CEBC · California Existing Building Code
How accessibility, flood, and structural exceptions affect method choice
If your project triggers accessibility obligations, is a substantial improvement in a flood hazard area, or exceeds CEBC structural thresholds (like >5% gravity or >10% lateral change, or >50% work area), you cannot rely on simple prescriptive repairs — the CEBC forces full flood design or structural compliance and usually requires the more rigorous Work Area or Performance methods.
Last reviewed: July 6, 2026
What the code requires — plain English
The California Existing Building Code gives three compliance routes — Prescriptive, Work Area, or Performance — and limits when you may rely on exceptions. In short: accessibility requirements may not be avoided, substantial improvements in flood hazard areas must meet new‑construction flood rules, and certain structural triggers (percent increases or scope thresholds) force you to use more rigorous structural provisions or a different compliance method. See § 301 for method selection guidance and the flood/structural cross‑references.
The single most important rule: if an alteration is a substantial improvement in a flood hazard area, it must comply with the flood provisions for new construction (you cannot rely on ordinary exceptions to avoid full flood design). § 503.2.
Requirements in detail
How the three topics constrain method choice (summary)
- Accessibility: Alterations required for accessibility by the California Building Code cannot be avoided by applying an older‑code exception — accessibility work must be done regardless of the chosen CEBC compliance method.
- Flood (substantial improvement): Any alteration that is a substantial improvement in an SFHA (special flood hazard area) must comply with flood‑design requirements for new construction; that requirement can change which CEBC method and which CBC provisions apply. § 503.2.
- Structural triggers: Numeric thresholds and scope triggers in the CEBC force replacement, strengthening, or full compliance with the CBC structural provisions and may require switching to a more rigorous CEBC method (Work Area or Performance). See § 503.3, § 502/503 (lateral exceptions) and § 503.11.
Decision table — key dimensions that change method choice
| Decision dimension | Key numeric/value(s) | Effect on method choice / required action | Code Reference |
|---|---|---|---|
| Flood: is the work a substantial improvement in a mapped flood hazard? | Defined in CEBC Chapter 2 (term used throughout) | If yes, the work must meet flood design for new construction; exceptions are limited — this can force compliance beyond Prescriptive methods. | § 503.2 |
| Gravity load increase from alteration | > 5% increase in design dead/live/snow load | Existing gravity elements must be replaced or altered to meet CBC new‑construction gravity loads — may push project out of simple Prescriptive repair scope. | § 503.3 |
| Lateral demand change (addition/alteration) | Demand‑capacity ratio increase > 10% (else permitted to remain unaltered) | If >10% (or if alteration increases design lateral loads or causes prohibited irregularity), the lateral force‑resisting system must meet CBC lateral requirements — may require Work Area or Performance method. | § 502.4 / § 503.4 |
| Extent of work area | Work area > 50% of building + substantial structural alteration | Lateral system must satisfy CBC lateral load provisions and § 304.3.2 (structural upgrade requirements) — triggers more rigorous structural analysis and possibly Method B or Method C. | § 503.11 and cross‑ref to § 304.3.2 |
| Reroofing in very high‑wind regions | Basic wind speed V > 130 mph and >50% roof diaphragm removal | Diaphragms and connections must be evaluated; if they resist < 75% of specified wind loads, they must be replaced or strengthened (affects which compliance method/specs apply). | § 503.12 |
| Accessibility requirements | Alterations required by CBC Chapter 11A | Accessibility obligations are mandatory and cannot be avoided by choosing an older‑code exception — they must be addressed in whichever CEBC method is used. | § 301 exception / § 301 |
Notes on the table:
- The CEBC uses these numeric triggers to determine whether an alteration can remain relatively limited (Prescriptive) or must be treated with the structural rigour of new construction (Work Area or Performance).
- Where the CEBC cross‑references CBC structural sections (e.g., Section 1609/1613), the relevant CBC loads and detailing apply to the altered building as required by the CEBC section cited.
How each controlling section fits into method choice
§ 503.2 (Flood hazard areas) — If an alteration is a substantial improvement in an identified flood hazard area, the entire project (and aspects of the existing structure) must comply with new‑construction flood design. That requirement overrides permissive exceptions and can force a move from a Prescriptive repair to the more prescriptive‑for‑new‑construction CBC provisions or a method that demonstrates equivalent compliance.
§ 304 (Structural provisions referenced in several places) — Section 304 subsections (notably § 304.3.1 and § 304.3.2) are the structural thresholds and detailing cross‑references that the CEBC uses when alterations affect lateral systems. When the CEBC requires compliance with Section 1609 (wind) or 1613 (seismic) for the lateral system, it also points to § 304.3.1/3.2 for how to treat the existing/altered lateral system. These cross‑references mean that certain structural conditions force a structural compliance path rather than a simple prescriptive repair.
§ 1303.1.3 — This section is cited in CEBC cross‑references (for example in Section 301 exceptions where flood substantial improvement is listed as a trigger), indicating it addresses specific situations where flood provisions or other policy choices affect compliance method selection. The specific text of § 1303.1.3 was referenced by the CEBC excerpts available to me but the full text of § 1303.1.3 was not present in the retrieved files, so I cannot quote its language directly. See the CEBC cross‑reference in § 301.
Exceptions & special cases
Incidental/minor alterations (lateral) — An existing lateral element whose demand‑capacity ratio with the alteration considered is not more than 10% greater than before may remain unaltered; this is an explicit narrow exception and must be calculated using the load combos in the CBC. Do not assume “small” means you can skip analysis — compute the ratio.
Gravity load small increases — Small increases in gravity load up to 5% are tolerated; >5% requires replacement or alteration of existing gravity elements to meet CBC gravity loads.
Voluntary lateral upgrades — If you voluntarily strengthen the lateral system (not required by other CEBC sections) you may be allowed to follow alternative criteria, provided you do not reduce capacity or create new irregularities — but several conditions apply and cross‑refs to § 304A.3.4 are used for detailing. Carefully confirm whether the voluntary work is truly optional under CEBC.
High‑wind reroofing — Where basic wind speed V > 130 mph and reroofing removes >50% of diaphragm area, test diaphragms/connections; if current condition resists < 75% of wind loads, replacement/strengthening is required.
Accessibility and older‑code exception — The CEBC allows, with code‑official approval, that some alterations may comply with the laws at the time the building was originally built, except for accessibility work required now by CBC Chapter 11A (those must be done). Do not rely on an “original‑code” option to avoid accessibility upgrades.
Common mistakes
- Assuming a small scope means you can ignore structural triggers — always check the >5% gravity and >10% lateral D:C thresholds.
- Treating flood zones as optional — if the work is a substantial improvement in a mapped flood hazard, full flood‑design requirements for new construction apply; the code official’s modification authority for flood provisions is tightly constrained. file
- Overlooking accessibility obligations when using older‑code exceptions — accessibility triggers are explicitly excluded from that exception.
- Forgetting scope triggers (like >50% work area) that change structural rules and the required CEBC path.
Worked example — concrete scenario
Scenario: A homeowner will alter 40% of a single‑story apartment building (not historic) in a mapped flood hazard area. The work requires adding mechanical equipment that increases roof dead load by 6% and adds new shear walls that change the demand‑capacity ratio on an existing lateral element by 12%.
Step-by-step code impacts:
Flood: Because the property is in a mapped flood hazard area and the work is within the flood‑area thresholds that make the work a substantial improvement (assume the owner’s scope meets the CEBC definition of substantial improvement), the project must comply with flood design for new construction. That requirement can force design changes that exceed simple Prescriptive repairs. § 503.2.
Gravity loads: The roof dead load increase is 6%, which is >5%, so existing gravity load‑carrying elements must be replaced or altered to meet the CBC gravity requirements for new structures. This alone may make the Prescriptive path infeasible and push the project to a Work Area or Performance method where structural analysis is shown. § 503.3.
Lateral elements: The demand‑capacity ratio increases 12% (over the 10% exception), so the lateral element cannot be left unaltered under the incidental/minor exception; the lateral force‑resisting system must meet CBC lateral provisions and the CEBC structural cross‑references (including § 304.3.x), requiring a structural analysis and probable strengthening. § 502.4 / § 503.4 / § 304.3.2.
Result — method choice and practical consequence:
- Because of the flood substantial improvement requirement and the structural triggers (>5% gravity and >10% lateral), the project will likely not qualify for the simple Prescriptive Compliance Method and will require a Work Area (Method B) or Performance (Method C) approach with structural analysis, demonstration of flood compliance to new‑construction standards, and accessibility provisions as required. Refer to CEBC Section 301 for method selection language.
Related provisions (quick list)
- § 301 — Choice of compliance method; exceptions that reference accessibility and flood triggers.
- § 503.3 — Existing gravity load elements and >5% trigger for replacement/alteration.
- § 502 / § 503.4 — Lateral load treatment and the 10% demand‑capacity exception. file
- § 503.11 — Substantial structural alteration threshold (>50% work area) and lateral system requirements.
- § 503.12 — Roof diaphragm and high‑wind region thresholds (V > 130 mph, 75% capacity rule).
- § 104.2.4.1 — Code‑official modification authority for flood provisions and limiting conditions for granting modifications.
Code references
Grounded in the retrieved California Existing Building Code — click a citation to read the verbatim passage:
CEBC § 3.4 Medium relevance — show source text
Any existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements of Section 502A.4 .
502 A .4 Existing structural elements carrying lateral load. Where the addition is structurally independent of the existing structure, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing structure, the lateral force-resisting system of the existing structure and its addition acting together as a single structure shall comply with Section 1609 A and 1613A of the California Building Code .
Exceptions: For incidental and minor additions:
- Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 A and 1613 A of the California Building Code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction. When calculating demand-capacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 A of the California Building Code or the code wind forces in effect at the time. When calculating demand-capacity ratios for earthquake, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 304A.3.4 of this code or the full seismic forces in effect at the time.
2. Drift limits based on original design code shall be permitted to be used in lieu of the drift limits required by ASCE 7.
SECTION 503 A —ALTERATIONS
503 A .1 General. Alterations to any building or structure shall comply with the requirements of the California Building Code for new construction. Alterations shall be such that the existing building or structure is not less complying with the provisions of the Califor- nia Building Code than the existing building or structure was prior to the alteration.
Exceptions:
- An existing stairway shall not be required to comply with the requirements of Section 1011 of the California Building Code where the existing space and construction does not allow a reduction in pitch or slope.
- Handrails otherwise required to comply with Section 1011.11 of the California Building Code shall not be required to comply with the requirements of Section 1014.7 of the California Building Code regarding full extension of the handrails where such extensions would be hazardous because of plan configuration.
503 A .2 Flood hazard areas. For buildings and structures in flood hazard areas established in Section 1612 A .3 of the California Build- ing Code, any alteration that constitutes substantial improvement of the existing structure , as defined in Chapter 2, shall comply with the flood design requirements for new construction, and all aspects of the existing structure shall be brought into compliance with the requirements for new construction for flood design.
CEBC § 1.1 Medium relevance — show source text
Exception: In-filling of floor openings and nonoccupiable appendages such as elevator and exit stairway shafts shall be permitted beyond that permitted by the California Building Code.
502 A .1.1 Risk category assignment. Where the addition and the existing building have different occupancies, the risk category of each existing and added occupancy shall be determined in accordance with Section 1604 A .5.1 of the California Building Code . Where application of that section results in a higher risk category for the existing building compared with the risk category for the existing building before the addition, such a change shall be considered a change of occupancy and shall comply with Section 506 A of this code. Where application of that section results in a higher risk category for the addition compared with the risk category for the addition by itself, the addition and any systems in the existing building required to serve the addition shall comply with the requirements of the California Building Code for new construction for the higher risk category.
502 A .1.2 Creation or extension of nonconformity. An addition shall not create or extend any nonconformity in the existing building to which the addition is being made with regard to accessibility, structural strength, supports and attachments for nonstructural components, fire safety, means of egress or the capacity of mechanical, plumbing or electrical systems.
Exception: Nonconforming supports and attachments for nonstructural components that serve the addition from within the existing building need not be altered to comply with California Building Code Section 1613 A unless the components are part of the addition’s life-safety system or are required to serve an addition assigned to Risk Category IV.
502 A .2 Flood hazard areas. For buildings and structures in flood hazard areas established in California Building Code, Section 1612 A .3, any addition that constitutes substantial improvement of the existing structure , as defined in Chapter 2, shall comply with the flood design requirements for new construction, and all aspects of the existing structure shall be brought into compliance with
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the requirements for new construction for flood design. For new foundations, foundations raised or extended upward, and replacement foundations, the foundations shall be in compliance with the requirements for new construction for flood design.
For buildings and structures in flood hazard areas established in California Building Code, Section 1612 A .3, any additions that do not constitute substantial improvement of the existing structure , as defined in Chapter 2, are not required to comply with the flood design requirements for new construction, provided that both of the following apply:
- The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
- The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or structure or the lowest floor elevation required in Section 1612 A of the California Building Code .
502 A .3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an addition and its related alterations cause an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures.
CEBC § 1612.3 Medium relevance — show source text
For buildings and structures in flood hazard areas established in Section 1612.3 of the California Building Code, or Section R322 of the California Residential Code, as applicable, any additions that do not constitute substantial improvement of the existing structure are not required to comply with the flood design requirements for new construction, provided that both of the following apply:
- The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
- The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or structure or the lowest floor elevation required in Section 1612 of the California Building Code or Section R306 of the California Residential Code, as applicable.
[BS] 502.3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an addition and its related alterations cause an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity load-carrying structural element whose vertical load-carrying capacity is decreased as part of the addition and its related alterations shall be considered to be an altered element subject to the requirements of Section 503.3. Any existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements of Section 502.3.
Exception: Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes where the existing building and the addition together comply with the conventional light-frame construction methods of the Cali- fornia Building Code or the provisions of the California Residential Code .
[BS] 502.4 Existing structural elements carrying lateral load. Where the addition is structurally independent of the existing structure, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing structure, the lateral force-resisting system of the existing structure and its addition acting together as a single structure shall comply with Section 1609 of the California Building Code and with Section 304.3.1 of this code.
Exceptions:
- Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 and 1613 of the California Building Code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction. When calcu
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CEBC § 503.11 Medium 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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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.
CEBC § 1011.11 Medium relevance — show source text
Exceptions:
- An existing stairway shall not be required to comply with the requirements of Section 1011 of the California Building Code where the existing space and construction does not allow a reduction in pitch or slope.
- Handrails otherwise required to comply with Section 1011.11 of the California Building Code shall not be required to comply with the requirements of Section 1014.7 of the California Building Code regarding full extension of the handrails where such extensions would be hazardous because of plan configuration.
- Where provided in below-grade transportation stations, existing and new escalators shall be permitted to have a clear width of less than 32 inches (815 mm). 4. [BSC] For state-owned buildings, including those owned by the University of California and the California State University and the judicial council, the requirements of Section 503.4 are replaced by the requirements of Sections 317 through 322.
[BS] 503.2 Flood hazard areas. For buildings and structures in flood hazard areas established in Section 1612.3 of the California Building Code, or Section R306 of the California Residential Code, as applicable, any alteration that constitutes substantial improvement of the existing structure shall comply with the flood design requirements for new construction, and all aspects of the existing structure shall be brought into compliance with the requirements for new construction for flood design.
For buildings and structures in flood hazard areas established in Section 1612.3 of the California Building Code, or Section R306 of the California Residential Code, as applicable, any alterations that do not constitute substantial improvement of the existing structure are not required to comply with the flood design requirements for new construction.
[BS] 503.3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an alteration causes an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity load-carrying structural element whose gravity load-carrying capacity is decreased as part of the alteration shall be shown to have the capacity to resist the applicable design dead, live and snow loads including snow drift effects required by the California Building Code for new structures.
Exceptions:
- Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes where the altered building complies with the conventional light-frame construction methods of the California Building Code or the provisions of the California Residential Code .
- Buildings in which the increased dead load is due entirely to the addition of a second layer of roof covering weighing 3 pounds per square foot (0.1437 kN/m [2] ) or less over an existing single layer of roof covering. [DSA-SS, DSA-SS/CC] Excep- tion 2 is not permitted.
[BS] 503.4 Existing structural elements carrying lateral load. Except as permitted by Section 503.13, where the alteration increases design lateral loads, results in a prohibited structural irregularity as defined in ASCE 7, or decreases the capacity of any existing lateral load-carrying structural element, the lateral force-resisting system of the altered building or structure shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code.
Exceptions:
CEBC § 5A-4 Medium relevance — show source text
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the requirements for new construction for flood design. For new foundations, foundations raised or extended upward, and replacement foundations, the foundations shall be in compliance with the requirements for new construction for flood design.
For buildings and structures in flood hazard areas established in California Building Code, Section 1612 A .3, any additions that do not constitute substantial improvement of the existing structure , as defined in Chapter 2, are not required to comply with the flood design requirements for new construction, provided that both of the following apply:
- The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
- The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or structure or the lowest floor elevation required in Section 1612 A of the California Building Code .
502 A .3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an addition and its related alterations cause an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity load-carrying structural element whose vertical load-carrying capacity is decreased as part of the addition and its related alterations shall be considered to be an altered element subject to the requirements of Section 503 A .3. Any existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements of Section 502A.4 .
502 A .4 Existing structural elements carrying lateral load. Where the addition is structurally independent of the existing structure, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing structure, the lateral force-resisting system of the existing structure and its addition acting together as a single structure shall comply with Section 1609 A and 1613A of the California Building Code .
Exceptions: For incidental and minor additions:
- Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 A and 1613 A of the California Building Code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction. When calculating demand-capacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 A of the California Building Code or the code wind forces in effect at the time.
CEBC § 104.2.3.6.2 Medium relevance — show source text
[A] 104.2.3.6.2 Other reports. Reports not complying with Section 104.2.3.6.1 shall describe criteria, including but not limited to any referenced testing or analysis, used to determine compliance with code intent and justify code equivalence. The report shall be prepared by a qualified engineer, specialist, laboratory or fire safety specialty organization acceptable to the code official. The code official is authorized to require design submittals to be prepared by, and bear the stamp of, a registered design professional.
[A] 104.2.3.7 Peer review. The code official is authorized to require submittal of a peer review report in conjunction with a request to use an alternative material, design or method of construction, prepared by a peer reviewer that is approved by the code official.
[A] 104.2.4 Modifications. Where there are practical difficulties involved in carrying out the provisions of this code, the code official shall have the authority to grant modifications for individual cases, provided that the code official shall first find that one or more special individual reasons make the strict letter of this code impractical, and that the modification is in compliance with the intent and purpose of this code and that such modification does not lessen health, accessibility, life and fire safety, or structural requirements. The details of the written request for and action granting modifications shall be recorded and entered in the files of the department of building safety.
[A] 104.2.4.1 Flood hazard areas. For existing buildings located in flood hazard areas for which repairs, alterations and additions constitute substantial improvement, the code official shall not grant modifications to provisions related to flood resistance unless a determination is made that:
The applicant has presented good and sufficient cause that the unique characteristics of the size, configuration or topography of the site render compliance with the flood-resistant construction provisions inappropriate.
Failure to grant the modification would result in exceptional hardship.
The granting of the modification will not result in increased flood heights, additional threats to public safety or extraordinary public expense; create nuisances; cause fraud on or victimization of the public; or conflict with existing laws or ordinances.
The modification is the minimum necessary to afford relief, considering the flood hazard.
A written notice will be provided to the applicant specifying, if applicable, the difference between the design flood elevation and the elevation to which the building is to be built, stating that the cost of flood insurance will be
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commensurate with the increased risk resulting from the reduced floor elevation and that construction below the design flood elevation increases risks to life and property.
[A] 104.3 Applications and permits. The code official shall receive applications, review construction documents, issue permits, inspect the premises for which such permits have been issued and enforce compliance with the provisions of this code.
CEBC § 502.1.1 Medium relevance — show source text
502.1.1 Risk category assignment. Where the addition and the existing building have different occupancies, the risk category of each existing and added occupancy shall be determined in accordance with Section 1604.5.1 of the California Building Code . Where application of that section results in a higher risk category for the existing building compared with the risk category for the existing building before the addition, such a change shall be considered a change of occupancy and shall comply with Section 506 of this code. Where application of that section results in a higher risk category for the addition compared with the risk category for the addition by itself, the addition and any systems in the existing building required to serve the addition shall comply with the requirements of the California Building Code for new construction for the higher risk category.
502.1.2 Creation or extension of nonconformity. An addition shall not create or extend any nonconformity in the existing building to which the addition is being made with regard to accessibility, structural strength, supports and attachments for nonstructural components, fire safety, means of egress or the capacity of mechanical, plumbing or electrical systems.
Exception: Nonconforming supports and attachments for nonstructural components that serve the addition from within the existing building need not be altered to comply with California Building Code Section 1613 unless the components are part of the addition’s life-safety system or are required to serve an addition assigned to Risk Category IV.
[BS] 502.2 Flood hazard areas. For buildings and structures in flood hazard areas established in Section 1612.3 of the California Building Code, or Section R322 of the California Residential Code, as applicable, any addition that constitutes substantial improvement of the existing structure shall comply with the flood design requirements for new construction, and all aspects of the existing structure shall be brought into compliance with the requirements for new construction for flood design. For new foundations, foundations raised or extended upward, and replacement foundations, the foundations shall be in compliance with the requirements for new construction for flood design.
For buildings and structures in flood hazard areas established in Section 1612.3 of the California Building Code, or Section R322 of the California Residential Code, as applicable, any additions that do not constitute substantial improvement of the existing structure are not required to comply with the flood design requirements for new construction, provided that both of the following apply:
- The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
- The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or structure or the lowest floor elevation required in Section 1612 of the California Building Code or Section R306 of the California Residential Code, as applicable.
[BS] 502.3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an addition and its related alterations cause an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity load-carrying structural element whose vertical load-carrying capacity is decreased as part of the addition and its related alterations shall be considered to be an altered element subject to the requirements of Section 503.3. Any existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements o
CEBC § 1402.2 Medium relevance — show source text
[BS] 1402.2 Foundation. The foundation system of relocated buildings shall comply with the California Building Code or the Califor- nia Residential Code, as applicable.
[BS] 1402.2.1 Connection to the foundation. The connection of the relocated building to the foundation shall comply with the California Building Code or the California Residential Code, as applicable.
[BS] 1402.3 Wind loads. Buildings shall comply with California Building Code or California Residential Code wind provisions, as applicable.
Exceptions:
- Detached one- and two-family dwellings and Group U occupancies where wind loads at the new location are not higher than those at the previous location.
- Structural elements whose stress is not increased by more than 10 percent.
[BS] 1402.4 Seismic loads. Buildings shall comply with California Building Code or California Residential Code seismic provisions at the new location, as applicable.
Exceptions:
- Structures in Seismic Design Categories A and B and detached one- and two-family dwellings in Seismic Design Categories A, B and C where the seismic loads at the new location are not higher than those at the previous location.
- Structural elements whose stress is not increased by more than 10 percent.
[BS] 1402.5 Snow loads. Structures shall comply with California Building Code or California Residential Code snow loads, as applicable, where snow loads at the new location are higher than those at the previous location.
Exception: Structural elements whose stress is not increased by more than 5 percent.
[BS] 1402.6 Flood hazard areas. If relocated or moved into a flood hazard area, structures shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
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RELOCATED OR MOVED BUILDINGS
[BS] 1402.7 Required inspection and repairs. The code official shall be authorized to inspect, or to require approved professionals to inspect at the expense of the owner, the various structural parts of a relocated building to verify that structural components and connections have not sustained structural damage. Any repairs required by the code official as a result of such inspection shall be made prior to the final approval.
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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE
CHAPTER 15 – CONSTRUCTION SAFEGUARDS
(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
Adopting Agency BSC BSC-
CGSFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC Adopting CBC § 301 Medium relevance — show source text
This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:
Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).
Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area Compliance Method given in Chapters 6 through 12.
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Option 3: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Performance Compliance Method given in Chapter 13. It should be noted that this option was also provided in the former Chapter 34 of the IBC (2012 and earlier editions).
Under limited circumstances, a building alteration can be made to comply with the laws under which the building was originally built, as long as the accessibility requirements are met, there has been no substantial structural damage and there will be limited structural alteration. Flood hazard provisions also must still be addressed where there is a substantial improvement.
Note that all repairs must comply with Chapter 4 and all relocated buildings are addressed by Chapter 14.
ARRANGEMENT AND FORMAT OF THE 2025 CEBC
The format of the CEBC allows each chapter to be devoted to a particular subject. The following table shows how the CEBC is divided. The subsequent table shows CEBC requirements that are correlated with other California Codes. The chapter synopses detail the scope and intent of the provisions of the CEBC.
CHAPTER TOPICS Col2 CHAPTER SUBJECTS 1, 2 Administrative Requirements and Definitions 3 Provisions for all Compliance Methods 4 Repairs 5 Prescriptive Compliance Method for Existing Buildings 6–11 Work Area Compliance Method for Existing Buildings 13 Performance Compliance Method for Existing Buildings 14 Relocated Buildings 15 Construction Safeguards 16 Referenced Standards Appendix A Guidelines for Seismic Retrofit of Existing Buildings Appendix B Supplementary Accessibility Requirements for Existing Buildings Appendix C Guidelines for Wind Retrofit of Existing Buildings Appendix D Board of Appeals Appendix E Temporary Emergency Uses Resource A Guidelines on Fire Ratings of Archaic Materials and Assemblies CALIFORNIA BUILDING CODE CORRELATED TOPICS
The CEBC requirements for construction safeguards are directly correlated to the requirements of the CBC. The following table shows chapters of the CBC that are correlated with the CEBC:
CEBC/CBC CORRELATED TOPICS Col2 Col3 CEBC CHAPTER/SECTION CBC CHAPTER/SECTION SUBJECT Chapter 15 Chapter 33 Construction safeguards Chapter 1 Scope and Administration.
Chapter 1 establishes the limits of applicability of the code and describes how the code is to be applied and enforced. The provisions of Chapter 1 establish the authority and duties of the code official appointed by the authority having jurisdiction and also establish the rights and privileges of the design professional, contractor and property owner.
Chapter 2 Definitions.
CBC § 301 Medium relevance — show source text
The IEBC is a model code in the International Code family of codes intended to provide requirements for repair and alternative approaches for alterations, changes of occupancy and additions to existing buildings. A large number of existing buildings and structures do not comply with the current building code requirements for new construction. Although many of these buildings are potentially salvageable, rehabilitation is often cost-prohibitive because compliance with all the requirements for new construction could require extensive changes that go well beyond the value of the building or the original scope of the alteration. At the same time, it is necessary to regulate construction in existing buildings that undergo additions, alterations, extensive repairs or change of occupancy. Such activity represents an opportunity to ensure that new construction complies with the current building codes and that existing conditions are maintained, at a minimum, to their current level of compliance or are improved as required to meet basic safety levels. To accomplish this objective, and to make the alteration process easier, this code allows for options for controlled departure from full compliance with the International Codes dealing with new construction, while maintaining basic levels for fire safety, structural and life safety features of the rehabilitated building.
This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:
Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).
Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area Compliance Method given in Chapters 6 through 12.
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Option 3: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Performance Compliance Method given in Chapter 13. It should be noted that this option was also provided in the former Chapter 34 of the IBC (2012 and earlier editions).
Under limited circumstances, a building alteration can be made to comply with the laws under which the building was originally built, as long as the accessibility requirements are met, there has been no substantial structural damage and there will be limited structural alteration. Flood hazard provisions also must still be addressed where there is a substantial improvement.
Note that all repairs must comply with Chapter 4 and all relocated buildings are addressed by Chapter 14.
ARRANGEMENT AND FORMAT OF THE 2025 CEBC
The format of the CEBC allows each chapter to be devoted to a particular subject. The following table shows how the CEBC is divided. The subsequent table shows CEBC requirements that are correlated with other California Codes. The chapter synopses detail the scope and intent of the provisions of the CEBC.
CEBC § 105.2 Medium 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 § 1011.11 Medium relevance — show source text
2. Drift limits based on original design code shall be permitted to be used in lieu of the drift limits required by ASCE 7.
SECTION 503 A —ALTERATIONS
503 A .1 General. Alterations to any building or structure shall comply with the requirements of the California Building Code for new construction. Alterations shall be such that the existing building or structure is not less complying with the provisions of the Califor- nia Building Code than the existing building or structure was prior to the alteration.
Exceptions:
- An existing stairway shall not be required to comply with the requirements of Section 1011 of the California Building Code where the existing space and construction does not allow a reduction in pitch or slope.
- Handrails otherwise required to comply with Section 1011.11 of the California Building Code shall not be required to comply with the requirements of Section 1014.7 of the California Building Code regarding full extension of the handrails where such extensions would be hazardous because of plan configuration.
503 A .2 Flood hazard areas. For buildings and structures in flood hazard areas established in Section 1612 A .3 of the California Build- ing Code, any alteration that constitutes substantial improvement of the existing structure , as defined in Chapter 2, shall comply with the flood design requirements for new construction, and all aspects of the existing structure shall be brought into compliance with the requirements for new construction for flood design.
For buildings and structures in flood hazard areas established in Section 1612 A .3 of the California Building Code any alterations that do not constitute substantial improvement of the existing structure , as defined in Chapter 2, are not required to comply with the flood design requirements for new construction.
503 A .3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an alteration causes an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity loadcarrying structural element whose gravity load-carrying capacity is decreased as part of the alteration shall be shown to have the capacity to resist the applicable design dead, live and snow loads including snow drift effects required by the California Building Code for new structures.
503 A .4 Existing structural elements carrying lateral load. Except as permitted by Section 503 A .13, where the alteration increases design lateral loads, results in a prohibited structural irregularity as defined in the California Building Code, ASCE 7, or decreases the
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PRESCRIPTIVE COMPLIANCE METHOD
capacity of any existing lateral load-carrying structural element, the lateral force-resisting system of the altered building or structure shall meet the requirements of Section s 1609 A and 1613A of the California Building Code .
Exceptions: For incidental and minor alterations:
- Any existing lateral load-carrying structural element whose demand-capacity ratio with the alteration considered is not more than 10 percent greater than its demand-capacity ratio with the alteration ignored shall be permitted to remain unaltered.
CEBC § 3-3 Medium relevance — show source text
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PROVISIONS FOR ALL COMPLIANCE METHODS
members added as part of the alteration shall comply with the California Building Code . This exception shall not apply to the following:
Alterations for accessibility required by the California Building Code, Chapter 11A.
Alterations that constitute substantial improvement in flood hazard areas, which shall comply with Sections 503.2, 701.3 or 1303.1.3.
Structural provisions of Section 304, Chapter 5 or to the structural provisions of Sections 706, 805 and 906.
301.3.1 Prescriptive compliance. Alterations, additions and changes of occupancy complying with Chapter 5 of this code in buildings complying with the California Fire Code shall be considered in compliance with the provisions of this code.
Exception: Hospital buildings removed from acute care service, skilled nursing facilities, intermediate-care facilities, correctional treatment centers and acute psychiatric hospitals [OSHPD 1R, 2, 4 and 5]. The provisions of adopted sections in Chapters 3 through 5 shall control the alteration, repair and change of occupancy or function of existing structures for applications listed in Section 1.10.1, 1.10.2, 1.10.4 and 1.10.5 regulated by the Department of Health Care Access and Information/Office of Statewide Hospital Planning and Development (OSHPD). Refer to Chapter 3A for services, systems and utilities that serve OSHPD 1 buildings.
301.3.2 Work area compliance method. A lterations, additions and changes of occupancy complying with the applicable requirements of Chapters 6 through 12 of this code shall be considered in compliance with the provisions of this code.
301.3.3 Performance compliance method. Alterations, additions and changes of occupancy complying with Chapter 13 of this code shall be considered in compliance with the provisions of this code.
Note: [HCD 1 & HCD 2] The provisions contained in Chapter 13 are not adopted by HCD, but may be available for adoption by a local ordinance. (See Section 1.1.11.)
301.4 Relocated or moved buildings. Relocated or moved buildings shall comply with the requirements of Chapter 14.
SECTION 302—GENERAL PROVISIONS
302.1 Dangerous conditions. The code official shall have the authority to require the elimination of conditions deemed dangerous.
302.1.1 Dangerous conditions. [BSC] Regardless of the extent of structural or nonstructural damage, the code official shall have the authority to require the elimination of conditions deemed dangerous.
302.2 Additional codes. Alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall comply with the provisions for alterations, repairs, additions and changes of occupancy or relocation, respectively, in this code and the California Energy Code, California Fire Code, California Mechanical Code, California Plumbing Code, California Residential Code and California Electrical Code . Where provisions of the other codes conflict with provisions of this code, the provisions of this code shall take precedence.
Frequently asked questions
When does a flood issue force me out of the Prescriptive Compliance Method?
If the work is a substantial improvement in a flood hazard area, the CEBC requires compliance with flood design for new construction and this can make Prescriptive repairs insufficient. § 503.2.
What are the numeric triggers I must check for structural work?
Check: >5% increase in gravity load (gravity elements must be replaced/altered) and >10% increase in lateral demand‑capacity ratio (lateral elements may no longer be left unaltered). § 503.3; § 502.4/503.4. file
Can I avoid accessibility upgrades by saying I’ll use the original building code?
No. The CEBC’s allowance to comply with laws in force at original construction expressly excludes accessibility work required by CBC Chapter 11A. § 301 exception.
If I voluntarily upgrade seismic capacity, do I have to meet all structural rules?
Voluntary lateral upgrades are permitted under limitations, but the CEBC requires that capacity is not reduced, new elements be detailed per the chosen criteria, and you avoid creating irregularities. Review the voluntary alteration conditions in § 503.13.
Where can I find the CEBC rules that tell me which method (Prescriptive/Work Area/Performance) to use?
Section § 301 sets out the three allowed methods and related exceptions. Use it first to determine method choice, then apply the structural and flood triggers described above.
I see references to § 1303.1.3 — what does it say about flood work?
The CEBC references § 1303.1.3 as a cross‑reference for flood/substantial‑improvement situations (for example in Section 301 exceptions). However, the specific text of § 1303.1.3 was not present in the retrieved excerpts I reviewed, so I could not cite its exact language here. See Section § 301 for the cross‑reference.
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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