CEBC · California Existing Building Code
When do addition provisions apply and do additions follow new-construction rules?
Plain-English summary: Under the CEBC, an addition is generally treated like new construction — you must apply the IBC/IRC rules to the addition and ensure the combined height and area of the existing building plus the addition do not exceed IBC Chapter 5 limits. A compliant firewall can allow the addition to be treated as a separate building, and limited exceptions exist for nonoccupiable appendages and certain flood or small-residential cases. See **§ 1302.1.3** and **§ 1101.1** for the controlling rules.
Last reviewed: July 6, 2026
What the code requires — plain English
An addition to an existing building must generally be built to the same rules that apply to new construction — i.e., follow the IBC or IRC provisions for new buildings — and the combined height and area of the existing building plus the addition may not exceed what Chapter 5 of the International Building Code allows. This is the basic rule in § 1302.1.3. The CEBC’s Chapter 11 further clarifies that an addition is treated as new construction for most purposes and describes limited exceptions and interactions with the existing building; see § 1101.1.
The single most important rule: an addition is treated as new construction for code requirements unless a specific CEBC exception applies — and you must check the combined height/area limit in the IBC for the whole building. (§ 1302.1.3; § 1101.1)
Requirements in detail
Short summary of the two controlling sections
§ 1302.1.3 — Additions. “Additions to existing buildings shall comply with the requirements of the International Building Code or the International Residential Code for new construction. The combined height and area of the existing building and the new addition shall not exceed the height and area allowed by Chapter 5 of the IBC. Where a fire wall meeting IBC §706 is placed between the addition and existing building, the addition is considered a separate building.”
§ 1101.1 — Scope (Chapter 11). “An addition shall comply with the California Building Standards Codes as adopted for new construction without requiring the existing building to comply with new-construction requirements, except as required in this chapter. The provisions of height and area apply to the entire existing building with the additions.”
Decision-relevant dimensions (quick reference table)
| Decision dimension | What to check / value to compute | How CEBC tells you to use it | Code Reference |
|---|---|---|---|
| Whether work is an Addition | Is the work an extension/increase in floor area, number of stories, or height, structurally attached? | If yes, treat under the additions rules | § 1101.1 |
| Applicable construction rules | Use the IBC or IRC requirements for new construction for the addition | Additions must comply with new-construction requirements | § 1302.1.3 |
| Combined height and area | Combined existing + addition height/area (compute) | Must not exceed the allowable per Chapter 5 of the IBC (compare to allowed by occupancy & construction type) | § 1302.1.3 |
| Firewall separation | Is there an IBC §706-compliant firewall between addition and existing building? | If yes, addition = separate building (Chapter 5 limits apply to each building separately) | § 1302.1.3 |
| Impact on existing building | Does the addition or its systems affect the existing building (eg., risk category, life-safety systems, lateral loads)? | If the addition impacts existing building systems or raises risk category the code imposes additional compliance (see §1101.2/1101.3) | § 1101.2 and § 1101.3 |
| Flood hazard / substantial improvement | Does the addition constitute substantial improvement or is in a flood hazard area? | Flood-design requirements for new construction may apply; CEBC has specific conditions and exceptions | § 1303.1.3 and § 1103.3 |
How to apply the rule, step-by-step
- Confirm the work is an addition (increase in area/stories/height, structurally attached). If not, use the appropriate alterations/repair rules.
- Treat the addition as new construction (apply IBC/IRC provisions for the addition itself). § 1302.1.3 requires this.
- Compute the combined height and area (existing building + addition). Compare that combined value to the allowable height and area for the building’s occupancy and construction type per Chapter 5 of the IBC. If the combined value is within the IBC limits, proceed. § 1302.1.3.
- If the combined height/area exceeds IBC Chapter 5 limits, either: (a) reduce the addition size, (b) change occupancy/finish/ construction type to gain allowable area per IBC, or (c) provide an IBC §706-compliant fire wall that separates the new construction so it is treated as a separate building (then size limits apply separately). § 1302.1.3.
- Evaluate whether the addition changes the risk category (different occupancies or increased hazard). If risk category for the existing building increases as a result, a change of occupancy provisions may be triggered; if the addition’s risk category is higher, the addition and any existing systems required to serve it must comply with CBC new-construction rules for that higher risk category. § 1101.3.
Exceptions & special cases
Nonoccupiable appendages & infilling of openings. CEBC permits infilling of floor openings and nonoccupiable appendages (e.g., elevator and stair shafts) beyond what the IBC would permit, as an exception to the addition = new-construction rule. See § 1302.1.3 (Exception).
Firewall separation makes the addition “separate building.” If an IBC §706-compliant firewall is provided between the addition and the existing building, the addition is considered a separate building for the Chapter 5 height/area calculation. § 1302.1.3.
Flood hazard / substantial improvement rules. For additions in flood hazard areas, substantial improvement rules may require bringing the existing building and addition into compliance with flood design for new construction (see CEBC flood provisions and cross-references to IBC §1612 / IRC R306). There are limited circumstances where a structurally connected horizontal addition that is not a substantial improvement may be excepted — but specific conditions must be met (CEBC §1303.1.3 and §1103.3).
Residential light-frame exception. Certain small Group R buildings constructed with conventional light-frame methods have limited exceptions (see CEBC exceptions in Chapter 11).
Energy-code and other code cross-references. Additions must also meet applicable California Energy Code (Part 6) provisions and other referenced codes for the scope of the work; the CEBC points to these cross-code requirements (see CEBC §1104.1 and the Energy Code).
Common mistakes
Assuming an addition never triggers new-construction rules. The CEBC explicitly requires additions to comply with new-construction provisions (IBC/IRC) unless a specific CEBC exception applies (see § 1302.1.3).
Forgetting to calculate combined height/area. The limit is not just the addition alone — you must add the existing building area/height to the proposed addition and compare to IBC Chapter 5. § 1302.1.3 and § 1101.1.
Overlooking firewall option. Providing an IBC §706 firewall can allow the addition to be treated as a separate building (and avoid combining areas) — many designers miss this path. § 1302.1.3.
Not checking effects on existing building systems or risk category. An addition that impacts the existing building’s life-safety systems or changes risk category can trigger broader compliance obligations per § 1101.2 / § 1101.3.
Ignoring flood/substantial improvement conditions. In flood hazard areas, adding area can trigger flood-design requirements for new construction; don’t assume the addition is automatically exempt. See CEBC flood provisions.
Worked example — concrete scenario
Scenario: You have an existing two-story office building (Group B) with existing gross floor area = 8,000 sq ft and existing height = 24 ft. You propose a horizontal attached addition of 3,000 sq ft and one new occupiable floor that increases height by 12 ft.
Steps
- Confirm this is an addition (it increases floor area and adds occupied story) — treat as addition per § 1101.1.
- Compute combined totals: combined floor area = 8,000 + 3,000 = 11,000 sq ft; combined height = 24 + 12 = 36 ft.
- Compare combined values to the allowable height and area in Chapter 5 of the IBC for the building’s occupancy (Group B) and proposed construction type. If Chapter 5 allowable area for the building (by occupancy and construction type) is ≥ 11,000 sq ft and allowable height is ≥ 36 ft, the addition is permitted (subject to complying with new-construction requirements for the addition). If not, you must either reduce the addition, change construction/occupancy classification, or provide a compliant IBC §706 firewall between the addition and the existing building so the addition can be treated as a separate building. This decision path follows § 1302.1.3 and § 1101.1.
Notes: Do not invent IBC Chapter 5 numeric allowances here — consult Chapter 5 of the IBC for allowable area/height by occupancy and construction type, then apply the CEBC guidance above.
Related provisions (quick links)
- § 1302.1.3 — Additions: new-construction rules; combined height/area; firewall separation.
- § 1101.1 — Chapter 11 scope: additions comply with new-construction CBC/CRC as adopted; height/area apply to entire building.
- § 1101.2 — Additions shall not create/extend nonconformity (accessibility, structural, egress, systems).
- § 1101.3 — Risk category assignment when occupancies differ; possible change-of-occupancy consequences.
- § 1303.1.3 — Flood hazard considerations and when additions trigger flood-design requirements.
- Chapter 11 (Additions) general provisions and exceptions — see CEBC Chapter 11 (Section 1101 et seq.).
- CEBC Chapter 6–12 references for work-area methods and related compliance options.
Code references
Grounded in the retrieved California Existing Building Code — click a citation to read the verbatim passage:
CEBC § 1302.1 High relevance — show source text
SECTION 1302—APPLICABILITY
1302.1 General. Existing buildings in which there is work involving additions, alterations or changes of occupancy shall be made to conform to the requirements of this chapter or the provisions of Chapters 6 through 12. The provisions of Sections 1302.1.1 through 1302.1.6 shall apply to existing occupancies that will continue to be, or are proposed to be, in Groups A, B, E, F, I-2, M, R and S. These provisions shall also apply to Group U occupancies where such occupancies are undergoing a change of occupancy or a partial change in occupancy with separations in accordance with Section 1302.1.2. These provisions shall not apply to buildings with occupancies in Group H, I-1, I-3 or I-4.
1302.1.1 Change in occupancy. Where an existing building is changed to a new occupancy classification and this section is applicable, the provisions of this section for the new occupancy shall be used to determine compliance with this code.
1302.1.2 Partial change in occupancy. Where a portion of the building is changed to a new occupancy classification and that portion is separated from the remainder of the building with fire barrier or horizontal assemblies having a fire-resistance rating as required by Table 508.4 of the International Building Code or Section R302 of the International Residential Code for the separate occupancies, or with approved compliance alternatives, the portion changed shall be made to conform to the provisions of this section. Only the portion separated shall be required to be evaluated for compliance.
Where a portion of the building is changed to a new occupancy classification and that portion is not separated from the remainder of the building with fire barriers or horizontal assemblies having a fire-resistance rating as required by Table 508.4 of the International Building Code or Section R302 of the International Residential Code for the separate occupancies, or with approved compliance alternatives, the provisions of this section which apply to each occupancy shall apply to the entire building. Where there are conflicting provisions, those requirements which secure the greater public safety shall apply to the entire building or structure.
1302.1.3 Additions. Additions to existing buildings shall comply with the requirements of the International Building Code or the International Residential Code for new construction. The combined height and area of the existing building and the new addition shall not exceed the height and area allowed by Chapter 5 of the International Building Code . Where a fire wall that complies with Section 706 of the International Building Code is provided between the addition and the existing building, the addition shall be considered a separate building. Where a new occupiable roof is added to a building or structure, the occupiable roof shall comply with the provisions of the International Building Code .
Exception: In-filling of floor openings and nonoccupiable appendages, such as elevator and exit stairway shafts, shall be permitted beyond that permitted by the International Building Code .
1302.1.4 Alterations. An existing building or portion thereof shall not be altered in such a manner that results in the building being less safe or sanitary than such building is currently.
Exception: Where the current level of safety or sanitation is proposed to be reduced, the portion altered shall conform to the requirements of the International Building Code .
1302.1.5 Escalators. Where escalators are 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).
CEBC § 1.3 High relevance — show source text
SECTION BO106—ADDITION
BO106.1 General. Where existing buildings with the addition are within the scope of this code, additions shall comply with this section and other applicable provisions of this code for new construction or as permitted by this appendix. Engineered design in accordance with Section R301.1.3 shall be permitted to meet the requirements of this section.
BO106.2 Structure for horizontal additions. Where an addition involves new construction attached to an existing building, the new construction shall meet all of the structural requirements of this code for new construction. Alterations to the existing building shall comply with the requirements governing alterations within this code. In wood light-frame additions, connection of the structural components shall be permitted to be provided using wall top plates and addition studs that abut the existing building. Wall top plates shall be lapped and spliced in accordance with Section R602.3.2. Abutting studs shall be fastened in accordance with Table R602.3(1).
Exception: The addition structure shall be permitted to be connected to the existing building in accordance with accepted engineering practice.
BO106.3 Structure for vertical additions. Where an addition involves new construction that adds a story to any part of the existing building or vertically increases the height of any part of the existing building, the new construction and the existing building together shall be shown to comply with, or altered to comply with, all of the structural requirements of this code for new construction.
Exception: Where the new structure and the existing structure together are evaluated in accordance with accepted engineering practice and are shown to be sufficient to support the combined loads from the new structure and existing structure, no structural alterations are required.
SECTION BO107—RELOCATED BUILDINGS
BO107.1 General. Residential buildings or structures moved into or within the jurisdiction are not required to comply with the requirements for new construction under this code, provided they comply with all of the following conditions:
The building shall be safe for human occupancy as determined by the California Fire Code and the International Property Maintenance Code .
Any repair, alteration or change of use undertaken within the relocated structure shall comply with the requirements of this code applicable to the work being performed.
Any field fabricated elements shall comply with the applicable requirements of this code.
SECTION BO108—REFERENCED STANDARDS
BO108.1 General. See Table BO108.1 for standards that are referenced in various sections of this appendix. Standards are listed by the standard identification with the effective date, the standard title and the section or sections of this appendix that reference the standard.
TABLE BO108.1—REFERENCED STANDARDS Col2 Col3 STANDARD ACRONYM STANDARD NAME SECTION HEREIN REFERENCED CEBC—25 California Existing Building Code BO102.8 CFC—25 California Fire Code BO107.1 IPMC—24 International Property Maintenance Code® BO107.1 APPENDIX BO-6 2025 CALIFORNIA RESIDENTIAL CODE
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CA RESERVED
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APPENDIX CA-2 2025 CALIFORNIA RESIDENTIAL CODE
CEBC § 1302.1.3 High relevance — show source text
1302.1.3 Additions. Additions to existing buildings shall comply with the requirements of the International Building Code or the International Residential Code for new construction. The combined height and area of the existing building and the new addition shall not exceed the height and area allowed by Chapter 5 of the International Building Code . Where a fire wall that complies with Section 706 of the International Building Code is provided between the addition and the existing building, the addition shall be considered a separate building. Where a new occupiable roof is added to a building or structure, the occupiable roof shall comply with the provisions of the International Building Code .
Exception: In-filling of floor openings and nonoccupiable appendages, such as elevator and exit stairway shafts, shall be permitted beyond that permitted by the International Building Code .
1302.1.4 Alterations. An existing building or portion thereof shall not be altered in such a manner that results in the building being less safe or sanitary than such building is currently.
Exception: Where the current level of safety or sanitation is proposed to be reduced, the portion altered shall conform to the requirements of the International Building Code .
1302.1.5 Escalators. Where escalators are 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).
1302.1.6 Plumbing fixtures. Plumbing fixtures shall be provided in accordance with Section 1009 for a change of occupancy and Section 808 for alterations. Plumbing fixtures for additions shall be in accordance with the International Plumbing Code .
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PERFORMANCE COMPLIANCE METHODS
SECTION 1303—ACCEPTANCE
1303.1 General. For repairs, alterations, additions and changes of occupancy to existing buildings that are evaluated in accordance with this section, compliance with this section shall be accepted by the code official.
1303.1.1 Hazards. Where the code official determines that an unsafe condition exists as provided for in Section 115, such unsafe condition shall be abated in accordance with Section 115.
1303.1.2 Compliance with other codes. Buildings that are evaluated in accordance with this section shall comply with the Inter- national Fire Code and International Property Maintenance Code .
[BS] 1303.1.3 Compliance with flood hazard provisions. In flood hazard areas, buildings that are evaluated in accordance with this section shall comply with Section 1612 of the International Building Code, or Section R306 of the International Residential Code, as applicable, if the work covered by this section constitutes substantial improvement. If the work covered by this section is a structurally connected horizontal addition that does not constitute substantial improvement, the addition is 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 any nonconformity of the existing building 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 the lowest floor elevation required in Section 1612 of the International Building Code or Section R306 of the International Residential Code, as applicable.
SECTION 1304—INVESTIGATION AND EVALUATION
CEBC § 601.1.1 High relevance — show source text
601.1.1 Compliance with other alternatives. Alterations, additions and changes of occupancy to existing structures shall comply with the provisions of Chapters 7 through 11 or with one of the alternatives provided in Section 301.3.
601.2 Work area. The work area, as defined in Chapter 2, shall be identified on the construction documents.
SECTION 602—ALTERATION—LEVEL 1
602.1 Scope. Level 1 alterations include the removal and replacement or the covering of existing materials, elements, equipment or fixtures using new materials, elements, equipment or fixtures that serve the same purpose.
602.2 Application. Level 1 alterations shall comply with the provisions of Chapter 7.
SECTION 603—ALTERATION—LEVEL 2
603.1 Scope. Level 2 alterations include the addition or elimination of any door or window, the reconfiguration or extension of any system, or the installation of any additional equipment, and shall apply where the work area is equal to or less than 50 percent of the building area.
Exception: The movement or addition of nonfixed and movable fixtures, cases, racks, counters and partitions not over 5 feet 9 inches (1753 mm) in height shall not be considered a Level 2 alteration.
603.2 Application. Level 2 alterations shall comply with the provisions of Chapter 7 for Level 1 alterations as well as the provisions of Chapter 8.
SECTION 604—ALTERATION—LEVEL 3
604.1 Scope. Level 3 alterations apply where the work area exceeds 50 percent of the building area.
604.2 Application. Level 3 alterations shall comply with the provisions of Chapters 7 and 8 for Level 1 and 2 alterations, respectively, as well as the provisions of Chapter 9.
SECTION 605—CHANGE OF OCCUPANCY
605.1 Scope. Change of occupancy provisions apply where the activity is classified as a change of occupancy as defined in Chapter 2.
605.2 Application. Changes of occupancy shall comply with the provisions of Chapter 10.
SECTION 606—ADDITIONS
606.1 Scope. Provisions for additions shall apply where work is classified as an addition as defined in Chapter 2.
606.2 Application. Additions to existing buildings shall comply with the provisions of Chapter 11.
SECTION 607—HISTORIC BUILDINGS
607.1 Scope. The provisions of the California Historical Building Code (Part 8, Title 24, C.C.R) shall apply to qualified historical buildings or properties.
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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE
CHAPTER 7 – ALTERATIONS—LEVEL 1
(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CEBC § 1101.5 High relevance — show source text
1|||X|||||||||||||||||||||| |1101.5|||X|†|†|||||||||||||||||||| |1101.6||||†|†|||||||||||||||||||| |1102.2|||X|||||||||||||||||||||| |1102.3 Exception||||†|†|||||||||||||||||||| |1102.4|||X||||||||||||||||||||||
The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
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11 ADDITIONS
User notes:
About this chapter: Chapter 11 provides the requirements for additions, which correlate to the code requirements for new construction. There are, however, some exceptions that are specifically stated within this chapter. An “Addition” is defined in Chapter 2 as “an extension or increase in the floor area, number of stories or height of a building or structure.” Chapter 11 contains the minimum requirements for an addition that is not separated from the existing building by a fire wall.
SECTION 1101—GENERAL
1101.1 Scope. An addition to a building or structure shall comply with the California Building Standards Codes as adopted for new construction without requiring the existing building or structure to comply with any requirements of those codes or of these provisions, except as required by this chapter. Where an addition or alteration impacts the existing building or structure, the result of the addition or alteration shall not put the existing building or structure out of compliance with the California Building or Residential Code as applicable. The provisions of height and area of the California Building or Residential Code shall apply to the entire existing building with the additions.
1101.2 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] 1101.3 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 Chapter 10 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.
CEBC § 3.4 High 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 § 1.2. High relevance — show source text
1.2. If the addition constitutes substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.3. If the addition does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply: 1.3.1. The addition shall not create or extend any nonconformity of the existing building with the flood-resistant construction requirements. 1.3.2. The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or the lowest floor elevation required in Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 2. For horizontal additions that are not structurally interconnected to the existing building: 2.1. The addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Resi- dential Code, as applicable. 2.2. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 3. For vertical additions and all other proposed work that, when combined, constitute substantial improvement, the existing building shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 4. For a new foundation, replacement foundation or a foundation raised or extended upward, the foundation shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
SECTION 1104—ENERGY CONSERVATION
1104.1 Minimum requirements. Additions to existing buildings shall comply with applicable provisions of the California Energy Code (Part 6, Title 24, C.C.R).
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12 HISTORIC BUILDINGS
Chapter 12 is not adopted by the State of California.
Historic buildings and structures shall comply with Part 8, Title 24, California Code of Regulations.
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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE
CHAPTER 13 – PERFORMANCE COMPLIANCE METHODS
Not adopted by the State of California (May be available for adoption by local ordinance. See Section 1.1.11.) (See Section 104.11 for consideration of alternative means of compliance.)
CEBC § 301.1.1 High relevance — show source text
1||||X||||X||||||||||||||| |301.1.1||||X||||||||||||||||||| |301.2||||X||||||||||||||||||| |301.3||X||||||||||||||||||||| |301.3.1||X||||||||||||||||||||| |301.3.2||X||||||||||||||||||||| |301.4||||||||X||||||||||||||| |301.5|||||||||X||X||X|||||||||| |302||X||X||||X|X||X||X|||||||||| |303||X||X|||||X||X||X|||||||||| |303.1||X||||||||||||||||||||| |304||X||X|||||X||X||X|||||||||| |305|||||||||X|||||||||||||| |306||||||||X|||||||||||||||
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3 GREEN BUILDING
SECTION 301—GENERAL
301.1 Scope. Buildings shall be designed to include the green building measures specified as mandatory in the application checklists contained in this code. Voluntary green building measures are also included in the application checklists and may be included in the design and construction of structures covered by this code, but are not required unless adopted by a city, county, or city and county as specified in Section 101.7.
301.1.1 Additions and alterations. [HCD] The mandatory provisions of Chapter 4 shall be applied to additions or alterations of existing residential buildings where the addition or alteration increases the building’s conditioned area, volume or size. The requirements shall apply only to and/or within the specific area of the addition or alteration.
The mandatory provisions of Section 4.106.4.2 may apply to additions or alterations of existing parking facilities or the addition of new parking facilities serving existing multifamily buildings. See Section 4.106.4.3 for application.
Note: Repairs including, but not limited to, resurfacing, restriping, and repairing or maintaining existing lighting fixtures are not considered alterations for the purpose of this section.
301.2 Low-rise and high-rise residential buildings. [HCD] The provisions of individual sections of CALGreen may apply to either low-rise residential buildings, high-rise residential buildings, or both. Individual sections will be designated by banners to indicate where the section applies specifically to low-rise only (LR) or high-rise only (HR). When the section applies to both low-rise and highrise buildings, no banner will be used.
301.3 Nonresidential additions and alterations. [BSC-CG] The provisions of individual sections of Chapter 5 apply to newly constructed buildings, building additions of 1,000 square feet or greater, and/or building alterations with a permit valuation of $200,000 or above (for occupancies within the authority of California Building Standards Commission). Code sections relevant to additions and alterations shall only apply to the portions of the building being added or altered within the scope of the permitted work.
A code section will be designated by a banner to indicate where the code section only applies to newly constructed buildings [N] or to additions and/or alterations [A] . When the code section applies to both, no banner will be used.
CEBC § 304.3.1 High relevance — show source text
Exceptions:
- 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 comply with the conventional light-frame construction methods of the Cali- fornia Building Code or the provisions of the California Residential Code .
- 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 Section 1609 of the California Building Code and Section 304.3.1 of this 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 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 304.3.1 or the full seismic forces in effect at the time.
[BS] 1103.3 Flood hazard areas. Additions and foundations in flood hazard areas shall comply with the following requirements:
- For horizontal additions that are structurally interconnected to the existing building: 1.1. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.2. If the addition constitutes substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.3. If the addition does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply: 1.3.1. The addition shall not create or extend any nonconformity of the existing building with the flood-resistant construction requirements. 1.3.2. The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or the lowest floor elevation required in Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
- For horizontal additions that are not structurally interconnected to the existing building: 2.1. The addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Resi- dential Code, as applicable. 2.2. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
- For vertical additions and all other proposed work that, when combined, constitute substantial improvement, the existing building shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
CEBC § 4.106.4.2 High relevance — show source text
The mandatory provisions of Section 4.106.4.2 may apply to additions or alterations of existing parking facilities or the addition of new parking facilities serving existing multifamily buildings. See Section 4.106.4.3 for application.
Note: Repairs including, but not limited to, resurfacing, restriping, and repairing or maintaining existing lighting fixtures are not considered alterations for the purpose of this section.
301.2 Low-rise and high-rise residential buildings. [HCD] The provisions of individual sections of CALGreen may apply to either low-rise residential buildings, high-rise residential buildings, or both. Individual sections will be designated by banners to indicate where the section applies specifically to low-rise only (LR) or high-rise only (HR). When the section applies to both low-rise and highrise buildings, no banner will be used.
301.3 Nonresidential additions and alterations. [BSC-CG] The provisions of individual sections of Chapter 5 apply to newly constructed buildings, building additions of 1,000 square feet or greater, and/or building alterations with a permit valuation of $200,000 or above (for occupancies within the authority of California Building Standards Commission). Code sections relevant to additions and alterations shall only apply to the portions of the building being added or altered within the scope of the permitted work.
A code section will be designated by a banner to indicate where the code section only applies to newly constructed buildings [N] or to additions and/or alterations [A] . When the code section applies to both, no banner will be used.
301.3.1 Nonresidential additions and alterations that cause updates to plumbing fixtures only:
Note: On and after January 1, 2014, certain commercial real property, as defined in Civil Code Section 1101.3, shall have its noncompliant plumbing fixtures replaced with appropriate water-conserving plumbing fixtures under specific circumstances. See Civil Code Section 1101.1 et seq. for definitions, types of commercial real property affected, effective dates, circumstances necessitating replacement of noncompliant plumbing fixtures, and duties and responsibilities for ensuring compliance.
301.3.2 Waste diversion. The requirements of Section 5.408 shall be required for additions and alterations whenever a permit is required for work.
301.4 Mandatory measures for public schools and community colleges. [DSA-SS] New building construction and site work on a new or existing site shall comply with Section 301.4.
301.4.1 Building and site construction on a new site shall comply with Chapter 5 as adopted by DSA-SS.
301.4.2 Work on an existing site shall comply with Section 301.4.2.
301.4.2.1 Newly constructed site work shall comply with Chapter 5 as adopted by DSA-SS.
301.4.2.2 Newly constructed buildings shall comply with Chapter 5 as adopted by DSA-SS and Section 301.4.3.
301.4.2.3 Additions to existing buildings shall comply with Section 301.4.3.
301.4.2.4 Rehabilitated landscape areas shall comply with Sections 5.304.6 and 5.106.12.
301.4.2.5 Alterations and additions to existing parking facilities shall comply with Section 5.106.5.6.4. Additions to existing parking facilities shall comply with Section 5.106.12.
CEBC § 7.12 High relevance — show source text
SECTION 303 A — RESERVED
SECTION 304 A —STRUCTURAL DESIGN LOADS AND EVALUATION AND DESIGN PROCEDURES
304 A .1 Live loads. Where an addition or alteration does not result in increased design live load, existing gravity load-carrying structural elements shall be permitted to be evaluated and designed for live loads approved prior to the addition or alteration. If the approved live load is less than that required by Section 1607 A of the California Building Code, the area designated for the nonconforming live load shall be posted with placards of approved design indicating the approved live load. Where the addition or alteration results in increased design live load, the live load required by Section 1607 A of the California Building Code shall be used.
304 A .2 Snow loads on adjacent buildings. Where an alteration or addition changes the potential snow drift effects on an adjacent building, the code official is authorized to enforce Section 7.12 of ASCE 7.
304 A .3 Additions, alterations, repairs and seismic retrofit to existing buildings or structures.
304 A .3.1 Structures designed in accordance with pre-1973 building code. Provisions of this section shall apply to hospital build- ings which were originally designed to pre-1973 building codes and not designated as SPC 3 or higher in accordance with Chapter 6 of the California Administrative Code.
304A.3.1.1 Incidental and minor structural alteration, additions, or repairs. Incidental and minor structural additions shall be permitted, provided the additions meet the California Building Code for new construction using importance factor, I e , equal to or greater than 1.0. Alterations or repair to existing gravity and lateral force-resisting systems shall be made to conform to the requirements of Section 503A or Chapter 4A, respectively, using importance factor, I e , equal to or greater than 1.0. 1. Nonstructural components. Component importance factor, I p , shall be permitted to be 1.0.
Exception: Components required for life-safety purposes after an earthquake, including emergency and standby power systems, mechanical smoke removal systems, fire protection sprinkler systems, fire alarm control panels and egress stairways shall have a component importance factor (I p ) of 1.5.
304A.3.1.2 Major structural alteration, additions or repairs. Major structural alterations, additions or repairs shall be in accor- dance with Section 304A.3.4.1 or 304A.3.4.3 as applicable.
304A.3.2 Seismic evaluation and retrofit of general acute care hospitals for compliance with the California Administrative Code, Chapter 6. Notwithstanding any other requirements of this code, existing general acute care hospitals shall comply with the seismic evaluation requirements specified in Chapter 6, of the California Administrative Code, when applicable. Seismic retrofit to comply with requirements specified in Chapter 6 of the California Administrative Code shall be permitted to be in accordance with these provisions. When load combinations which do not include seismic forces are required, the new building provisions of this code shall be applicable.
CEBC § 170.1 High relevance — show source text
b. Either:
(i) Performance approach: Section 170.1; or (ii) Prescriptive approach: Section 170.2(a) through (f).
F. Covered processes.
i. Sections applicable. Sections 110.2, 120.3, 120.6, 140.9, and 141.1 apply to covered processes. ii. Compliance approaches. In order to comply with Part 6, covered processes must meet the requirements of: a. The applicable mandatory measures in Sections 110.2, 120.3 and 120.6; and
b. Either:
(i) The performance approach requirements of Section 140.1; or (ii) The prescriptive approach requirements of Section 140.9. 3. New construction in existing buildings (additions, alterations and repairs). A. Nonresidential and hotel/motel buildings. Section 141.0 applies to new construction in existing nonresidential, high-rise residential and hotel/motel buildings. New construction in existing buildings includes additions, alterations and repairs. Section 141.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specify which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 141.0 apply to the occupancy after the alterations. B. Single-family buildings. Section 150.2 applies to new construction in existing single-family buildings. New construction in existing buildings includes additions, alterations and repairs. Section 150.2 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specifies which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 150.2 apply to the occupancy after the alterations. C. Multifamily buildings. Section 180.0 applies to new construction in existing multifamily buildings. New construction in existing buildings includes additions, alterations and repairs. Section 180.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specifies which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 180.0 apply to the occupancy after the alterations. 4. Installation of insulation in existing buildings. Section 110.8(d) applies to buildings in which insulation is being installed in existing attics, or on existing water heaters or existing space conditioning ducts. 5. Outdoor lighting. Sections 110.9, 130.0, 130.2, 130.4, 140.7, and 150.0 apply to newly constructed outdoor lighting systems, and Section 141.0 applies to outdoor lighting that is either added or altered. 6. Signs. Sections 130.0, 130.3 and 140.8 apply to newly constructed signs located either indoors or outdoors, and Section 141.0 applies to sign alterations located either indoors or outdoors.
2025 CALIFORNIA ENERGY CODE 3
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ALL OCCUPANCIES—GENERAL PROVISIONS
(f) Mixed occupancy. When a building is designed and constructed for more than one type of occupancy (residential and nonresidential), the space for each occupancy shall meet the provisions of Part 6 applicable to that occupancy.
Frequently asked questions
When is work classified as an “addition” under the CEBC?
An addition increases the floor or roof area, number of stories, or height and is structurally attached to the existing building. If it meets that definition, CEBC addition provisions apply.
Do additions always force the entire existing building to meet brand-new building code requirements?
No. The CEBC requires the addition itself to comply with new-construction provisions (IBC/IRC), but it does not automatically require every unrelated aspect of the existing building to be rebuilt to new-construction standards — except where the addition creates impacts (risk category change, flood substantial improvement, or other specified triggers). See § 1101.1 and § 1302.1.3.
If my addition makes the combined building exceed IBC Chapter 5 limits, what are my options?
You may reduce the addition, change construction/occupancy type as allowed, or provide an IBC §706-compliant firewall between the addition and existing building so the addition is treated as a separate building (then Chapter 5 limits apply separately). § 1302.1.3 explains this.
Does adding a new occupiable roof have special requirements?
Yes — the CEBC requires any new occupiable roof be made to comply with the provisions of the IBC for such roofs; that requirement is in § 1302.1.3.
How do flood hazard rules affect additions?
If the addition constitutes a substantial improvement in a mapped flood hazard area, flood-design requirements for new construction apply to the addition and often to the existing structure as described in CEBC flood provisions (see § 1303.1.3 and related text). There are narrowly defined exceptions for some non-substantial additions — check the CEBC text for conditions.
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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California Existing Building Code