CEBC · California Existing Building Code
Change of occupancy under the prescriptive method
You must evaluate any proposed change of occupancy against CEBC **§ 506**: the building must meet the CBC requirements for the new use and cannot be left less compliant; structural, egress, seismic and other upgrades depend on clear thresholds (notably **10%** area and **5%** demand‑capacity change), and special rules apply for emergency egress windows and Group E acoustics.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
A change of occupancy may not be made unless the building is made to comply with the requirements of the California Building Code for the new use, and the existing building is not left in a condition less complying than before the change (see § 506.1). Subject to the code official, a change may be permitted without meeting every new‑construction requirement when the new occupancy is less hazardous than the existing occupancy (see § 506) . For certain special topics (for example, enhanced classroom acoustics in Group E), the prescriptive chapter adds specific triggers and thresholds (see § 506.6) .
The single most important rule: you cannot simply switch an occupancy; the building must be evaluated and brought to at least the same level of code compliance it had before the change, and additional upgrades are required when the change increases hazards or exceeds listed thresholds (see § 506.1) .
Requirements in detail
Core compliance principle
- The baseline rule is in § 506.1: make the building comply with CBC requirements for the new use, and ensure the building is not made “less complying” than it was before the change. Where the new occupancy is less hazardous, the code official may allow limited departures from full new‑construction requirements .
Decision‑relevant dimensions and thresholds
| Decision dimension | Key value or trigger | What that requires | Code Reference |
|---|---|---|---|
| Minimum emergency escape opening (existing window) | 4 sq ft net clear; 22 in min height; 20 in min width | Existing operable windows used for emergency escape must meet these minimums or be replaced per the replacement‑window rules | § 506.4 |
| Replacement window sizing rule | Replacement must be the manufacturer’s largest standard size that fits the existing frame/rough opening | Replacement allowed of same or larger operating style if it meets the opening size | § 506.4 (2) |
| Structural live load upgrade | Default: design live loads per CBC § 1607 for areas of new occupancy | Structural elements carrying tributary live loads for the changed area shall satisfy CBC § 1607; previously approved live loads may be used elsewhere | § 506.5.1 |
| Small demand change exception | ≤ 5% increase in demand‑capacity ratio | No live‑load upgrade required where change in demand‑capacity ≤ 5% | § 506.5.1 Exception |
| Area threshold for structural/seismic exceptions | 10 percent of building area | If new occupancy area is less than 10%, some structural/seismic upgrade requirements do not apply (see individual exceptions) | § 506.5.2 / § 506.5.3 Exceptions |
| Seismic trigger | Change to a higher Risk Category or from Group S/U to other groups | Lateral force‑resisting system must comply with Section 304.3.1 for the new risk category (special rules when assigned to Risk Category IV and SDC D/F) | § 506.5.3 |
| Work‑area threshold for acoustics (Group E) | Work area exceeds 50 percent of building area | Provide enhanced classroom acoustics in classrooms ≤ 20,000 cu ft per § 808 of ICC A117.1 | § 506.6 |
| Certificate of occupancy | Issued when requirements for new occupancy classification have been met | Code official must determine compliance before issuing certificate | § 506.2 |
How code officials may limit scope
- The code official may allow limited compliance when the new occupancy is less hazardous (see § 506.1). That is an administrative, case‑by‑case allowance — plan approval and justification are required .
Structural and hazard reclassification
- Where the change produces a higher Risk Category or other hazard increase, the CEBC requires upgrades to live load, wind/snow, and seismic performance consistent with CBC chapters indicated in § 506.5 and its subsections. Exceptions exist for small area changes and certain seismic coefficient conditions — consult the specific text in § 506.5.1–506.5.4 .
Exceptions & special cases
- Exception for Chapter 16 (CBC): the building need not be made to comply with CBC Chapter 16 unless required by § 506.5 (structural triggers) — see § 506.1 Exception .
- Small area changes: If the new occupancy area is less than 10 percent of the building area, some structural, snow/wind and seismic requirements in § 506.5 do not apply (but the cumulative effect of changes over time must be considered) .
- Minor structural demand increase: If the demand‑capacity ratio for an element rises by no more than 5 percent, that element need not be upgraded for live load changes under § 506.5.1 Exception .
- Replacement windows for egress: replacement windows are permitted when they meet the stated opening size limits and are the largest standard size that fits the existing frame per § 506.4 .
- OSHPD/state‑regulated buildings: Chapter 5A contains analogous prescriptive provisions for state‑regulated health facilities; some sections are modified or replaced for those buildings (see Chapter 5A and related notes) .
Common mistakes
- Treating an administrative “less hazardous” determination as automatic. The code official’s approval is required before reduced compliance is allowed (see § 506.1) .
- Ignoring the 10 percent area threshold and cumulative changes over time — repeated small changes can trigger upgrades even if each single change was below 10% (see § 506.5 exceptions) .
- Forgetting the 5 percent demand‑capacity exception calculation; designers sometimes upgrade elements unnecessarily rather than checking the demand‑capacity change against § 506.5.1 .
- Overlooking emergency escape opening minimums when a change of occupancy would require an egress window — existing windows must meet the 4 sq ft / 22 in / 20 in minima or be replaced per § 506.4 .
- Missing special provisions that cross‑reference other codes (electrical, plumbing, fire protection): changes that create hazardous or special occupancies trigger applicable California Electrical/Plumbing/Fire Code requirements (see CEBC cross references and Chapter 10/1011 references) .
Worked example — concrete scenario
Scenario: A 3,000 ft² one‑story retail building (Group M) is proposed to be partially converted—1 tenant space of 500 ft² (≈ 16.7% of building area) will change to a small educational use (Group E). The work area (the changed space) includes classroom work that will occupy rooms ≤ 20,000 cu ft.
Step 1 — Area thresholds:
- Changed area = 500 ft² = 16.7% of 3,000 ft². Because this exceeds 10 percent, the structural and seismic upgrade triggers in § 506.5 apply (exceptions for <10% do not apply) .
Step 2 — Structural live load:
- For the area of new occupancy (Group E), design live loads must be based on CBC § 1607 per § 506.5.1. Evaluate tributary live loads on affected structural elements; if any element’s demand‑capacity ratio increases more than 5%, upgrade or reinforce that element; if ≤ 5%, the exception lets you avoid upgrade (see § 506.5.1 and its Exception) .
Step 3 — Seismic/wind/snow:
- Because the change results in no higher Risk Category (Group E from M likely remains same risk category depending on classification) but area >10%, check § 506.5.2/506.5.3: if the change assigns a higher Risk Category or moves from Group S/U, lateral system compliance per Section 304.3.1 is required; otherwise follow exception text. Verify risk category and S_DS limits in § 506.5.3 .
Step 4 — Enhanced acoustics:
- Work area exceeds 50 percent of building? No — the changed area is 16.7%, so § 506.6 enhanced classroom acoustics requirement does not apply. If instead the work area had been >50%, classrooms ≤ 20,000 cu ft would require enhanced acoustics per § 506.6 (see § 808 of ICC A117.1 for reverberation times) .
Step 5 — Egress / egress windows / certificate:
- If the educational use requires emergency escape openings where none existed, ensure operable windows meet 4 sq ft / 22 in / 20 in minimums per § 506.4, or provide compliant replacements; obtain Certificate of Occupancy only when the code official determines the new occupancy requirements are met (§ 506.2) .
Related provisions
- § 506 — Change of occupancy (general)
- § 506.1 — Compliance principle for change of occupancy (make building comply / no less complying)
- § 506.2 — Certificate of occupancy requirement after compliance is verified
- § 506.4 — Existing emergency escape and rescue openings (minimum opening dimensions and replacement rules)
- § 506.5 / 506.5.1–506.5.4 — Structural triggers: live loads, snow/wind, seismic, access to Risk Category IV and related exceptions
- § 506.6 — Enhanced classroom acoustics (Group E, work area >50%, rooms ≤20,000 cu ft)
- Chapter 5A — Prescriptive method modifications for state‑regulated health facilities (OSHPD) where applicable
- Chapter 10 (CEBC) / §§ 1001–1011 — Change of occupancy classification and related fire‑protection / egress requirements (cross‑references)
Code references
Grounded in the retrieved California Existing Building Code — click a citation to read the verbatim passage:
CEBC § 1011.5.6. High relevance — show source text
- 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.
- Where the replacement of the window is part of a change of occupancy, it shall comply with Section 1011.5.6.
505.3.1 Control devices. Window opening control devices or fall prevention devices complying with ASTM F2090 shall be permitted for use on windows required to provide emergency escape and rescue openings. After operation to release the control device allowing the window to fully open, the control device shall not reduce the net clear opening area of the window unit. Emergency escape and rescue openings shall be operational from the inside of the room without the use of keys or tools.
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505.4 Bars, grilles, covers or screens. Bars, grilles, covers, screens or similar devices are permitted to be placed over emergency escape and rescue openings, bulkhead enclosure or window wells that serve such openings, provided all of the following conditions are met:
- The minimum net clear opening size complies with the code that was in effect at the time of construction.
- Such devices shall be releasable or removable from the inside without the use of a key, tool or force greater than that which is required for normal operation of the escape and rescue opening.
- Where such devices are installed, they shall not reduce the net clear opening of the emergency escape and rescue openings .
- Smoke alarms shall be installed in accordance with Section 907.2.11 of the California Building Code .
SECTION 506—CHANGE OF OCCUPANCY
506.1 Compliance. A change of occupancy shall not be made in any building unless that building is made to comply with the requirements of the California Building Code for the use or occupancy. Changes of occupancy in a building or portion thereof shall be such that the existing building is not less complying with the provisions of this code than the existing building or structure was prior to the change. Subject to the approval of the code official, changes of occupancy shall be permitted without complying with all of the requirements of this code for the new occupancy, provided that the new occupancy is less hazardous, based on life and fire risk, than the existing occupancy.
Exception: The building need not be made to comply with Chapter 16 of the California Building Code unless required by Section 506.5.
506.1.1 Change in the character of use. A change of occupancy with no change of occupancy classification shall not be made to any structure that will subject the structure to any special provisions of the applicable California Codes, without approval of the code official. Compliance shall be only as necessary to meet the specific provisions and is not intended to require the entire building be brought into compliance.
506.1.2 Change in function. [OSHPD 1R, 2, 4 and 5] A change in function shall require compliance with all the functional require- ments for new construction in the California Building Code, including requirements in Sections 1224, 1225, 1226, 1227 and 1228.
CEBC § 506.1 High relevance — show source text
SECTION 506—CHANGE OF OCCUPANCY
506.1 Compliance. A change of occupancy shall not be made in any building unless that building is made to comply with the requirements of the California Building Code for the use or occupancy. Changes of occupancy in a building or portion thereof shall be such that the existing building is not less complying with the provisions of this code than the existing building or structure was prior to the change. Subject to the approval of the code official, changes of occupancy shall be permitted without complying with all of the requirements of this code for the new occupancy, provided that the new occupancy is less hazardous, based on life and fire risk, than the existing occupancy.
Exception: The building need not be made to comply with Chapter 16 of the California Building Code unless required by Section 506.5.
506.1.1 Change in the character of use. A change of occupancy with no change of occupancy classification shall not be made to any structure that will subject the structure to any special provisions of the applicable California Codes, without approval of the code official. Compliance shall be only as necessary to meet the specific provisions and is not intended to require the entire building be brought into compliance.
506.1.2 Change in function. [OSHPD 1R, 2, 4 and 5] A change in function shall require compliance with all the functional require- ments for new construction in the California Building Code, including requirements in Sections 1224, 1225, 1226, 1227 and 1228.
Exception [OSHPD 1R] : Hospital buildings removed from acute care service adapted for re-use as skilled nursing facilities, acute psychiatric hospitals or out-patient services of a hospital may be permitted to meet the minimum room clearances, areas and dimensions of the 2001 California Building Code for existing rooms re-used for a similar purpose, subject to the approval of OSHPD.
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:
- 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).
- 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.
CEBC § 1.10.1 High relevance — show source text
Chapter 5A Prescriptive Compliance Method.
Chapter 5A provides details for the prescriptive compliance method for alteration, addition and change of occupancy of existing build- ings and structures regulated by the Department of Health Care Access and Information/Office of Statewide Hospital Planning and Development, which include hospitals and correctional treatment centers (applications listed in Sections 1.10.1 (OSHPD 1).
Chapter 6 Classification of Work.
Chapter 6 provides an overview of the Work Area Method and defines the different classifications of work including alterations, change of occupancy, additions and historic buildings. Detailed requirements for all of these are given in subsequent Chapters 7 through 11.
Chapter 7 Alterations—Level 1.
Chapter 7 provides the technical requirements for those existing buildings that undergo Level 1 alterations as described in Section 602, which includes replacement or covering of existing materials, elements, equipment or fixtures using new materials for the same purpose. This chapter is distinguished from Chapters 8 and 9 by only involving replacement of building components with new components with no reconfiguration of space.
Chapter 8 Alterations—Level 2.
A Level 2 alteration is an alteration involving space reconfiguration that could be up to and including 50 percent of the area of the building or addition of a new building system. Level 2 alterations also include the extension or addition of any system or equipment. The purpose of Chapter 8 is to provide detailed requirements and provisions to identify the required improvements in the existing building elements, means of egress, fire protection, structural systems, energy efficiency, and other building systems include electrical, mechanical and plumbing when a building is being altered.
Chapter 9 Alterations—Level 3.
Chapter 9 provides the technical requirements for those existing buildings that undergo Level 3 alterations. Level 3 alterations are those involving alterations that cover 50 percent of the aggregate area of the building. Under certain situations, this chapter also intends to improve the safety of certain building features beyond the work area and in other parts of the building where no alteration work might be taking place.
Chapter 10 Change of Occupancy.
The purpose of Chapter 10 is to address existing buildings that are subject to a change of occupancy. This chapter is an assembly of requirements to upgrade safety without having to comply fully as a new building. A change of occupancy classification is considered a change of occupancy, however, it will involve a higher level of regulation since the use of the building has made a more significant change.
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Chapter 11 Additions.
Chapter 11 provides the requirements for additions, which are considered new construction. The requirements focus on safely integrating the addition with the existing building. This includes issues such as limiting the overall height and area of the building where the addition is not separated by a fire wall.
Chapter 12 Historic Buildings —Reserved
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.
Chapter 13 Performance Compliance Methods.
Chapter 13 allows for existing buildings to be evaluated to show that alterations or a change of occupancy, while not meeting new construction requirements, will provide a level of safety to demonstrate compliance. Provisions are based on a numerical scoring system involving 21 safety parameters where, when evaluated, such buildings must meet a minimum overall safety score.
CEBC § 422.3 High relevance — show source text
503 A .16 Reserved.
503 A .17 Ambulatory care facilities. Where a work area exceeds 50 percent of the building area and the work area includes an existing ambulatory care facility, the following shall be provided:
- A smoke compartment in accordance with Section 422.3 of the California Building Code where the alteration results in an ambulatory care facility greater than 10,000 square feet on one story.
- Separation from adjacent spaces in accordance with Section 422.2 of the California Building Code, where any such facility has the potential for four or more care recipients are to be incapable of self-preservation at any time.
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503 A .18 Reserved.
503 A .19 Reserved.
503 A .20 Two-way communications systems. Where the work area for alterations exceeds 50 percent of the building area and the building has elevator service, a two-way communication systems shall be provided where required by Section 1009.8 of the Califor- nia Building Code.
SECTION 504 A
RESERVED
SECTION 505 A
RESERVED
SECTION 506 A —CHANGE OF OCCUPANCY
506 A .1 Compliance. A change of occupancy shall not be made in any building unless that building is made to comply with the requirements of the California Building Code for the use or occupancy. Changes of occupancy in a building or portion thereof shall be such that the existing building is not less complying with the provisions of this code than the existing building or structure was prior to the change. Subject to the approval of the building official, changes of occupancy shall be permitted without complying with all of the requirements of this code for the new occupancy, provided that the new occupancy is less hazardous, based on life and fire risk, than the existing occupancy.
Exception: The building need not be made to comply with Chapter 16 A of the California Building Code unless required by Section 506 A .5.
506 A .1.1 Change in function . A change in function shall require compliance with all the functional requirements for new construc- tion in the California Building Code, including requirements in California Building Code Section 1224. Compliance shall be only as necessary to meet the specific provisions and is not intended to require the entire building be brought into compliance.
Exception: Minimum room clearances, areas and dimensions may meet the requirements of the 2001 California Building Code for existing rooms re-used for a similar purpose, subject to the approval of OSHPD.
506 A .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 A .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.
CEBC § 1.10.1 High relevance — show source text
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Chapter 3 Provisions for All Compliance Methods.
Chapter 3 guides the use of the three compliance methods of the CEBC and provides requirements that apply globally. The globally applicable requirement include general requirements related to buildings materials and other applicable codes, storm shelters, structural loads, in-situ load tests, accessibility, smoke alarms, carbon monoxide detection and exterior wall coverings.
Chapter 3A Provisions for All Compliance Methods.
Chapter 3A controls the compliance options for alteration, repair, addition, evaluation and change of occupancy of existing structures regulated by the Department of Health Care Access and Information/Office of Statewide Hospital Planning and Development, which include hospitals and correctional treatment centers (applications listed in Sections 1.10.1 (OSHPD 1).
Chapter 4 Repairs.
Chapter 4, a chapter independent of the three compliance methods, governs the repair of existing buildings. The provisions define conditions under which repairs may be made using materials and methods like those of the original construction or the extent to which repairs must comply with requirements for new buildings.
Chapter 4A Repairs.
Chapter 4A governs the repair of existing buildings regulated by the Department of Health Care Access and Information/Office of State- wide Hospital Planning and Development, which include hospitals and correctional treatment centers (applications listed in Sections 1.10.1 (OSHPD 1).
Chapter 5 Prescriptive Compliance Method.
Chapter 5 provides one of the three main options of compliance available in the CEBC for buildings and structures undergoing alteration, addition or change of occupancy. The base requirements are more administrative in nature. The structural triggers for upgrades are consistent with the Work Area Method.
Chapter 5A Prescriptive Compliance Method.
Chapter 5A provides details for the prescriptive compliance method for alteration, addition and change of occupancy of existing build- ings and structures regulated by the Department of Health Care Access and Information/Office of Statewide Hospital Planning and Development, which include hospitals and correctional treatment centers (applications listed in Sections 1.10.1 (OSHPD 1).
Chapter 6 Classification of Work.
Chapter 6 provides an overview of the Work Area Method and defines the different classifications of work including alterations, change of occupancy, additions and historic buildings. Detailed requirements for all of these are given in subsequent Chapters 7 through 11.
Chapter 7 Alterations—Level 1.
Chapter 7 provides the technical requirements for those existing buildings that undergo Level 1 alterations as described in Section 602, which includes replacement or covering of existing materials, elements, equipment or fixtures using new materials for the same purpose. This chapter is distinguished from Chapters 8 and 9 by only involving replacement of building components with new components with no reconfiguration of space.
Chapter 8 Alterations—Level 2.
A Level 2 alteration is an alteration involving space reconfiguration that could be up to and including 50 percent of the area of the building or addition of a new building system. Level 2 alterations also include the extension or addition of any system or equipment. The purpose of Chapter 8 is to provide detailed requirements and provisions to identify the required improvements in the existing building elements, means of egress, fire protection, structural systems, energy efficiency, and other building systems include electrical, mechanical and plumbing when a building is being altered.
Chapter 9 Alterations—Level 3.
CBC § 301 High relevance — show source text
The IEBC is a model code in the International Code family of codes intended to provide requirements for repair and alternative approaches for alterations, changes of occupancy and additions to existing buildings. A large number of existing buildings and structures do not comply with the current building code requirements for new construction. Although many of these buildings are potentially salvageable, rehabilitation is often cost-prohibitive because compliance with all the requirements for new construction could require extensive changes that go well beyond the value of the building or the original scope of the alteration. At the same time, it is necessary to regulate construction in existing buildings that undergo additions, alterations, extensive repairs or change of occupancy. Such activity represents an opportunity to ensure that new construction complies with the current building codes and that existing conditions are maintained, at a minimum, to their current level of compliance or are improved as required to meet basic safety levels. To accomplish this objective, and to make the alteration process easier, this code allows for options for controlled departure from full compliance with the International Codes dealing with new construction, while maintaining basic levels for fire safety, structural and life safety features of the rehabilitated building.
This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:
Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).
Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area Compliance Method given in Chapters 6 through 12.
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Option 3: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Performance Compliance Method given in Chapter 13. It should be noted that this option was also provided in the former Chapter 34 of the IBC (2012 and earlier editions).
Under limited circumstances, a building alteration can be made to comply with the laws under which the building was originally built, as long as the accessibility requirements are met, there has been no substantial structural damage and there will be limited structural alteration. Flood hazard provisions also must still be addressed where there is a substantial improvement.
Note that all repairs must comply with Chapter 4 and all relocated buildings are addressed by Chapter 14.
ARRANGEMENT AND FORMAT OF THE 2025 CEBC
The format of the CEBC allows each chapter to be devoted to a particular subject. The following table shows how the CEBC is divided. The subsequent table shows CEBC requirements that are correlated with other California Codes. The chapter synopses detail the scope and intent of the provisions of the CEBC.
CEBC § 506.5.1 High relevance — show source text
[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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Group U, the lateral force-resisting system of the building shall comply with Section 304.3.1 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 of the California Building Code or shall comply with ASCE 41 using an objective of Operational nonstructural performance with the BSE-1N earthquake hazard level.
Exceptions:
- Where the area of the new occupancy is less than 10 percent of the building area, the occupancy is not changing from a Group S or Group U occupancy, and the new occupancy is not assigned to Risk Category IV, compliance with this section is not required. The cumulative effect of occupancy changes over time shall be considered.
- Where a change of use results in a building being reclassified from Risk Category I or II to Risk Category III and the seismic coefficient, S DS, is less than 0.33, compliance with this section is not required.
- Unreinforced masonry bearing wall buildings assigned to Risk Category III and to Seismic Design Category A or B, shall be permitted to use Appendix Chapter A1 of this code.
- Where the change is from a Group S or Group U occupancy and there is no change of risk category, compliance with Section 304.3.2 shall be permitted.
[BS] 506.5.4 Access to Risk Category IV. Any structure that provides operational access to an adjacent structure assigned to Risk Category IV as the result of a change of occupancy shall itself comply with Sections 1608 and 1609 of the California Building Code and Section 304.3.1 of this code. Where operational access to the Risk Category IV structure is less than 10 feet (3048 mm) from either an interior lot line or from another structure, access protection from potential falling debris shall be provided.
CEBC § 4A-5 High relevance — show source text
408A Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4A-5
CHAPTER 5 PRESCRIPTIVE COMPLIANCE METHOD . . . . . 5-3
501 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
502 Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
503 Alterations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
504 Fire Escapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
505 Windows and Emergency Escape Openings . . . . . . . 5-8
506 Change of Occupancy. . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
507 Historic Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
CHAPTER 5A [OSHPD 1] PRESCRIPTIVE COMPLIANCE
METHOD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-3
501A General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-3
502A Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-4
503A Alterations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-5
504A Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-7
505A Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-7
506A Change of Occupancy. . . . . . . . . . . . . . . . . . . . . . . . . . . .5A-7
CHAPTER 6 CLASSIFICATION OF WORK . . . . . . . . . . . . . . . 6-3
CEBC § 1001.1 High relevance — show source text
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10 CHANGE OF OCCUPANCY
User notes:
About this chapter : The purpose of this chapter is to provide regulations for the circumstances where an existing building is subject to a change of occupancy or a change of occupancy classification. A change of occupancy is not to be confused with a change of occupancy classification. The California Building Code defines different occupancy classifications in Chapter 3 and special occupancy requirements in Chapter 4. Within specific occupancy classifications there can be many different types of actual activities that can take place. For instance, a Group A-3 occupancy classification deals with a wide variation of different types of activities, including bowling alleys and courtrooms, indoor tennis courts and dance halls. When a facility changes use from, for example, a bowling alley to a dance hall, the occupancy classification remains A-3, but the different uses could lead to drastically different code requirements. Therefore, this chapter deals with the special circumstances that are associated with a change in the use of a building within the same occupancy classification as well as a change of occupancy classification.
SECTION 1001—GENERAL
1001.1 Scope. The provisions of this chapter shalle a change of occupancy occurs, as defined in Section 202.
1001.2 Certificate of occupancy. A change of occupancy or a change of occupancy within a space where there is a different fire protection system threshold requirement in Chapter 9 of th apply where current California Building Code than exists in the current building or space shall not be made to any structure without the approval of the code official. A certificate of occupancy shall be issued where it has been determined that the requirements for the change of occupancy have been met.
1001.2.1 Change of use. Any work undertaken in connection with a change in use shall conform to the applicable requirements for the work as classified in Chapter 6 and to the requirements of Sections 1002 through 1010.
1001.2.2 Change of occupancy classification. Where a building undergoes a change of occupancy classification, the provisions of Sections 1002 through 1011 shall apply.
1001.2.2.1 Partial change of occupancy. Where a portion of an existing building undergoes a change of occupancy classification, Section 1011 shall apply.
1001.3 Certificate of occupancy required. A certificate of occupancy shall be issued where a change of occupancy occurs that results in a different occupancy classification as determined by the California Building Code .
SECTION 1002—SPECIAL USE AND OCCUPANCY
1002.1 Compliance with the building code. Where an existing building or part of an existing building undergoes a change of occupancy to one of the special use or occupancy categories as described in Chapter 4 in the California Building Code, the building shall comply with all of the requirements of Chapter 4 of the California Building Code applicable to the special use or occupancy.
1002.2 Incidental uses. Where a portion of a building undergoes a change of occupancy to one of the incidental uses listed in Table 509.1 of the California Building Code, the incidental use shall comply with Section 509 of the California Building Code applicable to the incidental use.
SECTION 1003—BUILDING ELEMENTS AND MATERIALS
1003.1 General. Building elements and materials in portions of buildings undergoing a change of occupancy classification shall comply with Section 1011.
SECTION 1004—FIRE PROTECTION
CEBC § 1.1 High relevance — show source text
Exception: The building need not be made to comply with Chapter 16 A of the California Building Code unless required by Section 506 A .5.
506 A .1.1 Change in function . A change in function shall require compliance with all the functional requirements for new construc- tion in the California Building Code, including requirements in California Building Code Section 1224. Compliance shall be only as necessary to meet the specific provisions and is not intended to require the entire building be brought into compliance.
Exception: Minimum room clearances, areas and dimensions may meet the requirements of the 2001 California Building Code for existing rooms re-used for a similar purpose, subject to the approval of OSHPD.
506 A .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 A .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 A .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:
- 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).
- 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.
CEBC § 505.2 High relevance — show source text
20|||X|||||||||||||||||||||| |504|||X|†|†|†|||||X|X||X|X|||||||||| |505|||X||||||||X|X||X|X|||||||||| |505.2||||X|X|||||||||||||||||||| |506|||||||||||X|X||X|X|||||||||| |506.1 –506.1.1|X||X|||||||||||||||||||||| |506.1.2|||||||||||X|X||X|X|||||||||| |506.2 – 506.3|X||X|||||||||||||||||||||| |506.4|||X|||||||||||||||||||||| |506.5_ Exception_|X|||||||||||||||||||||||| |506.6||||†|†|†|||||||||||||||||||
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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5 PRESCRIPTIVE COMPLIANCE METHOD
User notes:
About this chapter: Chapter 5 provides details for the prescriptive compliance method—one of the three main options of compliance available in this code for buildings and structures undergoing alteration, addition or change of occupancy.
SECTION 501—GENERAL
501.1 Scope. The provisions of this chapter shall control the alteration, addition and change of occupancy of existing buildings and structures, including historic buildings and structures, [BSC] including state-regulated structures in accordance with Section 501.1.2. Historic buildings and structures shall comply with Part 8, Title 24, C.C.R.
Exceptions: 1. [HCD 2] For relocated or moved buildings and maintenance, alteration, repair, addition or change of occupancy to existing buildings and accessory structures in mobilehome parks or special occupancy parks as provided in Section 1.8.2.1.3. See California Code of Regulations, Title 25, Division 1, Chapters 2 and 2.2. 2. [HCD 1] Limited-density owner-built rural dwellings.
[HCD 1] In addition to the requirements in this chapter, maintenance, alteration, repair, addition or change of occupancy to existing buildings and accessory structures under the authority of the Department of Housing and Community Development, as provided in Section 1.8.2.1.1, shall comply with California Code of Regulations, Title 25, Division 1, Chapter 1, Subchapter 1.
501.1.1 Compliance with other methods. Alterations, additions and changes of occupancy to existing buildings and structures shall comply with the provisions of this chapter or with one of the methods provided in Section 301.3.
501.1.2 Existing state-owned structures. [BSC] The provisions of Sections 317 through 322 establish minimum standards for earth- quake evaluation and design for retrofit of existing state-owned structures, including buildings owned by the University of California, the California State University and the Judicial Council.
CBC § 301 High relevance — show source text
This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:
Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).
Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area Compliance Method given in Chapters 6 through 12.
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Option 3: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Performance Compliance Method given in Chapter 13. It should be noted that this option was also provided in the former Chapter 34 of the IBC (2012 and earlier editions).
Under limited circumstances, a building alteration can be made to comply with the laws under which the building was originally built, as long as the accessibility requirements are met, there has been no substantial structural damage and there will be limited structural alteration. Flood hazard provisions also must still be addressed where there is a substantial improvement.
Note that all repairs must comply with Chapter 4 and all relocated buildings are addressed by Chapter 14.
ARRANGEMENT AND FORMAT OF THE 2025 CEBC
The format of the CEBC allows each chapter to be devoted to a particular subject. The following table shows how the CEBC is divided. The subsequent table shows CEBC requirements that are correlated with other California Codes. The chapter synopses detail the scope and intent of the provisions of the CEBC.
CHAPTER TOPICS Col2 CHAPTER SUBJECTS 1, 2 Administrative Requirements and Definitions 3 Provisions for all Compliance Methods 4 Repairs 5 Prescriptive Compliance Method for Existing Buildings 6–11 Work Area Compliance Method for Existing Buildings 13 Performance Compliance Method for Existing Buildings 14 Relocated Buildings 15 Construction Safeguards 16 Referenced Standards Appendix A Guidelines for Seismic Retrofit of Existing Buildings Appendix B Supplementary Accessibility Requirements for Existing Buildings Appendix C Guidelines for Wind Retrofit of Existing Buildings Appendix D Board of Appeals Appendix E Temporary Emergency Uses Resource A Guidelines on Fire Ratings of Archaic Materials and Assemblies CALIFORNIA BUILDING CODE CORRELATED TOPICS
The CEBC requirements for construction safeguards are directly correlated to the requirements of the CBC. The following table shows chapters of the CBC that are correlated with the CEBC:
CEBC/CBC CORRELATED TOPICS Col2 Col3 CEBC CHAPTER/SECTION CBC CHAPTER/SECTION SUBJECT Chapter 15 Chapter 33 Construction safeguards Chapter 1 Scope and Administration.
Chapter 1 establishes the limits of applicability of the code and describes how the code is to be applied and enforced. The provisions of Chapter 1 establish the authority and duties of the code official appointed by the authority having jurisdiction and also establish the rights and privileges of the design professional, contractor and property owner.
Chapter 2 Definitions.
Frequently asked questions
What is the first thing I should do when proposing a change of occupancy?
Start by classifying the new occupancy and determining the area of the building affected; then review § 506.1 and the structural triggers in § 506.5 to see which upgrades and exceptions apply, and consult the code official early .
Do small partial changes ever trigger major upgrades?
Yes—if the changed area exceeds 10 percent of the building area or the change raises the building’s Risk Category, structural and seismic upgrades under § 506.5 can be required. Also watch cumulative changes over time .
When do I need to upgrade windows for emergency escape?
If the new occupancy requires an emergency escape and rescue opening, existing operable windows used for that purpose must meet 4 sq ft / 22 in / 20 in minima or be replaced per § 506.4 .
Are acoustic upgrades ever required?
Yes — in Group E occupancies where the work area exceeds 50 percent of the building area, classrooms with volumes ≤ 20,000 cu ft must have enhanced classroom acoustics per § 506.6 .
Can the code official allow a less‑than‑full upgrade?
Yes — § 506.1 allows the code official to permit changes without complying with all new‑construction requirements when the new occupancy is less hazardous, but this is discretionary and must be approved .
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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