CRC · California Residential Code
Energy for alterations, additions and existing buildings
This hub summarizes how the CRC treats energy compliance for additions, alterations and repairs—covering scope, prescriptive vs. performance paths, key sections, common exceptions and the role of energy budgets.
Last reviewed: July 6, 2026
Overview
This part of the California Residential Code (Title 24, Part 6 as applied to residential work) sets the energy rules that apply when you add to, alter, repair or otherwise do new work on existing buildings — including single‑family, multifamily and mixed‑use situations. It explains which mandatory measures and installation requirements apply, and whether the project must follow a prescriptive path or a performance (energy‑budget/LSC) approach. See the single‑family additions/alterations requirements at §150.2 , multifamily requirements at §180.0/§180.1 , and nonresidential/hotel provisions for work in existing buildings at §141.0 .
Key concepts you’ll encounter here include the “existing + altered + addition” standard‑design rules used for energy‑budget (LSC) compliance, how altered components are modeled or brought up to required levels, and where limited exceptions apply for small additions or retained existing systems. The energy budget method for additions is expressed in Long‑Term System Cost (LSC) terms and explained in the budget/calculation sections (see §100.2 and supporting rules) . Mandatory measures and device requirements from Part 6 (for example Sections 110.0 and 150.0) also continue to apply to many additions and alterations .
Practically, this means: small additions may qualify for specific exceptions, many additions must meet either prescribed prescriptive requirements or be included in a performance compliance run that combines existing, altered and new components, and ventilation/indoor‑air rules for additions are explicitly called out (see the whole‑dwelling and local exhaust provisions in §150.0(o)) .
In this section
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 150.1 High relevance — show source text
- Performance approach. The energy budget for additions is expressed in terms of long-term system cost (LSC). Performance calculations shall meet the requirements of Section 150.1(a) through (c), pursuant to the applicable requirements in Items A, B and C below.
A. For additions alone. The addition complies if the addition alone meets the energy budgets as specified in Section 150.1(b). B. Existing plus alteration plus addition. The standard design for existing plus alteration plus addition energy use is the combination of the existing building’s unaltered components to remain; existing building altered components that are the more efficient, in LSC energy, of either the existing conditions or the requirements of Section 150.2(b)2; plus the proposed addition’s energy use meeting the requirements of Section 150.2(a)1. The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered components’ energy features, plus the proposed energy features of the addition. Exception to Section 150.2(a)2B: Existing structures with a minimum R-11 insulation in framed walls showing compliance with Section 150.2(a)2 are not required to comply with Section 150.0(c). C. Mechanical ventilation for indoor air quality. Additions to existing buildings shall comply with Section 150.0(o) subject to the requirements specified in Subsections i and ii below. i. Whole-dwelling unit mechanical ventilation. a. Dwelling units that meet the conditions in Subsection 1 or 2 below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F.
- Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1000 square feet.
- Junior accessory dwelling units (JADU) that are additions to an existing building. b. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by more than 1,000 square feet shall have mechanical ventilation airflow in accordance with Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the entire dwelling unit comprised of the existing dwelling unit conditioned floor area plus the addition conditioned floor area. c. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. ii. Local mechanical exhaust. Additions to existing buildings shall comply with all applicable requirements specified in Sections 150.0(o)1G and 150.0(o)2.
D. Space-conditioning load calculations and system capacity. Additions to existing buildings shall comply with all applicable requirements specified in Section 150.2(a)1E.
2025 CALIFORNIA ENERGY CODE 189
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS
CRC § 160.2 High relevance — show source text
iii. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 160.2(b)2Aiv or 160.2(b)2Av as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. B. Local mechanical exhaust . Additions to existing buildings shall comply with all applicable requirements specified in Sections 160.2(b)2Avi and 160.2(b)2B. 3. Water heater. When additional water-heating equipment is installed to serve a dwelling unit as part of the addition, one of the following types of water heaters shall be installed: A. A water-heating system that meets the requirements of Section 170.2(d); or B. A water-heating system determined by the Executive Director to use no more energy than the one specified in Item A above.
(b) Performance approach. Performance calculations shall meet the requirements of Sections 170.0 through 170.2(a), pursuant to the applicable requirements in Items 1, 2 and 3 below.
- For additions alone. The addition complies if the addition alone meets the energy budgets expressed in terms of long-term system cost (LSC) energy.
- Existing plus alteration plus addition. The standard design for existing plus alteration plus addition energy use is the combination of the existing building’s unaltered components to remain; existing building altered components that are the more efficient, in LSC energy, of either the existing conditions or the requirements of Section 180.2(c); plus the proposed addition’s energy use meeting the requirements of Section 180.1(a). The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered components’ energy features, plus the proposed energy features of the addition. Exception to Section 180.1(b)2: Existing structures with a minimum R-11 insulation in framed walls showing compliance with Section 180.1(b) are not required to show compliance with Section 160.1(b).
- Mechanical ventilation for indoor air quality . Additions to existing buildings shall comply with Section 160.2 subject to the requirements specified in Subsections A and B below. When field verification and diagnostic testing are required by Section 180.1(b)3, buildings with three habitable stories or fewer shall use the applicable procedures in the Residential Appendices, and buildings with four or more habitable stories shall use the applicable procedures in Nonresidential Appendices NA1 and NA2.
272 2025 CALIFORNIA ENERGY CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS
A. Whole-dwelling unit mechanical ventilation . i. Dwelling units that meet the conditions in Subsection a or b below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 160.2(b)2Aiv or 160.2(b)2Av. a. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1000 square feet. b. Junior accessory dwelling units (JADU) that are additions to an existing building. ii.
CRC § 150.0 High relevance — show source text
MANDATORY FEATURES AND DEVICES. . . . . . . . . . . . . . . 159
150.0 Mandatory Features and Devices. . . . . . . . . . . . . . . .159
2025 CALIFORNIA ENERGY CODE vii
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CONTENTS
SUBCHAPTER 8 SINGLE-FAMILY RESIDENTIAL BUILDINGS—
PERFORMANCE AND PRESCRIPTIVE COMPLIANCE
APPROACHES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
150.1 Performance and Prescriptive Compliance Approaches for Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
SUBCHAPTER 9 SINGLE-FAMILY
RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS
TO EXISTING RESIDENTIAL BUILDINGS . . . . . . . . . . . . . . 187
150.2 Energy Efficiency Standards for Additions and Alterations to Existing Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
SUBCHAPTER 10 MULTIFAMILY BUILDINGS—MANDATORY
REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
160.0 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
160.1 Mandatory Requirements for Building Envelopes . . . 199
160.2 Mandatory Requirements for Ventilation and Indoor Air Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
160.3 Mandatory Requirements for Space-Conditioning Systems in Multifamily Buildings. . . . . . . . . . . . . . . 212
160.4 Mandatory Requirements for Water-Heating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
160.5 Mandatory Lighting Requirements for Indoor and Outdoor Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
160.6 Mandatory Requirements for Electric Power Distribution Systems . . . . . . . . . . . . . . . . . . . . . . . . . 232
160.7 Mandatory Requirements for Covered
Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
160.8 Mandatory Requirements for Solar Ready Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
CRC § 150.0 High relevance — show source text
- Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1000 square feet.
- Junior accessory dwelling units (JADU) that are additions to an existing building. b. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by more than 1,000 square feet shall have mechanical ventilation airflow in accordance with Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the entire dwelling unit comprised of the existing dwelling unit conditioned floor area plus the addition conditioned floor area. c. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. ii. Local mechanical exhaust. Additions to existing buildings shall comply with all applicable requirements specified in Sections 150.0(o)1G and 150.0(o)2.
D. Space-conditioning load calculations and system capacity. Additions to existing buildings shall comply with all applicable requirements specified in Section 150.2(a)1E.
2025 CALIFORNIA ENERGY CODE 189
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS
(b) Alterations. Alterations to existing single-family residential buildings or alterations in conjunction with a change in building occupancy to a single-family residential occupancy shall meet either Item 1 or 2 below.
- Prescriptive approach. The altered component and any newly installed equipment serving the alteration shall meet the applicable requirements of Sections 110.0 through 110.9, all applicable requirements of Sections 150.0(a) through (l), 150.0(m)1 through 150.0 (m)10, and 150.0(p) through (q); and A. Added fenestration. Alterations that add vertical fenestration and skylight area shall meet the total fenestration area and west facing fenestration area, U -factor, and solar heat gain coefficient requirements of Section 150.1(c)3A and Table 150.1-A.
Exception 1 to Section 150.2(b)1A: Alterations that increase fenestration area shall have a maximum SHGC value of 0.23 in Climate Zone 15.
Exception 2 to Section 150.2(b)1A: Alterations that add up to 16 square feet of new fenestration or skylight area shall not be required to meet the total fenestration area and west-facing fenestration area requirements of Sections 150.1(c)3B and C. B. Replacement fenestration. New manufactured fenestration products installed to replace existing fenestration products of the same total area shall meet the U-factor and Solar Heat Gain Coefficient requirements of Sections 150.1(c)3A, and 150.1(c)4.
CRC § 180.1 High relevance — show source text
The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered components’ energy features, plus the proposed energy features of the addition. Exception to Section 180.1(b)2: Existing structures with a minimum R-11 insulation in framed walls showing compliance with Section 180.1(b) are not required to show compliance with Section 160.1(b). 3. Mechanical ventilation for indoor air quality . Additions to existing buildings shall comply with Section 160.2 subject to the requirements specified in Subsections A and B below. When field verification and diagnostic testing are required by Section 180.1(b)3, buildings with three habitable stories or fewer shall use the applicable procedures in the Residential Appendices, and buildings with four or more habitable stories shall use the applicable procedures in Nonresidential Appendices NA1 and NA2.
272 2025 CALIFORNIA ENERGY CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS
A. Whole-dwelling unit mechanical ventilation . i. Dwelling units that meet the conditions in Subsection a or b below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 160.2(b)2Aiv or 160.2(b)2Av. a. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1000 square feet. b. Junior accessory dwelling units (JADU) that are additions to an existing building. ii. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by more than 1,000 square feet shall have mechanical ventilation airflow in accordance with Section 160.2(b)2Aiv or 160.2(b)2Av as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the entire dwelling unit comprising the existing dwelling unit conditioned floor area plus the addition conditioned floor area.
iii. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 160.2(b)2Aiv or 160.2(b)2Av as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. B. Local mechanical exhaust . Additions to existing buildings shall comply with all applicable requirements specified in Sections 160.2(b)2Avi and 160.2(b)2B.
NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .
SECTION 180.2—ALTERATIONS
Alterations to components of existing multifamily buildings, including alterations made in conjunction with a change in building occupancy to a multifamily occupancy, shall meet Item (a), and either Item (b) or (c) below:
CRC § 100.2 High relevance — show source text
SECTION 100.2—CALCULATION OF ENERGY BUDGETS
Energy budgets are adopted by the Commission to establish the maximum energy consumption that a proposed building, or portion of a building, can be designed to consume. A building complies with the performance standards compliance approach if the energy consumption calculated for the proposed design building is no greater than the energy budget calculated for the standard design building using Commission-certified compliance software as specified by the Alternative Calculation Methods Reference Manual. The energy budget for newly constructed single-family, multifamily, and nonresidential buildings are expressed in terms of Long-Term System Cost (LSC) and Source Energy. The energy budget for additions and alterations for all building types are expressed in terms of LSC.
Long-term System Cost (LSC) is calculated by multiplying for each hour of the year the site energy use (electricity kWh, natural gas therms, or fuel oil or LPG gallons) for each energy type by the applicable CEC-published LSC hourly factors. LSC hourly factors vary for each hour of the year and by energy type (electricity, natural gas, or propane), by Climate Zone and by building type (residential, nonresidential). LSC hourly factors are summarized in Reference Joint Appendix JA3. LSC hourly factors for propane are used for all energy obtained from depletable sources other than electricity and natural gas.
Source Energy is calculated by multiplying for each hour of the year the site energy use (electricity kWh, natural gas therms, or fuel oil or LPG gallons) by Btu factors for fossil fuel consumed either directly at the building site or caused to be consumed to meet the electrical demand of the building considering the long-term marginal hourly resources of Commission-projected electric system resource procurement.
Note: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .
36 2025 CALIFORNIA ENERGY CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ALL OCCUPANCIES—GENERAL PROVISIONS
FIGURE 100.1-A CALIFORNIA CLIMATE ZONES
Climate Zones for Residential and Nonresidential Occupancies
2025 CALIFORNIA ENERGY CODE 37
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
38 2025 CALIFORNIA ENERGY CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
2 ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE
MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS
SECTION 110.0—SYSTEMS AND EQUIPMENT—GENERAL
Sections 110.1 through 110.12 specify requirements for manufacturing, construction and installation of certain systems, equipment, appliances and building components that are installed in buildings within the scope of Section 100.0(a).
Note: The requirements of Sections 110.0 through 110.12 apply to newly constructed buildings. Sections 141.0 and 150.2 specify which requirements of Sections 110.1 through 110.12 also apply to additions and alterations to existing buildings.
CRC § 140.6 High relevance — show source text
140.6 Prescriptive Requirements for Indoor Lighting. . . .130
140.7 Prescriptive Requirements for Outdoor Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138
140.8 Prescriptive Requirements for Signs . . . . . . . . . . . . .141
140.9 Prescriptive Requirements for Covered
Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141
140.10 Prescriptive Requirements for Photovoltaic and Battery Energy Storage Systems . . . . . . . . . . . . . . .145
SUBCHAPTER 6 NONRESIDENTIAL AND
HOTEL/MOTEL OCCUPANCIES—ADDITIONS, ALTERATIONS
AND REPAIRS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
141.0 Additions, Alterations and Repairs to Existing Nonresidential and Hotel/Motel Buildings, to Existing Outdoor Lighting, and to Internally and Externally Illuminated Signs . . . . . . . . . . . . . . . . . . .149
141.1 Requirements for Covered Processes in Additions, Alterations to Existing Nonresidential and Hotel/Motel Buildings. . . . . . . . . . . . . . . . . . . . . . . . .157
SUBCHAPTER 7 SINGLE-FAMILY RESIDENTIAL BUILDINGS—
MANDATORY FEATURES AND DEVICES. . . . . . . . . . . . . . . 159
150.0 Mandatory Features and Devices. . . . . . . . . . . . . . . .159
2025 CALIFORNIA ENERGY CODE vii
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CONTENTS
SUBCHAPTER 8 SINGLE-FAMILY RESIDENTIAL BUILDINGS—
PERFORMANCE AND PRESCRIPTIVE COMPLIANCE
APPROACHES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
150.1 Performance and Prescriptive Compliance Approaches for Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
SUBCHAPTER 9 SINGLE-FAMILY
RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS
TO EXISTING RESIDENTIAL BUILDINGS . . . . . . . . . . . . . . 187
150.2 Energy Efficiency Standards for Additions and Alterations to Existing Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
SUBCHAPTER 10 MULTIFAMILY BUILDINGS—MANDATORY
REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
CRC § 170.1 High relevance — show source text
b. Either:
(i) Performance approach: Section 170.1; or (ii) Prescriptive approach: Section 170.2(a) through (f).
F. Covered processes.
i. Sections applicable. Sections 110.2, 120.3, 120.6, 140.9, and 141.1 apply to covered processes. ii. Compliance approaches. In order to comply with Part 6, covered processes must meet the requirements of: a. The applicable mandatory measures in Sections 110.2, 120.3 and 120.6; and
b. Either:
(i) The performance approach requirements of Section 140.1; or (ii) The prescriptive approach requirements of Section 140.9. 3. New construction in existing buildings (additions, alterations and repairs). A. Nonresidential and hotel/motel buildings. Section 141.0 applies to new construction in existing nonresidential, high-rise residential and hotel/motel buildings. New construction in existing buildings includes additions, alterations and repairs. Section 141.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specify which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 141.0 apply to the occupancy after the alterations. B. Single-family buildings. Section 150.2 applies to new construction in existing single-family buildings. New construction in existing buildings includes additions, alterations and repairs. Section 150.2 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specifies which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 150.2 apply to the occupancy after the alterations. C. Multifamily buildings. Section 180.0 applies to new construction in existing multifamily buildings. New construction in existing buildings includes additions, alterations and repairs. Section 180.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specifies which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 180.0 apply to the occupancy after the alterations. 4. Installation of insulation in existing buildings. Section 110.8(d) applies to buildings in which insulation is being installed in existing attics, or on existing water heaters or existing space conditioning ducts. 5. Outdoor lighting. Sections 110.9, 130.0, 130.2, 130.4, 140.7, and 150.0 apply to newly constructed outdoor lighting systems, and Section 141.0 applies to outdoor lighting that is either added or altered. 6. Signs. Sections 130.0, 130.3 and 140.8 apply to newly constructed signs located either indoors or outdoors, and Section 141.0 applies to sign alterations located either indoors or outdoors.
2025 CALIFORNIA ENERGY CODE 3
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ALL OCCUPANCIES—GENERAL PROVISIONS
(f) Mixed occupancy. When a building is designed and constructed for more than one type of occupancy (residential and nonresidential), the space for each occupancy shall meet the provisions of Part 6 applicable to that occupancy.
CRC § 301.3.2 High relevance — show source text
301.3.2 Work area compliance method. A lterations, additions and changes of occupancy complying with the applicable requirements of Chapters 6 through 12 of this code shall be considered in compliance with the provisions of this code.
301.3.3 Performance compliance method. Alterations, additions and changes of occupancy complying with Chapter 13 of this code shall be considered in compliance with the provisions of this code.
Note: [HCD 1 & HCD 2] The provisions contained in Chapter 13 are not adopted by HCD, but may be available for adoption by a local ordinance. (See Section 1.1.11.)
301.4 Relocated or moved buildings. Relocated or moved buildings shall comply with the requirements of Chapter 14.
SECTION 302—GENERAL PROVISIONS
302.1 Dangerous conditions. The code official shall have the authority to require the elimination of conditions deemed dangerous.
302.1.1 Dangerous conditions. [BSC] Regardless of the extent of structural or nonstructural damage, the code official shall have the authority to require the elimination of conditions deemed dangerous.
302.2 Additional codes. Alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall comply with the provisions for alterations, repairs, additions and changes of occupancy or relocation, respectively, in this code and the California Energy Code, California Fire Code, California Mechanical Code, California Plumbing Code, California Residential Code and California Electrical Code . Where provisions of the other codes conflict with provisions of this code, the provisions of this code shall take precedence.
302.2.1 Additional codes in health care. In existing Group I-2 occupancies, ambulatory health care facilities, outpatient clinics and hyperbaric facilities, alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall also comply with NFPA 99.
302.3 Existing materials. Materials already in use in a building in compliance with requirements or approvals in effect at the time of their erection or installation shall be permitted to remain in use unless determined by the code official to be unsafe.
302.4 New and replacement materials. Except as otherwise required or permitted by this code, materials permitted by the applicable code for new construction shall be used. Like materials shall be permitted for repairs and alterations, provided that unsafe conditions are not created. Hazardous materials shall not be used where the code for new construction would not permit their use in buildings of similar occupancy, purpose and location. [HCD 1] Local ordinances or regulations shall permit the replacement, retention and extension of original materials, and the use of original methods of construction, for any building or accessory structure, provided such building or structure complied with the building code provisions in effect at the time of original construction and the building or accessory structure does not become or continue to be a substandard building. For additional information, see Health and Safety Code Sections 17912, 17920.3, 17922(d), 17922.3, 17958.8 and 17958.9.
Exception: No replacement residential garage door shall be installed to connect the replacement door to an existing residential automatic garage door opener that does not have a battery backup function designed to keep the garage door operational without interruption during an electrical outage. See Health and Safety Code Section 19892.
CRC § 150.2 High relevance — show source text
For alterations that change the occupancy classification of the building, the requirements specified in Section 150.2 apply to the occupancy after the alterations. C. Multifamily buildings. Section 180.0 applies to new construction in existing multifamily buildings. New construction in existing buildings includes additions, alterations and repairs. Section 180.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specifies which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 180.0 apply to the occupancy after the alterations. 4. Installation of insulation in existing buildings. Section 110.8(d) applies to buildings in which insulation is being installed in existing attics, or on existing water heaters or existing space conditioning ducts. 5. Outdoor lighting. Sections 110.9, 130.0, 130.2, 130.4, 140.7, and 150.0 apply to newly constructed outdoor lighting systems, and Section 141.0 applies to outdoor lighting that is either added or altered. 6. Signs. Sections 130.0, 130.3 and 140.8 apply to newly constructed signs located either indoors or outdoors, and Section 141.0 applies to sign alterations located either indoors or outdoors.
2025 CALIFORNIA ENERGY CODE 3
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ALL OCCUPANCIES—GENERAL PROVISIONS
(f) Mixed occupancy. When a building is designed and constructed for more than one type of occupancy (residential and nonresidential), the space for each occupancy shall meet the provisions of Part 6 applicable to that occupancy.
Exception 1 to Section 100.0(f): If one occupancy constitutes at least 80 percent of the conditioned floor area of the building, the entire building envelope, HVAC and water heating may be designed to comply with the provisions of Part 6 applicable to that occupancy, provided that the applicable lighting requirements in Sections 140.6 through 140.8, 150.0(k), or 160.5 and 170.2(e) are met for each occupancy and space, and mandatory measures in Sections 110.0 through 130.5, 150.0, and 160.0 through 160.9 are met for each occupancy and space.
Exception 2 to Section 100.0(f): If one occupancy constitutes at least 90 percent of the combined conditioned plus unconditioned floor area of the building, the entire building indoor lighting may be designed to comply with only the lighting provisions of Part 6 applicable to that occupancy.
(g) Administrative requirements. Administrative requirements relating to permit requirements, enforcement by the Commission, locally adopted energy standards, interpretations, claims of exemption, approved calculation methods, rights of appeal, and certification and labeling requirements of fenestration products and roofing products are specified in California Code of Regulations, Title 24, Part 1, Sections 10-101 to 10-114.
(h) Certification requirements for manufactured equipment, products and devices. Part 6 limits the installation of manufactured equipment, products and devices to those that have been certified as specified by Sections 110.0 and 110.1. Requirements for manufactured equipment, products, and devices, when not specified in Title 24 Part 6, are specified in California Code of Regulations, Title 20, Sections 1601–1609.
CRC § 120.0 High relevance — show source text
2 2025 CALIFORNIA ENERGY CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ALL OCCUPANCIES—GENERAL PROVISIONS
ii. Compliance approaches. In order to comply with Part 6, newly constructed nonresidential buildings and hotels/motels that are mechanically heated or mechanically cooled must meet the requirements of: a. Mandatory measures: The applicable provisions of Sections 120.0 through 130.5; and
b. Either:
(i) Performance approach: Section 140.1; or (ii) Prescriptive approach: Sections 140.2 through 140.10. C. Unconditioned nonresidential buildings and process space. Sections 110.9, 110.10, 120.6, 130.0 through 130.5, 140.3(c), 140.6, 140.7 and 140.8 apply to all newly constructed unconditioned buildings and for process spaces within the scope of Section 100.0(a). D. Single-family buildings. i. Sections applicable. Sections 150.0 through 150.1 apply to newly constructed single-family buildings. ii. Compliance approaches. In order to comply with Part 6, newly constructed single-family buildings must meet the requirements of: a. Mandatory measures: The applicable provisions of Sections 110.0 through 110.10 and 150.0; and
b. Either:
(i) Performance approach: Sections 150.1(a) and (b); or (ii) Prescriptive approach: Sections 150.1(a) and (c). Exception to Section 100.0(e)2Diib: Seasonally occupied agricultural housing limited by state or federal agency contract to occupancy not more than 180 days in any calendar year. E. Multifamily Buildings . i. Sections applicable. Sections 160.0 through 170.2 apply to newly constructed multifamily buildings. ii. Compliance approaches. In order to comply with Part 6, newly constructed multifamily buildings must meet the requirements of: a. Mandatory measures: The applicable provisions of Sections 110.0 through 110.10, and 160.0; and
b. Either:
(i) Performance approach: Section 170.1; or (ii) Prescriptive approach: Section 170.2(a) through (f).
F. Covered processes.
i. Sections applicable. Sections 110.2, 120.3, 120.6, 140.9, and 141.1 apply to covered processes. ii. Compliance approaches. In order to comply with Part 6, covered processes must meet the requirements of: a. The applicable mandatory measures in Sections 110.2, 120.3 and 120.6; and
b. Either:
(i) The performance approach requirements of Section 140.1; or (ii) The prescriptive approach requirements of Section 140.9. 3. New construction in existing buildings (additions, alterations and repairs). A. Nonresidential and hotel/motel buildings. Section 141.0 applies to new construction in existing nonresidential, high-rise residential and hotel/motel buildings. New construction in existing buildings includes additions, alterations and repairs. Section 141.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specify which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 141.0 apply to the occupancy after the alterations. B. **Single-family buildings.
CRC § 1.10.1 Medium 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.
2025 CALIFORNIA EXISTING BUILDING CODE xiii
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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.
Frequently asked questions
When does an addition have to meet photovoltaic (PV) requirements?
Photovoltaic and certain battery requirements that apply to new construction are generally not required for additions under the residential additions rules (see the exception in §150.2(a): “Photovoltaic systems … are not required for additions”) . Check the specific size and scope exceptions in §150.2 for limits that may affect your project.
If I replace or alter a component, must it meet new‑construction requirements?
Altered components are treated explicitly: compliance may be met either by following the prescriptive requirements for the altered component or by including the altered component in the performance energy‑budget model where the standard design uses the existing unaltered components plus the altered components set to the more‑efficient of existing conditions or the applicable requirement. See the “existing plus alteration plus addition” rules described for additions and alterations .
Are there size thresholds or small‑work exceptions?
Yes. The code includes several size‑based exceptions (for example, small roofing or small fenestration changes and thresholds for ventilation and other measures). Examples include limited roofing exceptions for very small additions and ventilation thresholds tied to increases in conditioned floor area; review the exceptions listed in §150.2 for the exact thresholds that may apply to your project .
More in California Residential Code
Ask about the CRC
Get cited, plain-English answers on the California Residential Code for your project — any code section, any scenario.
Start Free Trial