CEBC · California Existing Building Code

When does adding to a building change its risk category or trigger change-of-occupancy requirements?

If your addition and the existing building have different occupancies, the CEBC requires you to determine Risk Categories per the California Building Code; if that process raises the existing building’s Risk Category it’s treated as a change of occupancy (Chapter 10 rules apply), and if the addition itself is assigned a higher Risk Category the addition and any existing systems serving it must be built to the higher new‑construction standard (CEBC § 1101.3).

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The California Existing Building Code (CEBC) says that when an addition and the existing building have different occupancies you must determine the Risk Category of each per the California Building Code (CBC) § 1604.5.1. If that determination raises the Risk Category of the existing building above what it was before the addition, the project is treated as a change of occupancy and must comply with the CEBC change‑of‑occupancy requirements (Chapter 10). If the addition itself is assigned a higher Risk Category than it would be standing alone, the addition — and any building systems of the existing building required to serve it — must meet the CBC requirements for new construction for the higher Risk Category. § 1101.3

Plain English: if adding new space (or a different use) makes the building “riskier” than it was before, the CEBC treats the work as a change of occupancy or requires the addition to be built to the higher (new‑construction) risk standard. § 1101.3

Requirements in detail

Key defined terms (first use bolded)

Addition — an extension or increase in floor area, number of stories or height of a building (defined in Chapter 2; CEBC directs Chapter 11 for additions).
Risk Category — assignment per CBC § 1604.5.1, used to determine seismic, wind, snow, and other design criteria (CEBC references that CBC section for the assignment). § 1101.3
Change of occupancy — when application of the risk‑category assignment causes the existing building to be elevated to a higher Risk Category; triggers Chapter 10 CEBC requirements. § 1101.3

Decision matrix — what to check, what happens

Decision dimension	Values / thresholds to evaluate	Outcome under CEBC	Code reference
Do the addition and existing building have different occupancies?	Yes / No	If No, normal addition rules apply. If Yes, determine Risk Category per CBC § 1604.5.1.	§ 1101.3
Does applying CBC § 1604.5.1 raise the Risk Category of the existing building compared with its pre‑addition assignment?	Higher / Not higher	If Higher → treated as a change of occupancy; comply with CEBC Chapter 10 (change‑of‑occupancy provisions).	§ 1101.3
Does applying CBC § 1604.5.1 assign a higher Risk Category to the addition than it would have by itself?	Higher / Not higher	If Higher → the addition and any existing building systems required to serve it must comply with CBC new‑construction requirements for that higher Risk Category.	§ 1101.3
Is the new occupancy area small relative to the building (exception)?	Area of new occupancy < 10% of building area	Some structural/wind/snow (and other) upgrade triggers when building is reassigned to a higher Risk Category are not required where the new occupancy area is < 10% (cumulative changes considered).	§ 506.5.2
Does the addition increase gravity loads on existing members by more than 5%?	≤ 5% / > 5%	If > 5% increase in dead/live/snow tributary loads → affected existing gravity‑load members must be replaced or altered to meet CBC new‑construction gravity requirements.	§ 502.3

Notes:

The CEBC explicitly defers the actual Risk Category assignment procedure to the CBC § 1604.5.1; CEBC uses that CBC outcome to determine whether a change of occupancy has occurred or whether the addition must be designed to the higher category. § 1101.3
When the CEBC calls for compliance with the CBC for new construction, follow the CBC clauses (e.g., on structural, fire‑protection, means of egress) for that Risk Category; the CEBC itself does not restate those CBC design rules. § 1101.3

Exceptions & special cases

Small‑area exception: When a change of occupancy would result in higher Risk Category, some structural load‑ and environmental‑load upgrades required by that reclassification are not required if the area of the new occupancy is less than 10 percent of the building area; however the CEBC requires considering cumulative occupancy changes over time. § 506.5.2
Nonconforming nonstructural supports: Nonconforming supports for nonstructural components that serve the addition from within the existing building need not be altered to meet CBC § 1613 unless they are part of the addition’s life‑safety system or required to serve an addition assigned to Risk Category IV. § 1101.2 (exception)
Flood hazard areas: Additions that are "substantial improvements" in flood hazard areas must bring the entire existing structure into compliance with CBC flood design new‑construction requirements; smaller additions may be allowed if they do not create or extend a nonconformity and meet lowest‑floor elevation tests. § 502.A.2

Common mistakes

Assuming occupancy change only means tenant change: CEBC focuses on whether the Risk Category (per CBC § 1604.5.1) of the existing building increases after the addition, not merely if a different tenant moves in. The risk‑category outcome (not the label of the occupancy alone) controls whether Chapter 10 applies. § 1101.3
Forgetting system‑wide effects: If the addition’s Risk Category is higher for the addition itself, the CEBC requires that any existing building systems required to serve the addition comply with the higher‑category CBC new‑construction rules — not just the new footprint. § 1101.3
Ignoring the 5% gravity‑load rule: Small increases in gravity loads (≤ 5%) on existing elements may be permitted without full replacement; > 5% triggers replacement/alteration. § 502.3
Overlooking cumulative area exceptions: The <10% area exception for certain compliance requirements is cumulative — previous small changes can add up and remove the exception. § 506.5.2

Worked example — applying the rule with numbers

Scenario: An existing office building (current Risk Category II for the building as a whole) will receive a 3,000 ft² addition that contains assembly seating that would independently be assigned Risk Category III by CBC § 1604.5.1.

Step 1 — Determine risk categories per CBC § 1604.5.1 for the combined building (CEBC requires you to use the CBC procedure). The CEBC points you to CBC § 1604.5.1 for this determination; that CBC text is not reproduced here but is the required reference. § 1101.3

Step 2 — Compare the building’s prior Risk Category (II) with the combined result:

If the combined determination raises the building to Risk Category III (i.e., higher than II), the CEBC treats that as a change of occupancy and the project must comply with CEBC Chapter 10 (change of occupancy) and applicable CBC new‑construction requirements for Risk Category III (e.g., higher seismic/wind design, upgraded systems as required by Chapter 10). § 1101.3

Step 3 — If the addition itself, standing alone, is assigned Risk Category III (higher than what the addition alone would have been), the CEBC requires the addition and any existing building systems that must serve it to comply with CBC new‑construction rules for Risk Category III — even if the existing building's overall category does not change. § 1101.3

Step 4 — Check exceptions:

If the assembly area is less than 10% of building area, some of the structural/environmental upgrades tied to a higher Risk Category may not be required (see CEBC § 506.5.2), but cumulative changes count. § 506.5.2
If the addition increases gravity loads tributary to certain existing members by > 5%, those members must be upgraded per § 502.3.

(Important: the numeric Risk Category assignment procedure itself is in the CBC § 1604.5.1, referenced by CEBC § 1101.3; the CBC text must be consulted to classify occupancies into Risk Categories.)

Related provisions (CEBC sections)

§ 1101.1 — Scope for additions and relationship to CBC new‑construction provisions.
§ 1101.2 — Creation or extension of nonconformity; exception for certain nonstructural supports.
§ 1102.1 / § 1102.2 — Height and area limitations for additions (ties to CBC Chapter 5).
§ 502.1.1 — Risk category assignment for additions in the prescriptive compliance method (parallel language to § 1101.3).
§ 502.3 — Existing gravity load carrying elements: > 5% increase triggers replacement/alteration.
§ 506 (Chapter 10 provisions summarized) — Change of occupancy requirements and structural/loads/seismic consequences (includes the < 10% exception). See § 506.5.2 and related subsections.

Code references

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

CEBC § 501A.3.3.3 High relevance — show source text
501A.3.3.3 For NPC 3 and NPC 4 or NPC 4D in SPC 2, SPC 3, SPC 4 or SPC-4D buildings, the adequacy and design of nonstructural component or equipment supports and attachments may extend only to the connection of the component or equipment to the support when the total reaction at the point of support (including the application of F p ) is less than or equal to the following limits: 1. 250 pounds for components or equipment attached to light frame walls. For the purposes of this requirement, the sum of the absolute value of all reactions due to component loads on a single stud shall not exceed 250 pounds. 2. 1,000 pounds for components or equipment attached to roofs or walls of reinforced concrete or masonry construction. 3. 2,000 pounds for components or equipment attached to floors or slabs-on-grade.

Exception: If the anchorage or bracing is configured in a manner that results in significant torsion on a supporting structural element, the effects of the nonstructural reaction force on the structural element shall be considered in the anchorage design.

501 A . 4 Health care facilities. In Group I-2 facilities, ambulatory care facilities and outpatient clinics, any altered or added portion of an existing electrical or medical gas systems shall be required to meet installation and equipment requirements in NFPA 99.

SECTION 502 A —ADDITIONS

502 A .1 General. Additions to any building or structure shall comply with the requirements of the California Building Code for new construction. Alterations to the existing building or structure shall be made to ensure that the existing building or structure together with the addition are not less complying with the provisions of the California Building Code than the existing building or structure was prior to the addition. An existing building together with its additions shall comply with the height and area provisions of Chapter 5 of the California Building Code . Where a new occupiable roof is added to a building or structure, the occupiable roof shall comply with the provisions of the California 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 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.
CEBC § 915.1.2 High relevance — show source text
Exceptions: 1. The alteration replaces an existing fossil-fuel burning appliance, fireplace or forced-air furnace, or any of the conditions identified in Sections 915.1.2 through 915.1.6 are already present. 2. The Group E building was constructed before the adoption of the 2016 California Building Standards Code.

SECTION 502—ADDITIONS

502.1 General. Additions to any building or structure shall comply with the requirements of the California Building Code or California Residential Code, as applicable, for new construction. Alterations to the existing building or structure shall be made to ensure that

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PRESCRIPTIVE COMPLIANCE METHOD

the existing building or structure together with the addition are not less complying with the provisions of the California Building Code than the existing building or structure was prior to the addition except that the structural elements need only comply with Sections 502.2 through 502.3 . An existing building together with its additions shall comply with the height and area provisions of Chapter 5 of the California Building Code . Where a new occupiable roof is added to a building or structure, the occupiable roof shall comply with the provisions of the California Building Code. [OSHPD 1R, 2, 4 & 5] Structural elements shall comply with all the provisions of Section 502.

Exception s : 1. 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. 2. [BSC] For state-owned buildings, including those owned by the University of California and the California State University and the Judicial Council, structural elements shall also comply with the requirements of Sections 317 through 322.

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.
CEBC § 2.1. High relevance — show source text
1. A replacement window where such window complies with both of the following: 2.1. The replacement window meets the size requirements in Item 1. 2.2. The replacement window is the manufacturer’s largest standard size window that will fit within the existing frame or existing rough opening. The replacement window shall be permitted to be of the same operating style as the existing window or a style that provides for an equal or greater window opening area than the existing window.
506 A .5 Structural. Any building undergoing a change of occupancy shall satisfy the requirements of this section.

506 A .5.1 Live loads. Structural elements carrying tributary live loads from an area with a change of occupancy shall satisfy the requirements of Section 1607 A of the California Building Code . Design live loads for areas of new occupancy shall be based on Section 1607 A of the California Building Code . Design live loads for other areas shall be permitted to use previously approved design live loads.

Exception: Structural elements whose demand-capacity ratio considering the change of occupancy is not more than 5 percent greater than the demand-capacity ratio based on previously approved live loads need not comply with this section.

506 A .5.2 Snow and wind loads. Where a change of occupancy results in a structure being assigned to a higher risk category, the structure shall satisfy the requirements of Sections 1608 A and 1609 A of the California Building Code for the new risk category.

Exception: Where the area of the new occupancy is less than 10 percent of the building area, compliance with this section is not required. The cumulative effect of occupancy changes over time shall be considered.

506 A .5.3 Seismic loads (seismic force-resisting system). Where a change of occupancy results in a building being assigned to a higher risk category, the lateral force-resisting system of the building shall comply with the California Building Code Section 1613A or Section 304A.3.4 of this code for the new risk category. Where a change of occupancy results in a building being assigned to Risk Category IV and Seismic Design Category D or F, nonstructural components serving any portion of the building changed to Risk Category IV shall comply with the requirements of Section 1613 A of the California Building Code or shall comply with ASCE 41 -23 using an objective of Operational nonstructural performance with the BSE-1N earthquake hazard level.

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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

CHAPTER 6 – CLASSIFICATION OF WORK

(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 § 1.1 High 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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PRESCRIPTIVE COMPLIANCE METHOD

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:
1. The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
2. 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 § 1101.2 High relevance — show source text
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.

1101.4 Other work. Any repair or alteration work within an existing building to which an addition is being made shall comply with the applicable requirements for the work as classified in Chapter 6.

1101.5 Smoke barriers in Group R-2.1 . Where an addition to an existing Group R-2.1 building adds sleeping areas that result in more than 50 care recipients on a story, smoke barriers shall be provided to subdivide such story into not fewer than two smoke compartments in accordance with Section 420.6 of the California Building Code .

Exception: Where the existing building is divided into smoke compartments and the addition does not result in any individual smoke compartment exceeding the size and travel distance requirements in Section 420.6 of the California Building Code, additional smoke barriers are not required.

1101.6 Enhanced classroom acoustics. In Group E occupancies, enhanced classroom acoustics shall be provided in all classrooms in the addition with a volume of 20,000 cubic feet (565 m [3] ) or less. Enhanced classroom acoustics shall comply with the reverberation time in Section 808 of ICC A117.1.

1101.7 Occupiable roofs. Where a new occupiable roof is added to a building or structure, the occupiable roof shall comply with the provisions of the California Building Code .

SECTION 1102—HEIGHTS AND AREAS

1102.1 Height limitations. An addition shall not increase the height of an existing building beyond that permitted under the applicable provisions of Chapter 5 of the California Building Code for new buildings.

1102.2 Area limitations. An addition shall not increase the area of an existing building beyond that permitted under the applicable provisions of Chapter 5 of the California Building Code for new buildings unless fire separation as required by the California Building Code is provided.

1102.3 Fire protection systems. Existing fire areas increased by the addition shall comply with Chapter 9 of the California Building Code .
CEBC § 502.1.1 High 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:
1. The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
2. 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 § 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 § 506.2 High relevance — show source text
506.2 Certificate of occupancy. A certificate of occupancy shall be issued where it has been determined that the requirements for the new occupancy classification have been met.

506.3 Stairways. An existing stairway shall not be required to comply with the requirements of Section 1011 of the California Build- ing Code where the existing space and construction does not allow a reduction in pitch or slope.

506.4 Existing emergency escape and rescue openings. Where a change of occupancy would require an emergency escape and rescue opening in accordance with Section 1031.1 of the California Building Code, operable windows serving as the emergency escape and rescue opening shall comply with the following:
1. An existing operable window shall provide a minimum net clear opening of 4 square feet (0.38 m [2] ) with a minimum net clear opening height of 22 inches (559 mm) and a minimum net clear opening width of 20 inches (508 mm).
2. A replacement window where such window complies with both of the following: 2.1. The replacement window meets the size requirements in Item 1. 2.2. The replacement window is the manufacturer’s largest standard size window that will fit within the existing frame or existing rough opening. The replacement window shall be permitted to be of the same operating style as the existing window or a style that provides for an equal or greater window opening area than the existing window.
[BS] 506.5 Structural. Any building undergoing a change of occupancy shall satisfy the requirements of this section.

Exception: [BSC] For state-owned buildings, including those owned by the University of California and the California State University and the Judicial Council, the performance level requirements of Section 506.5 are replaced with the performance level requirements of Section 317.5.

[BS] 506.5.1 Live loads. Structural elements carrying tributary live loads from an area with a change of occupancy shall satisfy the requirements of Section 1607 of the California Building Code . Design live loads for areas of new occupancy shall be based on Section 1607 of the California Building Code . Design live loads for other areas shall be permitted to use previously approved design live loads.

Exception: Structural elements whose demand-capacity ratio considering the change of occupancy is not more than 5 percent greater than the demand-capacity ratio based on previously approved live loads need not comply with this section.

[BS] 506.5.2 Snow and wind loads. Where a change of occupancy results in a structure being assigned to a higher risk category, the structure shall satisfy the requirements of Sections 1608 and 1609 of the California Building Code for the new risk category.

Exception: Where the area of the new occupancy is less than 10 percent of the building area, compliance with this section is not required. The cumulative effect of occupancy changes over time shall be considered.

[BS] 506.5.3 Seismic loads (seismic force-resisting system). Where a change of occupancy results in a building being assigned to a higher risk category, or where the change is from a Group S or Group U occupancy to any occupancy other than Group S or

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CEBC § 5.3 High relevance — show source text

Exception: Where the area of the new occupancy is less than 10 percent of the building area, compliance with this section is not required. The cumulative effect of occupancy changes over time shall be considered.

506 A .5.3 Seismic loads (seismic force-resisting system). Where a change of occupancy results in a building being assigned to a higher risk category, the lateral force-resisting system of the building shall comply with the California Building Code Section 1613A or Section 304A.3.4 of this code for the new risk category. Where a change of occupancy results in a building being assigned to Risk Category IV and Seismic Design Category D or F, nonstructural components serving any portion of the building changed to Risk Category IV shall comply with the requirements of Section 1613 A of the California Building Code or shall comply with ASCE 41 -23 using an objective of Operational nonstructural performance with the BSE-1N earthquake hazard level.

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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

CHAPTER 6 – CLASSIFICATION OF WORK

(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- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
Adopting Agency	BSC	BSC- CG	SFM	1	2	1/AC	AC	SS	SS/CC	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
Adopt Entire Chapter				X	X
Adopt Entire Chapter as amended (amended sections listed below)			X
Adopt only those sections that are listed below
Chapter / Section
601.1			X
601.1.1			X
607.1			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.

CEBC § 2.1 Medium relevance — show source text
SECTION 302 A —GENERAL PROVISIONS

302 A .1 Dangerous conditions. The code official shall have the authority to require the elimination of conditions deemed dangerous.

302 A .2 Additional codes. Alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and struc- tures shall comply with the provisions for alterations, repairs, additions and changes of occupancy or relocation, respectively, in the California Fire Code, California Mechanical Code, California Plumbing Code and California Electrical Code. Where provisions of the other codes conflict with provisions of this chapter, the provisions of this chapter shall take precedence.

302 A .2.1 Additional codes in health care. In existing Group I-2 occupancies, ambulatory health care facilities, outpatient clinics and hyperbaric facilities, alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall also comply with NFPA 99.

302 A .3 Existing materials and equipment. Materials and equipment already in use in a building in compliance with requirements or approvals in effect at the time of their erection or installation shall be permitted to remain in use unless determined by the code official to be unsafe in accordance with California Building Code Section 116.

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PROVISIONS FOR ALL COMPLIANCE METHODS

302A.3.1 Existing seismic force-resisting systems. Where the existing seismic force-resisting system is a type that can be designated ordinary or is a welded steel moment frame constructed under a permit issued prior to October 25, 1994, values of R, W0 and Cd for the existing seismic force-resisting system shall be those specified by the California Building Code for an ordinary system unless it is demonstrated that the existing system will provide performance equivalent to that of a detailed, intermediate or special system.

302 A .4 New and replacement materials. Except as otherwise required or permitted by this code, materials and equipment permitted by the applicable code for new construction shall be used. Like materials shall be permitted for repairs and alterations, provided no hazard to life, health or property is c reated. Hazardous materials shall not be used where the code for new construction would not permit their use in buildings of similar occupancy, purpose and location.

302 A .4.1 New structural members and connections. New structural members and connections shall comply with the detailing provisions of the California Building Code for new buildings of similar structure, purpose and location.

Exception: Where alternative design criteria are specifically permitted.

302 A .5 Occupancy and use. Where determining the appropriate application of the referenced sections of this code, the occupancy and use of a building shall be determined in accordance with Chapter 3 of the California Building Code .
CEBC § 109.3.11 Medium relevance — show source text
3 – 109.3.11||||X|X|||||||||||||||||||| |109.3.6|X||X|||||X|X|||||||||||||||| |109.3.7|||X|||||||||||||||||||||| |110|||X|||||||||||||||||||||| |111|||X|||||||||||||||||||||| |113|||X|||||||||||||||||||||| |114|||X|||||||||||||||||||||| |115|||X|||||||||||||||||||||| |116.1|||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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1 ADMINISTRATION

DIVISION I CALIFORNIA ADMINISTRATION

SECTION 1.1—GENERAL

1.1.1 Title. These regulations shall be known as the California Existing Building Code, may be cited as such and will be referred to herein as “this code.” The California Existing Building Code is Part 10 of thirteen parts of the official compilation and publication of the adoption, amendment and repeal of building regulations to the California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This part incorporates by adoption the 2024 International Existing Building Code of the International Code Council with necessary California amendments.

1.1.2 Purpose. The purpose of this code is to establish the minimum requirements to safeguard the public health, safety and general welfare through structural strength, means of egress facilities, stability, access to persons with disabilities, sanitation, adequate lighting and ventilation and energy conservation; safety to life and property from fire and other hazards attributed to the built environment; and to provide safety to firefighters and emergency responders during emergency operations.

1.1.3 Scope. The provisions of this code shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures throughout the State of California. [HCD 1 & 2] The provisions of this code shall apply to repair, alteration, change of occupancy, addition to and relocation of every existing building or structure or any appurtenances connected or attached to such buildings or structures throughout the State of California.

1.1.3.1 Nonstate-regulated buildings, structures and applications. Except as modified by local ordinance pursuant to Section 1.1.8, the following standards in the California Code of Regulations, Title 24, Parts 2, 2.5, 3, 4, 5, 6, 7, 9, 10 and 11 shall apply to all occupancies and applications not regulated by a state agency.
CEBC § 10-3 Medium relevance — show source text
1003 Building Elements and Materials . . . . . . . . . . . . . . . . 10-3

1004 Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

1005 Means of Egress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

1006 Structural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

1007 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

1008 Mechanical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

1009 Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

1010 Other Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5

1011 Change of Occupancy Classification . . . . . . . . . . . . . 10-5

CHAPTER 11 ADDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3

1101 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3

1102 Heights and Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3

1103 Structural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4

1104 Energy Conservation. . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4

CHAPTER 12 HISTORIC BUILDINGS . . . . . . . . . . . . . . . . . .12-1

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CHAPTER 13 PERFORMANCE COMPLIANCE METHODS. . 13-3

1301 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3

1302 Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3

1303 Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-4

Frequently asked questions

When exactly do I have to use CBC § 1604.5.1?

The CEBC requires using CBC § 1604.5.1 to assign Risk Categories when an addition and the existing building have different occupancies; CEBC § 1101.3 points you to that CBC section for the classification step. The CEBC uses the CBC outcome to decide whether a change of occupancy or higher‑category new‑construction requirements are triggered. § 1101.3

If the addition has a higher Risk Category but the existing building’s Risk Category doesn’t change, what must I do?

If the addition’s Risk Category is higher than the addition would have alone, the addition and any systems in the existing building required to serve the addition must comply with CBC new‑construction requirements for that higher Risk Category. § 1101.3

Does a small addition ever force the whole building to upgrade?

Possibly — if applying the CBC risk‑assignment raises the building’s Risk Category, CEBC treats that as a change of occupancy and Chapter 10 compliance is required. However, where the change affects less than 10% of the building area, some of the higher‑category structural/environmental requirements may not apply (CEBC § 506.5.2), remembering cumulative changes count.

What about structural members that pick up extra load because of the addition?

If an addition and its related alterations cause an increase in design dead, live or snow load on an existing gravity‑load member of more than 5%, that element must be replaced or altered to meet CBC new‑construction gravity requirements. § 502.3

Where can I find the CEBC rule that a Risk Category increase equals a change of occupancy?

See § 1101.3 of the CEBC — it explicitly states that if applying CBC § 1604.5.1 results in a higher Risk Category for the existing building, that is a change of occupancy and Chapter 10 applies. § 1101.3

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California Existing Building Code