CEBC · California Existing Building Code
What evaluation and retrofit are required after substantial structural earthquake damage?
If an earthquake causes **substantial structural damage** (e.g., >33% loss of lateral capacity in a story), the CEBC requires a licensed engineer or architect to evaluate whether the building, if repaired to predamage condition, would meet California Building Code wind/earthquake and CEBC §304.3.2 criteria. If it would, you may restore the damaged parts; if not, you must retrofit the lateral system and foundation to CEBC standards, using seismic loads at least equal to the original code level and no less than **75%** of CBC §1613A.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
If a building has sustained substantial structural damage to the vertical elements of its lateral force‑resisting system, the building must be evaluated by a registered design professional and either be repaired to predamage condition (if the evaluation shows the predamage system is compliant) or be repaired and retrofitted to meet the code retrofit requirements. This mandatory evaluation and the two possible outcomes are set out in § 405.2.3 and its subparts § 405.2.3.1 and § 405.2.3.3 of the California Existing Building Code (CEBC) .
If vertical lateral elements lost more than 33% of their lateral capacity (or other defined thresholds), have the building evaluated by a licensed engineer — restore to predamage condition only if the evaluation shows the predamage system complies with the California Building Code; otherwise plan a seismic retrofit to the CEBC retrofit requirements.
Requirements in detail
Key defined terms (first mention bolded)
- Substantial structural damage — a CEBC definition that includes, for example, a condition where the vertical elements of the lateral force‑resisting system have lost more than 33 percent of the lateral load capacity of any story in any horizontal direction (among other criteria). See the CEBC definitions for full criteria.
- Registered design professional — the licensed engineer or architect required to perform the evaluation and submit findings to the code official (CEBC requires the evaluation be performed and submitted by such a professional).
- Lateral force‑resisting system and foundation — the system that resists wind and seismic lateral loads and its supporting foundation; both must be considered in the evaluation and, if required, retrofitted.
What the evaluation must determine (§ 405.2.3.1)
The building must be evaluated by a registered design professional, and the evaluation findings must be submitted to the building official. § 405.2.3.1 requires the evaluation to establish whether the lateral force‑resisting system, including its foundation, if restored to its predamage state, would comply with:
- The California Building Code for load combinations that include wind and earthquake effects, and
- CEBC Section 304.3.2 (the CEBC seismic evaluation/retrofit criteria referenced by the repairs chapter).
For earthquake loads used in that evaluation the CEBC allows adjustments (see the table below and § 405.2.3.1 for specific provisions and permissible reductions where applicable).
Repair vs. retrofit decision (§ 405.2.3.2 and § 405.2.3.3)
- If the evaluation concludes the predamage lateral system does comply with the applicable CBC/CEBC provisions, the damaged elements may be restored to their predamage condition (repair only). § 405.2.3.2
- If the evaluation concludes the predamage lateral system does not comply, then the lateral force‑resisting system and its foundation shall be retrofitted to comply with the CEBC requirements. § 405.2.3.3 requires:
- Retrofit to meet the CEBC criteria (including Section 304.3.2).
- Wind loads for retrofit are the code wind loads in effect at time of original construction (unless damage was caused by wind, in which case current CBC wind loads apply).
- Earthquake loads used for retrofit shall not be less than those required by the building code in effect at the time of original construction, and in no case shall they be less than 75 percent of the earthquake loads prescribed in California Building Code Section 1613A (CEBC explicitly sets this lower bound) — see § 405.2.3.3 for the authority to use alternate ASCE‑41 based procedures for certain SPC classifications.
Decision‑relevant dimensions — quick reference table
| Decision factor / threshold | What it means for the owner/designer | Code reference |
|---|---|---|
| Loss of > 33% lateral capacity (vertical elements) | Triggers substantial structural damage classification and requires evaluation. | § 405.2.3; CEBC Definitions |
| Loss > 20% gravity capacity for elements with >30% tributary area & remaining <75% of CBC requirements | Also counts as substantial structural damage for gravity elements; leads to retrofit obligations (see § 405.2.4). | CEBC Definitions; § 405.2.4 |
| Who evaluates? | Must be a registered design professional; findings submitted to building official. | § 405.2.3.1 |
| Evaluation objective | Establish whether predamage lateral system (if repaired) would comply with CBC load combinations including wind & earthquake and CEBC § 304.3.2. | § 405.2.3.1 |
| If evaluation = compliant | Damaged elements may be restored to predamage condition (repair only). | § 405.2.3.2 |
| If evaluation = noncompliant | Retrofit lateral system + foundation to comply with CEBC (304.3.2). Earthquake loads ≥ original construction code level but not < 75% of CBC §1613A. | § 405.2.3.3 |
| Alternate evaluation/retrofit options | For certain SPC classifications, CEBC permits using Section 304A.3.4.x rehabilitation options or ASCE‑41 procedures as noted in § 405.2.3.3. | § 405.2.3.3 and Section 304A.3.4.* |
How retrofit loads are set
- Wind: use the code wind loads in effect at the time of original construction (unless damage was caused by wind; then use current CBC wind loads). § 405.2.3.3
- Seismic: retrofit earthquake loads shall be at least the historic code level (code in effect at original construction) and not less than 75% of the CBC Section 1613A seismic loads; CEBC also permits specific alternative rehabilitation procedures for certain SPC categories (see § 405.2.3.3).
Exceptions & special cases
- Buildings assigned 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 (exception in § 405.2.3).
- One‑ and two‑family dwellings are not required to be evaluated or retrofitted for load combinations that include earthquake effects under these CEBC sections (exception in § 405.2.3).
- If gravity load‑carrying components sustained substantial structural damage, they must be retrofitted to meet CBC dead/live/snow load provisions; if those gravity failures were caused primarily by seismic or wind effects, the building must be evaluated per § 405.2.3.1 and, if noncompliant, retrofitted under § 405.2.3.3. See § 405.2.4 and § 405.2.4.1 for the linkage between gravity damage and lateral system evaluation.
Common mistakes
- Assuming a visual inspection by a non‑engineer is sufficient — the CEBC requires a registered design professional for the evaluation (§ 405.2.3.1) .
- Treating every crack or partial member damage as “substantial” without quantifying capacity loss — the CEBC uses numeric thresholds (e.g., 33%) to define substantial structural damage; apply the definition before triggering retrofit requirements.
- Using current seismic loads arbitrarily for retrofits when the code requires using the loads in effect at original construction (unless one of the permitted alternatives applies) — § 405.2.3.3 prescribes the correct lower bound (not less than 75% of CBC §1613A) and rules for wind/seismic selection.
- Forgetting to evaluate foundations — CEBC explicitly requires the evaluation to include the foundation if it will be returned to predamage condition. § 405.2.3.1
- Overlooking related CEBC sections (e.g., § 304.3.2, § 405.2.4) when gravity elements are damaged — those cross‑references change what must be evaluated and retrofitted.
Worked example — applying the rule with numbers
Scenario: A 4‑story commercial building in SDC D experiences an earthquake. A structural assessment shows the first story lateral capacity (in one horizontal direction) is reduced from a predamage base shear capacity of 200 kips to 120 kips.
Step 1 — Determine percent loss:
- Percent loss = (200 − 120) / 200 = 40% loss of lateral capacity for that story direction. This exceeds 33%, so the condition meets the CEBC definition of substantial structural damage and triggers the evaluation requirement under § 405.2.3.
Step 2 — Perform required evaluation:
- A registered design professional must evaluate whether the lateral force‑resisting system (including foundation), if repaired to predamage condition, would comply with the California Building Code load combinations (wind + earthquake) and CEBC § 304.3.2 per § 405.2.3.1. If the evaluator finds the predamage system would comply, the owner may restore the damaged elements to their predamage condition per § 405.2.3.2.
Step 3 — If evaluation finds noncompliance:
- The CEBC requires the lateral system and foundation to be retrofitted to comply with CEBC requirements. The design must use seismic loads not less than the loads required by the building code in effect at original construction, and not less than 75% of CBC §1613A. Practically, the design team will calculate target retrofit forces per the allowed seismic level (historic code level or the 75% CBC §1613A minimum), produce retrofit plans, and obtain code official approval. § 405.2.3.3 governs these steps.
Related provisions (CEBC sections)
- § 405.2.3 — Substantial structural damage to vertical elements; evaluation and repair/retrofit decision.
- § 405.2.3.1 — Evaluation required; registered design professional; scope (lateral system + foundation; wind & earthquake loads; reference to § 304.3.2).
- § 405.2.3.2 — Extent of repair for compliant buildings (restore to predamage condition).
- § 405.2.3.3 — Extent of repair for noncompliant buildings; retrofit requirements; wind and earthquake load rules including the 75% CBC §1613A floor.
- § 405.2.4 and § 405.2.4.1 — Substantial structural damage to gravity load‑carrying components and linkage to lateral system evaluation/retrofit (when gravity damage is wind/seismic‑caused).
- § 304.3.2 — Seismic evaluation/retrofit criteria referenced by § 405.2.3.1 and § 405.2.3.3 (see CEBC Chapter 3A/4A for details).
- Section references on alternate rehabilitation procedures and SPC classifications: Section 304A.3.4.4 – 304A.3.4.6 (where CEBC identifies allowable alternative seismic evaluation/rehabilitation methods for certain SPC buildings).
(If you need, I can extract the exact CEBC paragraphs for § 405.2.3, § 405.2.3.1 and § 405.2.3.3 as printed language and provide them as a compliance checklist — the article above summarizes and interprets those sections grounded in the CEBC wording.)
Code references
Grounded in the retrieved California Existing Building Code — click a citation to read the verbatim passage:
CEBC § 405.2.3.1 High relevance — show source text
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- 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.
[BS] 405.2.4 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.
[BS] 405.2.4.1 Lateral force-resisting elements. Regardless of the level of damage to vertical elements of the lateral forceresisting 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 405.2.3.1 and, if noncompliant, retrofitted in accordance with Section 405.2.3.3.
Exceptions:
- 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.
- One- and two-family dwellings need not be evaluated or retrofitted for load combinations that include earthquake effects.
[BS] 405.2.5 Substantial structural damage to snow load-carrying components. Where substantial structural damage to any snow load-carrying components is caused by or related to snow load effects, any components required to carry snow loads on roof framing of similar construction shall be repaired, replaced or retrofitted to satisfy the requirements of Section 1608 of the California Building Code .
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 § 2.2 High relevance — show source text
405 A .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.
405 A .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 A .2.3.1, and either repaired in accordance with Section 405 A .2.3.2 or repaired and retrofitted in accordance with Section 405 A .2.3.3, depending on the results of the evaluation.
405 A .2.3.1 Evaluation. The building shall be evaluated by a registered design professional, and the evaluation findings shall be submitted to the building 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 and earthquake effects. Earthquake loads for this evaluation, if required, shall
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be permitted to be 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 earthquake load evaluation shall be permitted to be performed in accordance with Section 304A.3.4.4 for SPC-2 buildings and Section 304A.3.4.5 for buildings rated SPC-3, SPC-4D and SPC-4. SPC-5 buildings shall be permitted to be evaluated in accordance with Section 304A.3.4.6, except that the seismic hazard shall be permitted to be reduced to BSE-1E and BSE-2E.
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.
CEBC § 405.2.4 High relevance — show source text
[BS] 405.2.4 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.
[BS] 405.2.4.1 Lateral force-resisting elements. Regardless of the level of damage to vertical elements of the lateral forceresisting 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 405.2.3.1 and, if noncompliant, retrofitted in accordance with Section 405.2.3.3.
Exceptions:
- 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.
- One- and two-family dwellings need not be evaluated or retrofitted for load combinations that include earthquake effects.
[BS] 405.2.5 Substantial structural damage to snow load-carrying components. Where substantial structural damage to any snow load-carrying components is caused by or related to snow load effects, any components required to carry snow loads on roof framing of similar construction shall be repaired, replaced or retrofitted to satisfy the requirements of Section 1608 of the California Building Code .
[BS] 405.2.6 Flood hazard areas. In flood hazard areas, buildings that have sustained substantial damage shall be brought into compliance with Section 1612 of the California Building Code or Section R306 of the California Residential Code, as applicable.
SECTION 406—ELECTRICAL
[OSHPD 1R, 2, 4 & 5] Not adopted by OSHPD. Existing electrical wiring and equipment undergoing repair shall be in accordance with Title 24 Part 3 California Electrical Code (CEC).
406.1 General. Repairs to existing electrical wiring and equipment shall be in accordance with the California Electrical Code.
406.1.1 Reconditioned electrical equipment. Reconditioned electrical equipment shall comply with the California Electrical Code . Electrical equipment prohibited from being reconditioned by the applicable sections of the California Electrical Code shall not be reconditioned unless permitted by NFPA 99.
406.1.2 Health care facilities. Portions of electrical systems being repaired in Group I-2, ambulatory care facilities and outpatient clinics shall comply with NFPA 99 requirements for repairs.
SECTION 407—MECHANICAL
407.1 General. Existing mechanical systems undergoing repair shall not make the building less complying than it was before the damaged occurred. [HCD 1, HCD 2 & BSC] Existing mechanical systems undergoing repair shall comply with the California Mechanical Code.
SECTION 408—PLUMBING
408.1 Materials. Plumbing materials and supplies shall not be used for repairs that are prohibited in the California Plumbing Code .
CEBC § 2.3.2 High relevance — show source text
405 A .2.3.2 Extent of repair for compliant buildings. If the evaluation establishes that the building in its predamage condition complies with the provisions of Section 405.2.3.1, then the damaged elements shall be permitted to be restored to their predamage condition.
405 A .2.3.3 Extent of repair for noncompliant buildings. If the evaluation does not establish that the lateral force-resisting system of the building in its predamage condition complies with the provisions of Section 405.2.3.1, then the lateral forceresisting system, and its foundation, shall be retrofitted to comply with the provisions of this section. The wind loads for the repair and retrofit shall be those required by the building code in effect at the time of original construction, unless the damage was caused by wind, in which case the wind loads shall be in accordance with the California Building Code . The earthquake loads shall not be less than those required by the building code in effect at the time of original construction but not less than 75 percent of those prescribed in California Building Code Section 1613A. Alternatively, where the earthquake damage has not resulted in disproportionate earthquake damage or did not result in collapse, the retrofit shall be permitted to be performed in accordance with Section 304A.3.4.4 for SPC-2 buildings, Section 304A.3.4.5 for SPC-3, SPC-4D and SPC-4 buildings and Section 304A.3.4.6 for SPC-5 buildings. For SPC-5 buildings, the seismic hazard shall be permitted to be reduced to BSE-1E and BSE-2E. Use of Section 304A.3.4.5 to rehabilitate SPC-3, SPC-4D and SPC-4 buildings will result in re-classification of the building to SPC-4D. Noncompliant SPC-4 buildings may be rehabilitated to SPC-5 in accordance with Section 304A.3.4.6 using the reduced seismic hazard. New structural members and connections required by this rehabilitation design shall comply with the detailing provisions of this code for new buildings of similar structure, purpose and location.
405 A .2.4 Substantial structural damage to gravity load-carrying components. Gravity load-carrying components that have sustained substantial structural damage shall be retrofitted to comply with the applicable provisions for dead, live and snow loads in the California Building Code . Undamaged gravity load-carrying components, including undamaged foundation components, that receive dead, live or snow loads from retrofitted components shall also be retrofitted if required to comply with these design loads. New structural members and connections required by this rehabilitation design shall comply with the detailing provi- sions of this code for new buildings of similar structure, purpose and location.
405 A .2.4.1 Lateral force-resisting elements. Regardless of the level of damage to vertical elements of the lateral force-resisting system, if substantial structural damage to gravity load-carrying components was caused primarily by wind or seismic effects, then the building shall be evaluated in accordance with Section 405 A .2.3.1 and, if noncompliant, retrofitted in accordance with Section 405 A .2.3.3.
Exceptions:
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 § 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:
- 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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- 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 § 503.7 High relevance — show source text
[BS] 503.7 Anchorage for concrete and reinforced masonry walls. Where the work area exceeds 50 percent of the building area, the building is assigned to Seismic Design Category C, D, E or F and the building’s structural system includes concrete or reinforced masonry walls with a flexible roof diaphragm, 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] 503.8 Anchorage for unreinforced masonry walls in major alterations. Where the work area exceeds 50 percent of the building area, the building is assigned to Seismic Design Category C, D, E or F and the building’s structural system 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 floor and roof lines.
[BS] 503.9 Bracing for unreinforced masonry parapets in major alterations. Where the work area exceeds 50 percent of the building area, and where the building is assigned to Seismic Design Category C, D, E or F, and the building has parapets constructed of unreinforced masonry, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of parapet bracing to resist out-of-plane seismic forces.
[BS] 503.10 Anchorage of unreinforced masonry partitions in major alterations. Where the work area exceeds 50 percent of the building area, or where the building is assigned to Seismic Design Category C, D, E or F, and the building has unreinforced masonry partitions and nonstructural walls, the alteration work shall include evaluation of the existing condition or removal, anchoring or alteration of any such partitions or walls within the work area and adjacent to egress paths from the work area, to comply with Section 304.3.2.
[BS] 503.11 Substantial structural alteration. Where the work area exceeds 50 percent of the building area and where work involves a substantial structural alteration, the lateral load-resisting system of the altered building shall 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:
- 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 .
- Where the intended alteration involves structural components of the lowest story of a building, only the lateral loadresisting system above that story need not comply with this section.
[BS] 503.12 Roof diaphragms resisting wind loads in high-wind regions. Where the intended alteration requires a permit for reroofing and involves removal of roofing materials from more than 50 percent of the roof diaphragm of a building or section of a building located where the basic wind speed, V, is greater than 130 mph (58 m/s) in accordance with Figure 1609.3(2) of the California
CEBC § 3.4. High relevance — show source text
[BS] ROOF COATING. A fluid-applied adhered coating used for roof maintenance, roof repair or as a component of a roof covering system or roof assembly.
[BS] ROOF RECOVER. The process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof covering.
[BS] ROOF REPAIR. Reconstruction or renewal of any part of an existing roof for the purpose of correcting damage or restoring the predamage condition.
[BS] ROOF REPLACEMENT. The process of removing the existing roof covering, repairing any damaged substrate and installing a new roof covering.
SPC SEISMIC SEPARATION. [OSHPD 1 & 1R] Means a building separation in accordance with the California Administrative Code, Chap- ter 6 Section 3.4.
SUBSTANDARD BUILDING. [HCD 1, HCD 2] See Health and Safety Code Section 17920.3.
[BG] STORM SHELTER. A building, structure or portions thereof, constructed in accordance with ICC 500, designated for use during hurricanes, tornadoes or other severe windstorms.
[BS] SUBSTANTIAL DAMAGE. For the purpose of determining compliance with the flood provisions of this code, damage of any origin sustained by a structure whereby the cost of restoring the structure to its before-damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.
[BS] SUBSTANTIAL IMPROVEMENT. For the purpose of determining compliance with the flood provisions of this code, any repair, alteration, addition or improvement of a building or structure, the cost of which equals or exceeds 50 percent of the market value of the structure, before the improvement or repair is started. If the structure has sustained substantial damage, any repairs are considered substantial improvement regardless of the actual repair work performed. The term does not, however, include either of the following:
- Any project for improvement of a building required to correct existing health, sanitary or safety code violations identified by the code official and that is the minimum necessary to ensure safe living conditions.
- Any alteration of a historic structure, provided that the alteration will not preclude the structure’s continued designation as a historic structure.
[BS] SUBSTANTIAL STRUCTURAL ALTERATION. An alteration in which the gravity load-carrying structural elements altered within a 5-year period support more than 30 percent of the total floor and roof area of the building or structure. The areas to be counted toward the 30 percent shall include mezzanines, penthouses, and in-filled courts and shafts tributary to the altered structural elements.
[BS] SUBSTANTIAL STRUCTURAL DAMAGE. A condition where any of the following apply:
- The vertical elements of the lateral force-resisting system have suffered damage such that the lateral load-carrying capacity of any story in any horizontal direction has been reduced by more than 33 percent from its predamage condition.
- The capacity of any vertical component carrying gravity load, or any group of such components, that has a tributary area more than 30 percent of the total area of the structure’s floor(s) and roof(s) has been reduced more than 20 percent from its predamage condition, and the remaining capacity of such affected elements, with respect to all dead and live loads, is less than 75 percent of that required by the California Building Code for new buildings of similar structure, purpose and location.
CEBC § 105.2 High relevance — show source text
401 A .2 Compliance. The work shall not make the building less complying than it was before the repair was undertaken. Work on nondamaged components that is necessary for the required repair of damaged components shall be considered part of the repair and shall not be subject to requirements for alterations.
401 A .3 Flood hazard areas. In flood hazard areas, repairs that constitute substantial improvement shall require that the building comply with Section 1612 A of the California Building Code .
SECTION 402 A —BUILDING ELEMENTS AND MATERIALS
402 A .1 Glass replacement. The installation or replacement of glass shall be as required for new installations in accordance with the California Building Code.
SECTION 403 A —FIRE PROTECTION
403 A .1 General. Fire protection shall comply with the California Building Standards Code.
SECTION 404 A —MEANS OF EGRESS
404 A .1 General. Repairs shall be done in a manner that maintains the level of protection provided for the means of egress.
SECTION 405 A —STRUCTURAL
405 A .1 General. Structural damage shall be repaired in compliance with this section and Section 401 A .2.
Exception: Routine maintenance required by Chapter 3A, ordinary repairs exempt from permit in accordance with California Building Code Section 105.2, and abatement of wear due to normal service conditions shall not be subject to the requirements for repairs in this section.
405 A .1.1 Structural concrete. Repair of structural concrete shall be permitted to comply with ACI 562 Section 1.7, except where Section 405.2.2, 405.2.3 or 405.2.4.1 requires compliance with Section 304.3.
405 A .2 Repairs to damaged buildings. Repairs to damaged buildings shall comply with this section.
405 A .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. New struc- tural members and connections used for this repair shall comply with the detailing provisions of this code for new buildings of similar structure, purpose and location.
405 A .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 .
405 A .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.
CEBC § 105.2 High relevance — show source text
Exception: Routine maintenance required by Chapter 3A, ordinary repairs exempt from permit in accordance with California Building Code Section 105.2, and abatement of wear due to normal service conditions shall not be subject to the requirements for repairs in this section.
405 A .1.1 Structural concrete. Repair of structural concrete shall be permitted to comply with ACI 562 Section 1.7, except where Section 405.2.2, 405.2.3 or 405.2.4.1 requires compliance with Section 304.3.
405 A .2 Repairs to damaged buildings. Repairs to damaged buildings shall comply with this section.
405 A .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. New struc- tural members and connections used for this repair shall comply with the detailing provisions of this code for new buildings of similar structure, purpose and location.
405 A .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 .
405 A .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.
405 A .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 A .2.3.1, and either repaired in accordance with Section 405 A .2.3.2 or repaired and retrofitted in accordance with Section 405 A .2.3.3, depending on the results of the evaluation.
405 A .2.3.1 Evaluation. The building shall be evaluated by a registered design professional, and the evaluation findings shall be submitted to the building 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 and earthquake effects. Earthquake loads for this evaluation, if required, shall
2025 CALIFORNIA EXISTING BUILDING CODE 4A-3
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REPAIRS
CEBC § 503.11 High relevance — show source text
[BS] 503.11 Substantial structural alteration. Where the work area exceeds 50 percent of the building area and where work involves a substantial structural alteration, the lateral load-resisting system of the altered building shall 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:
- 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 .
- Where the intended alteration involves structural components of the lowest story of a building, only the lateral loadresisting system above that story need not comply with this section.
[BS] 503.12 Roof diaphragms resisting wind loads in high-wind regions. Where the intended alteration requires a permit for reroofing and involves removal of roofing materials from more than 50 percent of the roof diaphragm of a building or section of a building located where the basic wind speed, V, is greater than 130 mph (58 m/s) in accordance with Figure 1609.3(2) of the California
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PRESCRIPTIVE COMPLIANCE METHOD
Building Code, roof diaphragms, connections of the roof diaphragm to roof framing members, and roof-to-wall connections shall be evaluated for the wind loads specified in Section 1609 of the California Building Code, including wind uplift. If the diaphragms and connections in their current condition are not capable of resisting 75 percent of those wind loads, they shall be replaced or strengthened in accordance with the loads specified in Section 1609 of the California Building Code .
Exception: Buildings that have been demonstrated to comply with the wind load provisions in ASCE 7—88 or later editions.
[BS] 503.13 Voluntary lateral force-resisting system alterations. Structural alterations that are intended exclusively to improve the lateral force-resisting system and are not required by other sections of this code shall not be subject to the structural requirements of Section 503, provided that all of the following apply:
- With the alteration complete, the capacity of existing structural systems to resist forces is not reduced.
- New structural elements are detailed and connected to existing or new structural elements as required by the selected design criteria. Exception: New lateral force-resisting systems designed in accordance with the California Building Code are permitted to be of a type designated as “Ordinary” or “Intermediate” where ASCE 7 Table 12.2-1 states these types of systems are not permitted.
- Supports and attachments for nonstructural elements removed and reinstalled to facilitate the work comply with the Cali- fornia Building Code for new construction.
- The alterations do not create a structural irregularity as defined in ASCE 7 or make an existing structural irregularity more
severe.
Frequently asked questions
Who must perform the evaluation after substantial structural damage?
A registered design professional must perform the evaluation and submit the findings to the building official, per § 405.2.3.1.
If the evaluation finds the predamage system is compliant, can I just repair like‑for‑like?
Yes. If the evaluation establishes predamage compliance, the damaged elements may be restored to their predamage condition under § 405.2.3.2.
If retrofit is required, what seismic load level must be used?
Retrofit seismic loads must be at least those required by the building code in effect at the time of original construction, and in no case less than 75% of CBC §1613A, per § 405.2.3.3.
Are one‑ and two‑family homes covered by this requirement?
No — one‑ and two‑family dwellings are excepted from the CEBC evaluation/retrofit requirements for earthquake effects in these sections.
Does foundation damage have to be evaluated?
Yes. § 405.2.3.1 requires the evaluation to include the foundation if the building is to be returned to its predamage state (foundation is part of the lateral system evaluation).
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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