced by BSE‑1N and BSE‑2N, respectively (per § 317.5). The required triplets become:
- Level 1 = BSE‑1N, S‑3, N‑C
- Level 2 = BSE‑2N, S‑5, N‑D.
Step 3 — evaluation and consequence:
- The building must be evaluated per Tier 3 Systematic Evaluation and Retrofit (ASCE 41 Ch. 6) against both Level 1 and Level 2 targets; design professionals must use the more restrictive outcome. If the building fails to meet the required performance objectives, a retrofit compliant with Section 317 retrofit provisions is required.
Related provisions
- § 317.2 — Scope (what work this section applies to).
- § 317.4 — Evaluation required (when a design professional must evaluate performance and when retrofit is not required if satisfactory).
- § 317.6 — Retrofit required (what the owner must do if the building does not meet Table 317.5).
- § 318.1 — Definitions used in Sections 317–323 (includes BSE‑R and BSE‑C definitions/parameters).
- § 319.1 — Basis for evaluation and design (methods available).
- § 319.8 — Strength requirements and the limited component exception.
- § 319.9 — Nonstructural component requirements; triggers for ASCE 41 Ch. 13 compliance.
- § 320 — Method A (ASCE 41 linear procedures referenced for retrofit design).
- § 321 — Method B (performance evaluation approach; peer review and acceptance).
- § 322 — Peer review requirements (applies when Method B or other peer review triggers exist).
Code references
Grounded in the retrieved California Existing Building Code — click a citation to read the verbatim passage:
CEBC § 317.5 High relevance — show source text
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, 3 BY BUILDING REGULATORY AUTHORITY AND RISK CATEGORY Col2 Col3 Col4 BUILDING REGULATORY AUTHORITY RISK CATEGORY PERFORMANCE CRITERIA1 PERFORMANCE CRITERIA1 BUILDING REGULATORY AUTHORITY RISK CATEGORY Level 1 Level 2 State-Owned [BSC] I, II, III BSE-R, S-3, N-C BSE-C, S-5, N-D State-Owned [BSC] IV BSE-R, S-1, N-B BSE-C, S-3, N-D Division of the State Architect - [DSA-SS] I BSE-1N, S-3, N-B BSE-2N, S-5, N-D Division of the State Architect - [DSA-SS] II, III BSE-1N, S-2, N-B BSE-2N, S-4, N-D Division of the State Architect - [DSA-SS] 4 IV BSE-1N, S-1, N-A BSE-2N, S-3, N-D Division of the State Architect - [DSA-SS/CC] I, II BSE-1E, S-3, N-C BSE-2N, S-5, N-D Division of the State Architect - [DSA-SS/CC] III BSE-1E, S-3, N-B BSE-2N, S-5, N-D Division of the State Architect - [DSA-SS/CC] IV BSE-1E, S-1, N-B BSE-2N, S-3, N-D _1. 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,
California Existing Building Code High relevance — show source text
|100 psf|1 hr
23 min|||7|1, 2|11/3| |F/C-4-RC-9|4″|4″ deep (4370 psi);1/4″ reinforcement bars
at 6″ pitch with3/4″ cover;1/4″ main rein-
forcement bars at 4″ pitch perpendicular
with1/2″ cover; 13′1″ span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-10|4″|4″ thick (5140 psi) deck;1/4″ reinforce-
ment bars at 71/2″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|1 hr
16 min|||7|1, 5|11/4| |F/C-4-RC-11|4″|4″ thick (4000 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom of slab; 6′6″
span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-12|4″|4″ deep (2380 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom surface;
6′6″ span restrained.|150 psf|1 hr
3 min|||7|1, 2|1| |F/C-4-RC-13|41/2″|41/2″ thick (5200 psi) deck;1/4″ reinforce-
ment bars at 71/4″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-14|41/2″|41/2″ deep (2525 psi) concrete deck;1/4″
reinforcement bars at 71/2″ pitch with7/8″
cover;3/8″ main reinforcement bars at
33/8″ pitch perpendicular with1/2″ cover;
13′1″ span restrained.|150 psf|42 min|||7|1, 5|2/3| |F/C-4-RC-15|41/2″|41/2″ deep (4830 psi) concrete deck;
11/2″ × No.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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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 § 3-20 High relevance — show source text
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319.12.2 Public schools and community colleges. [DSA-SS, DSA-SS/CC] When Section 319.12 is the basis for structural modifications, the approved design documents must clearly indicate the scope of modifications and the acceptance criteria for the design.
SECTION 320 [BSC, DSA-SS & DSA-SS/CC]—METHOD A
320.1 General. The retrofit design shall employ the Linear Static or Linear Dynamic Procedures of ASCE 41, Section 7.4.1 or 7.4.2, and comply with the applicable general requirements of ASCE 41, Chapters 6 and 7. The earthquake hazard level and performance level given specified in Section 317.5 for the building’s risk category shall be used. Structures shall be designed for seismic forces coming from any horizontal direction.
SECTION 321 [BSC, DSA-SS & DSA-SS/CC]—METHOD B
321.1 The existing or retrofitted structure shall be demonstrated to have the capability to sustain the deformation response due to the specified earthquake ground motions and meet the seismic performance requirements of Section 317. The registered design professional shall provide an evaluation of the response of the existing structure in its modified configuration and condition to the ground motions specified. If the building’s seismic performance is evaluated as satisfactory and the peer reviewer(s) and the enforcement agency concurs, then no further structural retrofit and/or repair of the lateral load-resisting system is required.
When the evaluation indicates the building does not meet the required performance levels given in Table 317.5 for the risk category, then a retrofit and/or repair design shall be prepared that provides a structure that meets these performance objectives and reflects the appropriate consideration of existing conditions. Any approach to analysis and design is permitted to be used, provided that the approach shall be rational, shall be consistent with the established principals of mechanics and shall use the known performance characteristics of materials and assemblages under reversing loads typical of severe earthquake ground motions.
Exception: Further consideration of the structure’s seismic performance may be waived by the enforcement agency if both the registered design professional and peer reviewer(s) conclude that the structural system can be expected to perform at least as well as required by the provisions of this section without completing an analysis of the structure’s compliance with these requirements. A detailed report shall be submitted to the responsible building official that presents the reasons and basis for this conclusion. This report shall be prepared by the registered design professional. The peer reviewer(s) shall concur in this conclusion and affirm to it in writing. The building official shall either approve this decision or require completion of the indicated work specified in this section prior to approval.
321.2 The approach, models, analysis procedures, assumptions on material and system behavior and conclusions shall be peer reviewed in accordance with the requirements of Section 322 and accepted by the peer reviewer(s).
Exceptions: 1. The enforcement agency may perform the work of peer review when qualified staff is available within the jurisdiction. 2. The enforcement agency may modify or waive the requirements for peer review when appropriate.
CEBC § 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:
- The forces need not exceed 0.75 times the seismic forces prescribed by the regular code requirements.
- For Risk Category I, II or III structures, near-fault increases in ground motion (maximum considered earthquake ground motion of 0.2 second spectral response greater than 150 percent at 5 percent damping) need not be considered when the fundamental period of the building is 0.5 seconds in the direction under consideration.
- For Risk Category I or II structures, the seismic base shear need not exceed 0.30W.
- For Risk Category III or IV structures, the seismic base shear need not exceed 0.40W.
8-706.1.1 When a building is to be strengthened with the addition of a new lateral force resisting system, the R -value of the new system can be used when the new lateral force resisting system resists at least 75 percent of the building’s base shear regardless of its relative rigidity.
8-706.1.2 Evaluation and seismic improvement of unreinforced masonry bearing wall buildings shall comply with the California Existing Building Code (CEBC), Appendix Chapter A1 2013 Edition, and as modified by the CHBC.
Exceptions:
- Alternative standards may be used on a case-by-case basis when approved by the authority having jurisdiction. It shall be permitted to exceed the strength limitation of 100 psi in Section A108.2 of the CEBC when test data and building configuration supports higher values subject to the approval of the authority having jurisdiction.
- CEBC Section A102.2 shall not apply to Qualified Historical Buildings in Risk Category III buildings and other structures whose primary occupancies are public assembly with an occupancy load greater than 300.
8-706.1.3 All deviations from the detailing provisions of the lateral-force-resisting systems shall be evaluated for stability and the ability to maintain load-carrying capacity at the expected inelastic deformations.
8-706.2 Existing building performance. The seismic resistance may be based upon the ultimate capacity of the structure to perform, giving due consideration to ductility and reserve strength of the lateral-force-resisting system and materials while maintaining a reasonable factor of safety. Broad judgment may be exercised regarding the strength and performance of materials not recognized by regular code requirements. (See Chapter 8-8, Archaic Materials and Methods of Construction.)
8-706.2.1 All structural materials or members that do not comply with detailing and proportioning requirements of the regular code shall be evaluated for potential seismic performance and the consequence of non-compliance. All members that would be reasonably expected to fail and lead to collapse or life threatening injury when subjected to seismic demands shall be judged unacceptable, and appropriate structural strengthening shall be developed.
8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.
CEBC § 319.9 High relevance — show source text
Exception: A component’s strength is permitted to be less than that required by the specified seismic load combinations if it can be demonstrated that the associated reduction in seismic performance of the component or its removal due to the failure does not result in a structural system that does not comply with the required performance objectives of Section 317. If this exception is taken for a component, then it cannot be considered part of the primary lateral-load-resisting system.
319.9 Nonstructural component requirements. Where the nonstructural performance levels required by Section 317, Table 317.5 are N-D or higher, mechanical, electrical and plumbing components shall comply with the provisions of ASCE 41, Chapter 13, Section 13.2.
Exception: Modifications to the procedures and criteria may be made subject to approval by the building official, and concurrence of the peer reviewer if applicable. All reports and correspondence shall also be forwarded to the building official.
319.10 Structural observation, testing and inspection. Structural observation, testing and inspection as used in this section shall mean meeting the requirements of Chapter 17 of the California Building Code, with a minimum allowable level of investigation corresponding to seismic design category (SDC) D. Structural observation visits shall occur at significant construction stages and at the completion of the structural retrofit. Structural observation shall be provided for all structures.
Additional requirements: [DSA-SS, DSA-SS/CC] For public schools and community colleges, construction material testing, inspection and observation during construction shall also comply with the California Administrative Code.
319.10.1 The requirement for structural observation shall be noted and prominently displayed on the front sheet of the approved plans and incorporated into the general notes on the approved plans.
319.10.2 Preconstruction meeting. A preconstruction meeting is mandatory for all projects which require structural observation. The meeting shall include, but is not limited to, the registered design professional, structural observer, general constructor, affected subcontractors, the project inspector and a representative of the enforcement agency (designated alternates may attend if approved by the structural observer). The structural observer shall schedule and coordinate this meeting. The purpose of the meeting is to identify and clarify all essential structural components and connections that affect the lateral and vertical load systems and to review scheduling of the required observations for the project’s structural system retrofit.
319.11 Temporary actions. When compatible with the building use, and the time phasing for both use and the retrofit program, temporary shoring or other structural support is permitted to be considered. Temporary bracing, shoring and prevention of falling hazards are permitted to be used to qualify for Item 1 in Section 319.12 that allows inadequate capability in some existing components, as long as the required performance levels given in Section 317 can be provided by the permanent structure. The consideration for such temporary actions shall be noted in the design documents.
319.12 Voluntary modifications to the lateral-force resisting system. Where modifications of existing structural components and additions of new structural components are initiated for the purpose of improving the lateral-force resisting strength or stiffness of an existing structure and they are not required by other sections of this code, then they are permitted to be designed to meet an approved seismic performance criteria provided that an engineering analysis is submitted that follows: 1. The capacity of existing structural components required to resist forces is not reduced, unless it can be demonstrated that
CEBC § 319.7.1 High relevance — show source text
319.7.1 A building with prestressed or post- tensioned structural components (beams, columns, walls or slabs) or precast structural components (beams, columns, walls or flooring systems).
319.7.2 A building classified as irregular per Section 319.5.
Exceptions: 1. The retrofit design removes the configurational attributes that caused the building to be classified as irregular. 2. The irregularity is demonstrated not to affect the seismic performance of the building.
319.7.3 A building assigned to Risk Category IV per Section 319.4.
319.7.4 A building with an undefined or hybrid structural system.
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319.7.5 A building with a seismic isolation or energy dissipation system, either as part of the existing structure or as part of the retrofit.
319.7.6 A building greater than 240 feet (73 m) in height.
319.7.7 A building evaluated per ASCE 41 and its application requires the use of a nonlinear analysis procedure.
319.8 Strength requirements. All components of the lateral-force-resisting system must have the strength to meet the acceptance criteria prescribed in ASCE 41, Chapter 7 or as prescribed in the applicable Appendix A chapter of this code if a specific procedure in Section 319.1.1 is used. Any component not having this strength shall have its capacity increased by modifying or supplementing its strength so that it exceeds the demand, or the demand is reduced to less than the existing strength by making other modifications to the structural system.
Exception: A component’s strength is permitted to be less than that required by the specified seismic load combinations if it can be demonstrated that the associated reduction in seismic performance of the component or its removal due to the failure does not result in a structural system that does not comply with the required performance objectives of Section 317. If this exception is taken for a component, then it cannot be considered part of the primary lateral-load-resisting system.
319.9 Nonstructural component requirements. Where the nonstructural performance levels required by Section 317, Table 317.5 are N-D or higher, mechanical, electrical and plumbing components shall comply with the provisions of ASCE 41, Chapter 13, Section 13.2.
Exception: Modifications to the procedures and criteria may be made subject to approval by the building official, and concurrence of the peer reviewer if applicable. All reports and correspondence shall also be forwarded to the building official.
319.10 Structural observation, testing and inspection. Structural observation, testing and inspection as used in this section shall mean meeting the requirements of Chapter 17 of the California Building Code, with a minimum allowable level of investigation corresponding to seismic design category (SDC) D. Structural observation visits shall occur at significant construction stages and at the completion of the structural retrofit. Structural observation shall be provided for all structures.
Additional requirements: [DSA-SS, DSA-SS/CC] For public schools and community colleges, construction material testing, inspection and observation during construction shall also comply with the California Administrative Code.
CEBC § 317.1.2.1 Medium 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 § 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.
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317.10 Where Method B of Section 321 is used or is required by Section 319.7, the proposed method of building evaluation and design procedures must be accepted by the building official prior to the commencement of the work.
317.11 Voluntary lateral-force-resisting system modifications. Where the exception of Section 317.2 applies, modifications of existing structural components and additions of new structural components that are initiated for the purpose of improving the seismic performance of an existing structure and that are not required by other portions of this chapter are permitted under the requirements of Section 319.12.
SECTION 318 [BSC, DSA-SS & DSA-SS/CC]—DEFINITIONS
318.1 In addition to the definitions given in Section 202, for the purposes of Sections 317 through 323, certain terms are defined as follows:
[DSA-SS & DSA-SS/CC] For the purposes of Section 317 through 323, definitions of terms given in Section 4-207 or 4-314 of the California Administrative Code govern over those in Section 202.
ADDITION [BSC] means any work that increases the floor or roof area or the volume of enclosed space of an existing building, and is structurally attached to the existing building by connections that are required for transmitting vertical or horizontal loads between the addition and the existing structure.
CEBC § 501A.3 Medium relevance — show source text
501 A .2 Fire-resistance ratings. Fire-resistance ratings shall comply with the California Building Standards Code.
501A.3 Prescriptive compliance provisions. Alterations, additions and changes of occupancy to the following categories of existing buildings and structures shall comply with the provisions of this section.
501A.3.1 Prescriptive compliance provisions for SPC-4D using the California Building Code, 1980 (CBC 1980). Nonconforming buildings shall satisfy the following requirements: 1. The California Building Code, 1980 (CBC 1980), as used in this chapter, consists of the Uniform Building Code, 1979 (UBC 1979) along with requirements contained in: a) California Code of Regulations, Title 24- Building Standards, dated February 2, 1980 (Revision record for Register 80, No. 5). b) California Code of Regulations, Title 22 – Social Security, dated October 13, 1979 (Revision Record for Register 79, No 41). c) California Code of Regulations, Title 17 – Public Health, dated October 13, 1979 (Revision Record for Register 79, No 41-B). 2. All existing structural elements of Seismic Force Resisting System (SFRS) shall satisfy the detailing requirements in the CBC 1980 or demonstrate that the level of seismic performance is equivalent to that given in the CBC 1980, as determined by the building official. 3. A continuous load path or paths with adequate strength and stiffness to transfer all the forces from the point of origin to final point of resistance shall be justified by analysis. 4. Site data report in accordance with the CBC 1980 shall establish that seismically induced differential settlement does not exceed 1 ″ in 40 ′ .
5. Adjacent buildings shall satisfy the SPC building separation requirements in accordance with the California Administrative Code, Chapter 6 Section 3.4. 6. The addition of new structural elements or strengthening of existing structural elements for retrofit of nonconforming build- ings to SPC-4D shall comply with the following: a) The seismic demand (forces or displacements) shall be in accordance with the CBC 1980; b) Capacity, detailing and connections for new structural elements shall satisfy the requirements in the CBC 2025 for new construction; and c) The strengthening of existing structural elements shall use capacities determined in accordance with the CBC 2025 for new construction consistent with the detailing and connections used in the strengthened member. 7. All construction, quality assurance and quality control shall be in accordance with the new construction provisions of CBC 2025.
8. Elements not part of the Seismic Force-Resisting System (SFRS), including those identified in the California Administrative Code Chapter 6, Article 10, shall be evaluated using seismic forces and the requirements of the CBC 1980. 9. Any column or wall that forms part of two or more intersecting SFRS and is subjected to axial load due to seismic forces acting along either principal plan axis equaling or exceeding 20 percent of the axial design strength of the column or wall shall be _evaluated for the most critical load effect due to application of seismic force in any direction.
CEBC § 319.8. Medium relevance — show source text
unless it can be demonstrated that_ reduced capacity meets the requirements of Section 319.8. 2. The lateral loading to or strength requirement of existing structural components is not increased beyond their capacity. 3. New structural components are detailed and connected to the existing structural components as required by the California Building Code. 4. New or relocated nonstructural components are detailed and connected to existing or new structural components as required by the California Building Code. 5. A dangerous condition is not created.
Use of ASCE 41 Tier 1 and Tier 2 deficiency only retrofit procedures are pre-approved for use where Section 317.3 does not require an
assessment.
319.12.1 State-owned buildings. [BSC] Voluntary modifications to lateral force-resisting systems conducted in accordance with Appendix A of this code and the referenced standards of the California Building Code shall be permitted.
319.12.1.1 Design documents. [BSC] When Section 319.12 is the basis for structural modifications, the approved design documents must clearly state the scope of the seismic modifications and the accepted criteria for the design. The approved design documents must clearly have the phrase “The seismic requirements of the California Existing Building Code have not been checked to determine if these structural modifications meet the full seismic evaluation and strengthening requirements of Sections 317-322: the modifications proposed are to a different seismic performance standard than would be required in Section 319 if they were not voluntary as allowed in Section 319.12.”
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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.
Frequently asked questions
What is the single document I must follow to find the minimum seismic targets?
Follow § 317.5 and Table 317.5 in the CEBC — they list the Seismic Hazard Level, structural S‑level and nonstructural N‑level required for each regulatory authority and Risk Category.
Do I need to run two separate analyses for Level 1 and Level 2?
Yes — § 317.5 requires evaluation to both Level 1 and Level 2 using a Tier 3 ASCE 41 procedure; the more restrictive outcome controls.
When does the large‑addition exception change the hazard level?
If the addition’s floor area > 50% of the original floor area or > 1,000 sq ft, the table entries of BSE‑R/BSE‑1E and BSE‑C are replaced by BSE‑1N and BSE‑2N, respectively (see § 317.5).
If Table 317.5 requires N‑D for nonstructural items, what standard applies?
When Table 317.5 requires N‑D or higher, mechanical, electrical and plumbing components must comply with ASCE 41 Chapter 13, Section 13.2, per § 319.9.
If my building meets the Level 1 target but not Level 2, must I retrofit?
Yes — you must evaluate both Level 1 and Level 2 and retrofit to meet the more restrictive of the two per § 317.5; if the more restrictive level is not met, retrofit is required (see § 317.6). file
More in California Existing Building Code
- Administration and Definitions (Scope, enforcement, code official duties, definitions)
- Provisions for All Compliance Methods (general requirements that apply to all compliance options; Chapter 3 / 3A)
- Seismic retrofit and evaluation (Appendix A and seismic provisions/sections for evaluation and retrofit)
- Referenced Standards and Appendices (Chapter 16 and Appendices A–E, Resource A)
- Repairs (Chapter 4 — repair-specific rules for materials, means of egress, structural, MEP, etc.)
- Alterations — Level 1, Level 2, Level 3 (technical requirements for each alteration level; Chapters 7–9)
- Change of Occupancy and Additions (requirements for occupancy changes and additions; Chapters 10–11)
- Compliance Methods — Prescriptive, Work Area, Performance (Chapters 5, 6–11, 13)
- Relocated Buildings (requirements for buildings moved or relocated; Chapter 14)
- Construction Safeguards (site safety, means of egress and life-safety during construction; Chapter 15)
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