CEBC · California Existing Building Code

Can an addition create or extend a nonconforming condition?

Short answer for a homeowner: Under the California Existing Building Code, an addition cannot make an existing building's safety, accessibility, or mechanical systems worse — you either must avoid relying on noncompliant parts of the building or fix them. The code’s key rule is **§ 1101.2**, and there are limited, specific exceptions (for certain nonstructural supports and some flood‑zone cases); structural elements overloaded by more than **5%** generally must be upgraded.

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Last reviewed: July 6, 2026

What the code requires

An addition must not create or extend a nonconformity in the existing building with respect to accessibility, structural strength, supports and attachments for nonstructural components, fire safety, means of egress, or the capacity of mechanical, plumbing or electrical systems — this is the plain-English rule in § 1101.2 of the CEBC.
In short: you can add on, but the addition may not make any of the listed building deficiencies worse or expand their effect into the new work.

The single most important rule: an addition cannot cause the existing building’s accessibility, structural, egress, fire or life‑safety systems, or MEP capacities to become more nonconforming than they already are.

Requirements in detail

Core prohibition (plain rule)

  • The CEBC states directly in § 1101.2 that an addition "shall not create or extend any nonconformity" in the listed categories. § 1101.2 is the controlling requirement for additions.

What "create or extend" means for practical decision-making

  • "Create" — the addition may not introduce a new deficiency in the existing building (for example, an added mechanical load that overwhelms existing electrical service and causes the building's electrical system to be nonconforming for the first time). § 1101.2.
  • "Extend" — the addition may not enlarge the scope or effect of an existing nonconformity (for example, you may not connect a new occupied space to a corridor that is already nonconforming for egress capacity such that the nonconformity now affects more occupants). § 1101.2.

Quick decision table — dimensions that matter

Decision dimension What to check If threshold exceeded or worsened Code Reference
Accessibility (egress paths, doors, routes) Will the addition rely on or change existing accessible routes, door clearances, ramp slopes, or number of accessible elements? Addition may not create or extend an accessibility nonconformity. § 1101.2. § 1101.2
Structural strength (gravity/lateral) Do loads from the addition increase demand on existing structural elements? If existing gravity members see an increase in design dead/live/snow loads > 5 percent, they must be replaced or altered per CEBC additions provisions. § 502.3 / § 1101.2
Supports & attachments for nonstructural components Will the addition require existing attachments (pipe/duct/equipment supports) to carry new loads? These supports must not be made more nonconforming — but there is a limited exception (see next row). § 1101.2 (exception noted)
Exception for nonstructural supports Nonconforming supports/attachments that serve the addition from within the existing building need not be altered unless they are part of the addition’s life‑safety system or serve Risk Category IV additions. § 1101.2 Exception
Fire safety & means of egress Does the addition change occupant load, travel distance, or require new fire separations or sprinklers? Cannot create or extend fire/egress nonconformity; additions that increase fire area may trigger Chapter 9 compliance. § 1101.2, § 1102.3
MEP capacity Will plumbing, mechanical or electrical systems be overloaded by the addition? Addition cannot create or extend a capacity-related nonconformity; if systems serving the addition are inadequate, they must be upgraded. § 1101.2

How the CEBC interfaces with other addition rules

  • Additions otherwise must comply with new-construction requirements of the California Building Code, but the existing building is not broadly forced to meet all new-construction code requirements except where a provision in the additions chapter requires it (see § 1101.1 and related text).
  • Risk category changes due to mixed occupancies or additions can trigger broader compliance for the addition and systems that serve it (see § 1101.3).

Exceptions & special cases

  • Nonstructural supports/attachments exception: Nonconforming supports and attachments for nonstructural components that serve the addition from within the existing building need not be altered to comply with CBC Section 1613 unless they are part of the addition's life‑safety system or are required to serve an addition assigned to Risk Category IV. This exception is stated directly in the CEBC addition provisions.
  • Flood hazard/substantial improvement: where additions are in mapped flood hazard areas, CEBC and related flood provisions permit some nonstructural additions only if they do not create or extend flood‑resistance nonconformity and meet specified floor-elevation rules; if the combined work is a substantial improvement, new‑construction flood requirements apply to the whole building. See CEBC flood provisions and implementing sections.
  • Structural load increases: existing gravity-carrying elements that will experience an increase in design dead, live or snow load (including snow drift effects) of more than 5 percent because of an addition must be replaced or altered to meet new‑construction gravity requirements. That numerical threshold is explicitly stated in the CEBC additions provisions (see Section addressing existing structural elements).
  • Risk category jump: where assigning risk categories (per occupancy) results in a higher risk category than existed before, CEBC treats that as a change of occupancy and may require Chapter 10 compliance or CBC new‑construction compliance for the higher risk category as stated in § 1101.3.

Common mistakes

  • Confusing zoning nonconformance with CEBC nonconformity. CEBC §1101.2 deals with building code nonconformities (structural, egress, accessibility, MEP, fire safety), not local zoning setbacks or lot coverage. (See separate ADU/zoning guidance — zoning nonconformities are a different administrative issue.)
  • Forgetting the 5 percent structural trigger. Designers sometimes overlook the CEBC threshold that an increase in gravity loads over 5 percent on an existing element generally requires replacement or alteration.
  • Assuming all nonstructural attachments must be upgraded. There is a specific exception for nonstructural supports serving the addition from within the existing building — but it does not apply where those supports are part of the addition’s life‑safety system or the addition is Risk Category IV.
  • Treating an addition as completely independent: if the addition is structurally connected or relies on existing means of egress, you must evaluate the combined condition for nonconformity per § 1101.2 and related sections.

Worked example — a concrete scenario

Scenario: An existing two‑story office building has an existing corridor that is nonconforming for current accessible egress (corridor clear width is below current CBC accessibility requirements). The owner wants to add a 1,200 ft² horizontal addition on the same floor that connects into that corridor and increases occupant load by 24 people.

Step‑through:

  1. CEBC rule: § 1101.2 prohibits an addition from creating or extending a nonconformity in means of egress. The proposed connection would expand the number of occupants relying on the already‑nonconforming corridor, so this risks "extending" the nonconformity.
  2. Practical effect: the designer must either (a) provide an alternate means of egress for the addition that does not rely on the nonconforming corridor, or (b) bring the corridor into compliance (upgrade width/clearances) so the addition does not extend the egress nonconformity. § 1101.2 requires one of these outcomes.
  3. Structural check: the addition’s new roof and live loads increase the tributary loads on a nearby existing beam. The structural analysis shows an 8% increase in design dead + live load on that existing beam. Because this exceeds the 5 percent threshold, CEBC requires the existing gravity‑load element to be replaced or altered to carry new loads required for new construction. See CEBC additions structural provisions (Section addressing existing structural elements and the 5% threshold). Outcome: To proceed without extending nonconformity the owner must either redesign the addition so it does not rely on the deficient corridor and must strengthen/alter the overloaded beam (since +8% > 5 percent) to meet the CEBC requirement.

Related provisions

  • § 1101.1 — Scope; applicability of new‑construction rules to additions and how additions interact with the existing building.
  • § 1101.3 — Risk category assignment where the addition and existing building have different occupancies; may trigger additional compliance.
  • § 1102.1 — An addition shall not increase height beyond permitted limits for new buildings (height control related to additions).
  • § 1102.2 — Area limitations for additions (area control related to additions).
  • § 1102.3 — Existing fire areas increased by addition shall comply with Chapter 9 (fire protection systems).
  • § 502.1.2 (Chapter 5 additions) — Parallel prescriptive statement: an addition shall not create or extend any nonconformity; includes similar exception language.
  • Structural existing‑elements provisions — see CEBC sections addressing existing gravity/lateral element evaluation and the 5 percent gravity load increase threshold.
  • Flood hazard/addition guidance (CEBC performance/flood provisions) — additions in flood hazard areas must not create/extend flood‑resistance nonconformity unless new‑construction flood requirements apply.

Code references

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

  • 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 § 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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    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 § 1101.5 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 § 1303.1 High relevance — show source text

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    SECTION 1303—ACCEPTANCE

    1303.1 General. For repairs, alterations, additions and changes of occupancy to existing buildings that are evaluated in accordance with this section, compliance with this section shall be accepted by the code official.

    1303.1.1 Hazards. Where the code official determines that an unsafe condition exists as provided for in Section 115, such unsafe condition shall be abated in accordance with Section 115.

    1303.1.2 Compliance with other codes. Buildings that are evaluated in accordance with this section shall comply with the Inter- national Fire Code and International Property Maintenance Code .

    [BS] 1303.1.3 Compliance with flood hazard provisions. In flood hazard areas, buildings that are evaluated in accordance with this section shall comply with Section 1612 of the International Building Code, or Section R306 of the International Residential Code, as applicable, if the work covered by this section constitutes substantial improvement. If the work covered by this section is a structurally connected horizontal addition that does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply.

    1. The addition shall not create or extend any nonconformity of the existing building 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 the lowest floor elevation required in Section 1612 of the International Building Code or Section R306 of the International Residential Code, as applicable.

    SECTION 1304—INVESTIGATION AND EVALUATION

    1304.1 General. For proposed work covered by this chapter, the building owner shall cause the existing building to be investigated and evaluated in accordance with the provisions of Sections 1304.1 through 1307.1.

    [BS] 1304.1.1 Structural analysis. The owner shall have a structural analysis of the existing building made to determine adequacy of structural systems for the proposed alteration, addition or change of occupancy. The analysis shall demonstrate that the building with the work completed is capable of resisting the loads specified in Chapter 16 of the International Building Code .

    1304.1.2 Submittal. The results of the investigation and evaluation as required in Section 1304.1, along with proposed compliance alternatives, shall be submitted to the code official.

    1304.1.3 Determination of compliance. The code official shall determine whether the existing building, with the proposed addition, alteration or change of occupancy, complies with the provisions of this section in accordance with the evaluation process in Sections 1305.1 through 1307.1.

    SECTION 1305—SCORING AND EVALUATION

    1305.1 Safety categories. The evaluation shall be composed of three categories: fire safety, means of egress and general safety, as defined in Sections 1305.1.1 through 1305.1.3.

    1305.1.1 Fire safety. Included within the fire safety category are the structural fire resistance, automatic fire detection, fire alarm, automatic sprinkler system and fire suppression system features of the facility.

    1305.1.2 Means of egress. Included within the means of egress category are the configuration, characteristics and support features for means of egress in the facility.

  • 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 § 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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    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 § 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 § 1302.1.3 High relevance — show source text

    1302.1.3 Additions. Additions to existing buildings shall comply with the requirements of the International Building Code or the International Residential Code for new construction. The combined height and area of the existing building and the new addition shall not exceed the height and area allowed by Chapter 5 of the International Building Code . Where a fire wall that complies with Section 706 of the International Building Code is provided between the addition and the existing building, the addition shall be considered a separate building. Where a new occupiable roof is added to a building or structure, the occupiable roof shall comply with the provisions of the International Building Code .

    Exception: In-filling of floor openings and nonoccupiable appendages, such as elevator and exit stairway shafts, shall be permitted beyond that permitted by the International Building Code .

    1302.1.4 Alterations. An existing building or portion thereof shall not be altered in such a manner that results in the building being less safe or sanitary than such building is currently.

    Exception: Where the current level of safety or sanitation is proposed to be reduced, the portion altered shall conform to the requirements of the International Building Code .

    1302.1.5 Escalators. Where escalators are provided in below-grade transportation stations, existing and new escalators shall be permitted to have a clear width of less than 32 inches (815 mm).

    1302.1.6 Plumbing fixtures. Plumbing fixtures shall be provided in accordance with Section 1009 for a change of occupancy and Section 808 for alterations. Plumbing fixtures for additions shall be in accordance with the International Plumbing Code .

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    SECTION 1303—ACCEPTANCE

    1303.1 General. For repairs, alterations, additions and changes of occupancy to existing buildings that are evaluated in accordance with this section, compliance with this section shall be accepted by the code official.

    1303.1.1 Hazards. Where the code official determines that an unsafe condition exists as provided for in Section 115, such unsafe condition shall be abated in accordance with Section 115.

    1303.1.2 Compliance with other codes. Buildings that are evaluated in accordance with this section shall comply with the Inter- national Fire Code and International Property Maintenance Code .

    [BS] 1303.1.3 Compliance with flood hazard provisions. In flood hazard areas, buildings that are evaluated in accordance with this section shall comply with Section 1612 of the International Building Code, or Section R306 of the International Residential Code, as applicable, if the work covered by this section constitutes substantial improvement. If the work covered by this section is a structurally connected horizontal addition that does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply.

    1. The addition shall not create or extend any nonconformity of the existing building 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 the lowest floor elevation required in Section 1612 of the International Building Code or Section R306 of the International Residential Code, as applicable.

    SECTION 1304—INVESTIGATION AND EVALUATION

  • CEBC § 5A-4 High relevance — show source text

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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. Any existing gravity load-carrying structural element whose vertical load-carrying capacity is decreased as part of the addition and its related alterations shall be considered to be an altered element subject to the requirements of Section 503 A .3. Any existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements of Section 502A.4 .

    502 A .4 Existing structural elements carrying lateral load. Where the addition is structurally independent of the existing structure, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing structure, the lateral force-resisting system of the existing structure and its addition acting together as a single structure shall comply with Section 1609 A and 1613A of the California Building Code .

    Exceptions: For incidental and minor additions:

    1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 A and 1613 A of the California Building Code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction. When calculating demand-capacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 A of the California Building Code or the code wind forces in effect at the time.
  • CEBC § 304.3.1 High relevance — show source text

    Exceptions:

    1. Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes where the existing building and the addition comply with the conventional light-frame construction methods of the Cali- fornia Building Code or the provisions of the California Residential Code .
    2. Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Section 1609 of the California Building Code and Section 304.3.1 of this code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction.

    When calculating demand-capacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 of the California Building Code or the code wind forces in effect at the time. When calculating demand-capacity ratios for earthquake, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 304.3.1 or the full seismic forces in effect at the time.

    [BS] 1103.3 Flood hazard areas. Additions and foundations in flood hazard areas shall comply with the following requirements:

    1. For horizontal additions that are structurally interconnected to the existing building: 1.1. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.2. If the addition constitutes substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.3. If the addition does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply: 1.3.1. The addition shall not create or extend any nonconformity of the existing building with the flood-resistant construction requirements. 1.3.2. The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or the lowest floor elevation required in Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
    2. For horizontal additions that are not structurally interconnected to the existing building: 2.1. The addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Resi- dential Code, as applicable. 2.2. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
    3. For vertical additions and all other proposed work that, when combined, constitute substantial improvement, the existing building shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.
  • CEBC § 1.2. High relevance — show source text

    1.2. If the addition constitutes substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.3. If the addition does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply: 1.3.1. The addition shall not create or extend any nonconformity of the existing building with the flood-resistant construction requirements. 1.3.2. The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or the lowest floor elevation required in Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 2. For horizontal additions that are not structurally interconnected to the existing building: 2.1. The addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Resi- dential Code, as applicable. 2.2. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 3. For vertical additions and all other proposed work that, when combined, constitute substantial improvement, the existing building shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 4. For a new foundation, replacement foundation or a foundation raised or extended upward, the foundation shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.

    SECTION 1104—ENERGY CONSERVATION

    1104.1 Minimum requirements. Additions to existing buildings shall comply with applicable provisions of the California Energy Code (Part 6, Title 24, C.C.R).

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    12 HISTORIC BUILDINGS

    Chapter 12 is not adopted by the State of California.

    Historic buildings and structures shall comply with Part 8, Title 24, California Code of Regulations.

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    CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 13 – PERFORMANCE COMPLIANCE METHODS

    Not adopted by the State of California (May be available for adoption by local ordinance. See Section 1.1.11.) (See Section 104.11 for consideration of alternative means of compliance.)

  • CEBC § 2-6 High relevance — show source text

    For purposes of this definition, work done to implement repairs shall not be considered damage that reduces structural capacity.

    SUBSTANTIAL STRUCTURAL DAMAGE. [OSHPD 1 & 1R] A condition where any of the following apply: 1. The vertical elements of the lateral force-resisting system have suffered damage such that the lateral load carrying capacity of any story in any horizontal direction has been reduced by more than 10 percent from its predamage condition. 2. The capacity of any vertical component carrying gravity load, or any group of such components, has a tributary area more than 15 percent of the total area of the structure’s floor(s) and roof(s), has been reduced more than 10 percent from its predamage condition, and the remaining capacity of such affected elements, with respect to all dead and live loads, is less than 75 percent of that required by the California Building Code for new buildings of similar structure, purpose and location. 3. The capacity of any structural component carrying snow load, or any group of such components, that supports more than 15 percent of the roof area of similar construction, has been reduced more than 10 percent from its predamage condition, and the

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    DEFINITIONS

    remaining capacity with respect to dead, live and snow loads is less than 75 percent of that required by the California Building Code for new buildings of similar structure, purpose and location.

    TECHNICALLY INFEASIBLE. An alteration of a facility that has little likelihood of being accomplished because the existing structural conditions require the removal or alteration of a load-bearing member that is an essential part of the structural frame, or because other existing physical or site constraints prohibit modification or addition of elements, spaces or features which are in full and strict compliance with the minimum requirements for new construction and which are necessary to provide accessibility.

    UNREINFORCED CONCRETE. [OSHPD 1, 1R, 2, 4 & 5] Unreinforced concrete as used in this chapter means plain concrete as defined in ACI 318 Section 2.3.

    UNREINFORCED MASONRY. [OSHPD 1, 1R, 2, 4 & 5] Unreinforced masonry as used in this chapter means masonry construction where reinforcements in any direction is less than minimum reinforcement specified in TMS 402 Section 7.3.2.6.

    UNSAFE. Buildings, structures or equipment that are unsanitary, or that are deficient due to inadequate means of egress facilities, inadequate light and ventilation, or that constitute a fire hazard, or in which the structure or individual structural members meet the definition of “Dangerous,” or that are otherwise dangerous to human life or the public welfare, or that involve illegal or improper occupancy or inadequate maintenance shall be deemed unsafe. A vacant structure that is not secured against entry shall be deemed unsafe.

    [HCD 1 & HCD 2] An unsafe building, as defined in this chapter, shall be considered substandard.

Frequently asked questions

Can I connect a new addition to an existing nonconforming corridor if I limit occupant use of the addition?

No. Connecting the addition so that occupants rely on that corridor will likely "extend" the existing means‑of‑egress nonconformity. You must either provide an alternate compliant egress or bring the affected egress into compliance so the addition does not extend the nonconformity as required by § 1101.2.

Do I always have to upgrade existing nonstructural supports (pipe/duct hangers) when I add on?

Not always. The CEBC exception to § 1101.2 allows nonconforming supports and attachments for nonstructural components that serve the addition from within the existing building to remain unaltered — unless they are part of the addition’s life‑safety system or are required to serve an addition assigned to Risk Category IV.

What if my addition increases loads on an existing beam by 6%?

Because the increase exceeds 5 percent, the CEBC requires that existing gravity load‑carrying elements be replaced or altered as needed to carry the gravity loads required for new construction — you must upgrade the element.

If an addition is in a flood zone, can I build without raising the new floor?

Possibly, but only if the addition does not create or extend the building’s nonconformity with flood‑resistant construction requirements and the lowest floor of the addition meets the CEBC elevation rule (lowest of existing lowest floor or required elevation). If the combined work is a substantial improvement, full flood design for new construction applies. See CEBC flood provisions.

Who decides whether an addition “creates or extends” a nonconformity?

The code official evaluates the proposed work using the CEBC provisions; the owner must submit investigations/evaluations (structural reports, etc.) as required by the CEBC so the official can determine compliance. See CEBC sections on investigation and submittal.

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