CRC · California Residential Code
Existing Building Code — Additions and energy conservation (1104.1)
If you’re adding on to a house in California, **§ 1104.1** requires that the addition follow the California Energy Code (Title 24, Part 6). That means check Part 6 (not just the CRC text) for insulation, window, HVAC and small‑addition exceptions (e.g., ≤300 sq ft roofing exception, >700 sq ft prescriptive triggers). Document which Part 6 sections and any exceptions apply when you submit your permit.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
Additions to existing buildings in California must follow the energy rules in the California Energy Code (Title 24, Part 6). In short, any addition is required to comply with the applicable provisions of the California Energy Code — this requirement is stated in § 1104.1 of the California Existing Building Code.
The single most important rule: if you are doing an addition, treat the work as subject to Title 24, Part 6 (the California Energy Code) unless a specific exception in Part 6 applies.
Requirements in detail
Summary: § 1104.1 does not re-write the energy rules — it points the project to the California Energy Code (Part 6, Title 24, C.C.R.). That means the specific energy thresholds, insulation, fenestration, HVAC and duct requirements, and the exceptions for small additions are found in the Energy Code (for example, Section § 150.2 for single‑family additions). You must read Part 6 to determine which provisions apply to your specific addition.
How to use § 1104.1 on a project
- Determine whether the work is an addition (scope, area, vertical or horizontal) under the Existing Building Code definitions and your local building official’s interpretation. Addition is the defined project type that triggers § 1104.1.
- Apply the applicable Part 6 (Title 24) requirements for that building type and for the specific work (prescriptive or performance compliance paths in the Energy Code). See Section § 150.2 of the California Energy Code for energy-efficiency standards for additions and alterations to existing single‑family residential buildings.
- Where the Energy Code contains exceptions (small additions, duct extension rules, PV exceptions, etc.), those exceptions govern whether particular Part 6 provisions are required.
Decision-relevant thresholds and rules (quick table)
| Decision question | Key value / threshold | What that triggers | Code Reference |
|---|---|---|---|
| Small roofing exception for single‑family additions | ≤ 300 sq ft | Roofing requirements of § 150.1(c) not required for the addition | California Energy Code, § 150.2 (Exception 1) |
| Prescriptive requirements threshold for additions | > 700 sq ft | Addition must meet § 150.1(c) (with specified insulation and fenestration rules) — see modifications for wall framing and maximum fenestration | California Energy Code, § 150.2 (Prescriptive approach A) |
| Ventilation cooling exemption | ≤ 1,000 sq ft | Additions 1,000 sq ft or less are not required to comply with certain ventilation cooling requirements | California Energy Code, § 150.2 (Exception 5) |
| Photovoltaic requirement for additions | — | PV systems required elsewhere in Part 6 are not required for additions (see exception) | California Energy Code, § 150.2 (Exception 6) |
| Space-conditioning equipment extension | — | If HVAC is extended from existing equipment, the existing equipment need not be replaced to meet Part 6, provided capacity meets CRC § 303.10 minimums | California Energy Code, § 150.2 (Exception 3); CRC reference to heating capacity: § 303.10 |
Notes:
- The table above extracts the most commonly used numeric thresholds and the specific Energy Code pointers. The controlling requirement in the Existing Building Code remains § 1104.1 which mandates compliance with Part 6.
- The Energy Code contains additional detailed provisions (duct testing/insulation, wall cavity R‑values, glazing U‑factors/SHGC limits, etc.) that must be read and applied to the project documentation.
Prescriptive items frequently triggered by additions
- Insulation: Additions that increase conditioned space normally must meet prescriptive insulation requirements (for example, cavity insulation R‑15 in 2×4 walls or R‑21 in 2×6 walls when extending wood‑framed walls).
- Fenestration area limits: For additions subject to the prescriptive path, the Energy Code caps maximum fenestration as the greater of 175 sq ft or 20% of the addition floor area (with specific limits for west‑facing glazing).
- Duct and HVAC rules: When ducts are extended to serve an addition, both the extension and the existing duct system must meet the Energy Code’s duct requirements (insulation, sealing, testing) unless a stated exception applies.
Exceptions & special cases
- The Existing Building Code text of § 1104.1 is a pointer to the Energy Code; it does not itself create special exceptions beyond what Part 6 contains. Apply the exceptions that are specifically listed in the California Energy Code (for example, the small‑addition roofing exception, HVAC extension exceptions, and the PV exception).
- Historic buildings: Chapter 12 of the Existing Building Code (not adopted in California) and Part 8 of Title 24 govern historic structures. If your building is designated historic, other parts of Title 24 (Part 8) may control energy exceptions; check local authority guidance.
- Local amendments: Cities/counties may adopt energy-related ordinances but they must be consistent with California Energy Commission rules; verify whether a local jurisdiction has an approved local energy ordinance that alters Part 6 applicability.
Common mistakes
- Assuming § 1104.1 is an “opt‑out”: some practitioners read § 1104.1 as optional. It is not — it requires that additions comply with the Energy Code. Always check Part 6.
- Overlooking Part 6 exceptions: many small additions qualify for specific exceptions (for example ≤ 300 sq ft for some roofing requirements); failing to apply those exceptions can lead to unnecessary scope and permit delays.
- Mixing CRC prescriptive residential rules with Title 24 without reconciling them: the CRC explains that Parts IV–VIII of the IRC are replaced by Title 24 in California — do not rely on IRC Chapter 11 prescriptive language without checking Part 6.
- Forgetting HVAC capacity requirements when extending heating/cooling: Exception 3 in § 150.2 allows keeping existing equipment only if capacity meets the CRC minimums (see § 303.10). Always document capacity compliance.
Worked example — applying § 1104.1 with numbers
Scenario: A homeowner plans a horizontal addition of 800 sq ft of conditioned living area to an existing single‑family home. The work will extend existing wood‑framed walls and connect the existing HVAC system.
Steps and how the rules apply:
- Control rule: Because this is an addition, § 1104.1 requires the addition to comply with the California Energy Code (Part 6).
- Under the Energy Code, § 150.2 prescriptive approach applies to additions; because the addition is > 700 sq ft, the project must meet the requirements of § 150.1(c) with the specific modifications listed in § 150.2 (prescriptive approach). That includes wall cavity insulation rules and fenestration limits.
- Wall insulation: if the project extends existing wood‑framed walls, the designer may retain existing wall dimensions but must install cavity insulation of R‑15 for 2×4 framing or R‑21 for 2×6 framing, per the Energy Code modification.
- Fenestration: maximum allowed fenestration for the addition is the greater of 175 sq ft or 20% of the addition floor area; for an 800 sq ft addition, 20% = 160 sq ft, so the allowed maximum is 175 sq ft. West‑facing glazing may have additional limits.
- HVAC: The homeowner plans to extend the existing HVAC to serve the new area. Under the Energy Code Exception 3 to § 150.2(a), the existing heating/cooling equipment does not have to be replaced to meet Part 6 provided its capacity is adequate to meet the CRC minimums (see § 303.10). Document the existing equipment capacity and verify it meets CRC § 303.10 minimum capacity for the combined conditioned area.
- PV and ventilation: The addition size (800 sq ft) is not exempt from all measures, but the Energy Code explicitly states that photovoltaic systems are not required for additions (Exception 6), and additions ≤ 1,000 sq ft may be exempt from certain ventilation cooling requirements (Exception 5). Confirm which specific measures apply in your climate zone and documentation.
Result: The permit package for this 800‑sq‑ft addition must show compliance with the applicable Part 6 prescriptive details (insulation, glazing, ducting) per the instructions above and reference § 1104.1 as the Existing Building Code requirement that mandates Part 6 compliance.
Related provisions
- § 1101 (Additions — General) — Chapter 11 introductory provisions on additions.
- § 1102 (Heights and Areas) — size/area related rules for additions.
- § 1103 (Structural) — structural requirements that can interact with energy upgrades when additions change loads or framing.
- § 1104.1 (Energy Conservation) — the controlling Existing Building Code requirement: additions must comply with the California Energy Code (Part 6).
- § 150.2 (California Energy Code) — Energy efficiency standards for additions and alterations to existing single‑family residential buildings (prescriptive thresholds and exceptions).
- § 150.1(c) (California Energy Code) — referenced by § 150.2 for prescriptive measures (insulation, fenestration, etc.).
- § 303.10 (CRC) — minimum heating system capacity referenced in Energy Code exceptions when existing HVAC is extended.
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 1104.1 High relevance — show source text
- 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).
11-4 2025 CALIFORNIA EXISTING BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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.
2025 CALIFORNIA EXISTING BUILDING CODE 12-1
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12-2 2025 CALIFORNIA EXISTING BUILDING CODE
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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.)
Adopting Agency BSC BSC-
CGSFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC Adopting Agency BSC BSC-
CGSFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6 Adopt Entire Chapter Adopt Entire Chapter as
amended (amended
sections listed below)Adopt only those sections
that are listed belowChapter / Section 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.
2025 CALIFORNIA EXISTING BUILDING CODE 13-1
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13-2 2025 CALIFORNIA EXISTING BUILDING CODE
CRC § 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).
11-4 2025 CALIFORNIA EXISTING BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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.
2025 CALIFORNIA EXISTING BUILDING CODE 12-1
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
12-2 2025 CALIFORNIA EXISTING BUILDING CODE
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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.)
CRC § 10-3 High relevance — show source text
1003 Building Elements and Materials . . . . . . . . . . . . . . . . 10-3
1004 Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
1005 Means of Egress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
1006 Structural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
1007 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4
1008 Mechanical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4
1009 Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4
1010 Other Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5
1011 Change of Occupancy Classification . . . . . . . . . . . . . 10-5
CHAPTER 11 ADDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3
1101 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3
1102 Heights and Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3
1103 Structural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4
1104 Energy Conservation. . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4
CHAPTER 12 HISTORIC BUILDINGS . . . . . . . . . . . . . . . . . .12-1
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CHAPTER 13 PERFORMANCE COMPLIANCE METHODS. . 13-3
1301 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3
1302 Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3
1303 Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-4
CRC § 25218.5 Medium relevance — show source text
Note: Authority: Sections 25213, 25218, 25218.5, 25402, 25402.1, and 25605, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8, 25605, and 25943, Public Resources Code.
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9 SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND
ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS
SECTION 150.2—ENERGY EFFICIENCY STANDARDS FOR ADDITIONS AND
ALTERATIONS TO EXISTING SINGLE-FAMILY RESIDENTIAL BUILDINGS
(a) Additions. Additions to existing single-family residential buildings shall meet the requirements of Sections 110.0 through 110.9; Sections 150.0(a) through (n), (p) and (q); and either Section 150.2(a)1 or 2.
Exception 1 to Section 150.2(a): Additions of 300 square feet or less are not required to comply with the roofing requirements of Section 150.1(c)11.
Exception 2 to Section 150.2(a): Existing inaccessible piping shall not require insulation as defined under Section 150.0(j)1.
Exception 3 to Section 150.2(a): Space-conditioning system. When heating or cooling will be extended to an addition from the existing system(s), the existing heating and cooling equipment need not comply with Part 6. The heating system capacity must be adequate to meet the minimum requirements of CRC 303.10.
Exception 4 to Section 150.2(a): Space-conditioning system ducts. When any length of duct is extended from an existing duct system to serve the addition, the existing duct system and the extended duct shall meet the applicable requirements specified in Section 150.2(b)1Di and 150.2(b)1Dii.
Exception 5 to Section 150.2(a): Additions 1,000 square feet or less are not required to comply with the ventilation cooling requirements of Section 150.1(c)12.
Exception 6 to Section 150.2(a): Photovoltaic systems, as specified in Section 150.1(c)14, are not required for additions.
- Prescriptive approach. Additions to existing buildings shall meet the following additional requirements: A. Additions that are greater than 700 square feet shall meet the requirements of Section 150.1(c), with the following modifications:
i. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and shall install cavity insulation of R-15 in a 2 × 4 framing and R-21 in a 2 × 6 framing. ii. The maximum allowed fenestration area shall be the greater of 175 square feet or 20 percent of the addition floor area, and the maximum allowed west-facing fenestration area shall be the greater of 70 square feet or the requirements of Section 150.1(c).
CRC § 6-3 Medium relevance — show source text
601 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
602 Alteration—Level 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
603 Alteration—Level 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
604 Alteration—Level 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
605 Change of Occupancy. . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
606 Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
607 Historic Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
CHAPTER 7 ALTERATIONS—LEVEL 1 . . . . . . . . . . . . . . . . . .7-3
701 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
702 Building Elements and Materials . . . . . . . . . . . . . . . . . 7-3
703 Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
704 Means of Egress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
705 Reroofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
706 Structural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
707 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
708 Energy Conservation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
CHAPTER 8 ALTERATIONS—LEVEL 2 . . . . . . . . . . . . . . . . . .8-3
801 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
802 Building Elements and Materials . . . . . . . . . . . . . . . . . 8-3
CRC § 11-3 Medium relevance — show source text
1101 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3
1102 Heights and Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3
1103 Structural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4
1104 Energy Conservation. . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4
CHAPTER 12 HISTORIC BUILDINGS . . . . . . . . . . . . . . . . . .12-1
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CHAPTER 13 PERFORMANCE COMPLIANCE METHODS. . 13-3
1301 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3
1302 Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3
1303 Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-4
1304 Investigation and Evaluation . . . . . . . . . . . . . . . . . . . 13-4
1305 Scoring and Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 13-4
1306 Building Score . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-14
1307 Evaluation of Building Safety. . . . . . . . . . . . . . . . . . 13-16
CHAPTER 14 RELOCATED OR MOVED BUILDINGS . . . . . . 14-3
1401 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-3
1402 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-3
CHAPTER 15 CONSTRUCTION SAFEGUARDS . . . . . . . . . . 15-3
1501 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-3
1502 Owner’s Responsibility for Fire Protection . . . . . . . 15-3
1503 Sanitary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-4
California Residential Code Medium relevance — show source text
3/8″
main reinforcement bars at 57/8″ pitch
with7/8″ concrete cover;3/8″ main rein-
forcement bars at 41/2″ pitch
perpendicular with1/2″ concrete cover;
13′1″ span restrained.|195 psf|4 hrs|||7|1, 7|4| |F/C-4-RC-7|4″|4″ (5025 psi) concrete deck;1/4″ reinforce-
ment bars at 71/2″ pitch with3/4″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|1 hr
16 min|||7|1, 2|11/4| |F/C-4-RC-8|4″|4″ thick (4905 psi) deck;1/4″ reinforce-
ment bars at 71/2″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|100 psf|1 hr
23 min|||7|1, 2|11/3| |F/C-4-RC-9|4″|4″ deep (4370 psi);1/4″ reinforcement bars
at 6″ pitch with3/4″ cover;1/4″ main rein-
forcement bars at 4″ pitch perpendicular
with1/2″ cover; 13′1″ span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-10|4″|4″ thick (5140 psi) deck;1/4″ reinforce-
ment bars at 71/2″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|1 hr
16 min|||7|1, 5|11/4| |F/C-4-RC-11|4″|4″ thick (4000 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom of slab; 6′6″
span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-12|4″|4″ deep (2380 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.CRC § 301 Medium relevance — show source text
This change expands the current process from two independent 1-year cycles to a single continuous 3year cycle. There will be two groups of code development committees and they will meet in separate years. The current groups will be reworked. With the energy provisions of the International Energy Conservation Code ® (IECC®) and Chapter 11 of the International Residential Code ® (IRC®) now moved to the Code Council’s Standards Development Process, the reduced volume of code changes will be distributed between Groups A and B.
Code change proposals submitted for code sections that have a letter designation in front of them will be heard by the respective committee responsible for such code sections. Because different committees hold Committee Action Hearings in different years, proposals for most codes will be heard by committees in both the 2024 (Group A) and the 2025 (Group B) code development cycles. It is very important that anyone submitting code change proposals understands which code development committee is responsible for the section of the code that is the subject of the code change proposal.
Please visit the ICC website at iccsafe.org/products-and-services/i-codes/code-development/current-code-development-cycle for further information on the Code Development Committee responsibilities as it becomes available.
Coordination of the I-Codes
The coordination of technical provisions allows the I-Codes to be used as a complete set of complementary documents. Individual codes can also be used in subsets or as stand-alone documents. Some technical provisions that are relevant to more than one subject area are duplicated in multiple model codes.
INTRODUCTION TO THE INTERNATIONAL EXISTING BUILDING CODE
The IEBC establishes minimum requirements for existing buildings using prescriptive and performance-related provisions. It is founded on broad-based principles intended to encourage the use and reuse of existing buildings while requiring reasonable upgrades and improvements.
The IEBC is a model code in the International Code family of codes intended to provide requirements for repair and alternative approaches for alterations, changes of occupancy and additions to existing buildings. A large number of existing buildings and structures do not comply with the current building code requirements for new construction. Although many of these buildings are potentially salvageable, rehabilitation is often cost-prohibitive because compliance with all the requirements for new construction could require extensive changes that go well beyond the value of the building or the original scope of the alteration. At the same time, it is necessary to regulate construction in existing buildings that undergo additions, alterations, extensive repairs or change of occupancy. Such activity represents an opportunity to ensure that new construction complies with the current building codes and that existing conditions are maintained, at a minimum, to their current level of compliance or are improved as required to meet basic safety levels. To accomplish this objective, and to make the alteration process easier, this code allows for options for controlled departure from full compliance with the International Codes dealing with new construction, while maintaining basic levels for fire safety, structural and life safety features of the rehabilitated building.
This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:
Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).
Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area C
CRC § 25402.1 Medium relevance — show source text
- The city, county, or city and county shall obtain California Energy Commission approval for any energy- related ordinances consistent with Public Resources Code Section 25402.1(h)(2) and Title 24, Part 1, Section 10-106. Local governmental agencies may adopt and enforce energy standards for newly constructed buildings, additions, alterations and repairs, provided the California Energy Commission finds that the standards will require buildings to be designed to consume no more energy than permitted by Part 6. Such local standards include, but are not limited to, adopting the requirements of Part 6 before their effective date, requiring additional energy conservation measures, or setting more stringent energy budgets.
101.8 Alternate materials, designs and methods of construction. The provisions of this code are not intended to prevent the use of any alternate material, appliance, installation, device, arrangement, method, design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternate shall be approved on a case-by-case basis where the enforcing agency finds that the proposed alternate is satisfactory and complies with the intent of the provisions of this code and is at least the equivalent of that prescribed in this code in planning and design, energy, water, material conservation and resource efficiency, environmental air quality, performance, safety and the protection of life and health. Consideration and compliance provisions for occupancies regulated by adopting state agencies are found in the sections listed below.
- Section 1.2.3 in the California Building Code (CBC) for the California Building Standards Commission.
- Section 104.2.3 in the California Building Code (CBC) for the Division of the State Architect.
- Section 1.8.7 in the California Building Code (CBC); and Section 1.8.7 in the California Residential Code (CRC) for the Department of Housing and Community Development.
- Section 7-104 in the California Administrative Code for the Office of the Statewide Health Planning and Development.
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ADMINISTRATION
101.9 Effective date of this code. Only those standards approved by the California Building Standards Commission that are effective at the time an application for a building permit is submitted shall apply to the plans and specifications for, and to the construction performed under, that permit. For the effective dates of the provisions contained in this code, see the appropriate application checklist and the History Note page of this code.
101.10 Mandatory requirements. This code contains both mandatory and voluntary green building measures. Mandatory and voluntary measures are identified in the appropriate application checklist contained in this code.
101.11 Effective use of this code. The following steps shall be used to establish which provisions of this code are applicable to a specific occupancy:
- Establish the type of occupancy.
- Verify which state agency has authority for the established occupancy by reviewing the authorities list in Sections 103 through 106.
- Once the appropriate agency has been identified, find the chapter which covers the established occupancy.
- The Matrix Adoption Tables at the beginning of Chapters 4 and 5 identify the mandatory green building measures necessary to meet the minimum requirements of this code for the established occupancy.
- Voluntary tier measures are contained in Appendix Chapters A4 and A5. A checklist containing each green building measure, both required and voluntary, is provided at the end of each appendix chapter.
CRC § 170.2 Medium relevance — show source text
The rated energy capacity shall be not less than the Minimum Rated Useable Energy Capacity determined by Equation 170.2-E, or by Equation 170.2-F if SARA was used to determine the PV capacity in Section 170.2-D, and the rated power capacity shall be not less than the Minimum Power Capacity determined by Equation 170.2-G. In mixed occupancy buildings, the total battery system capacity for the building shall be determined by applying the Minimum Rated Usable Energy Capacity to each of the listed building types and summing the capacities determined for each.
EQUATION 170.2-E—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY kWh batt = k((CFA × B)/(1000 × C [0.5] ))
— EQUATION 170.2-F BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY, SARA-ADJUSTED kWh batt = k((CFA × B)/(1000 × C [0.5] )) × (kWP Vdc,SARA /kWP Vdc )
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MULTIFAMILY BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES
where:
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
kW PVdc = Minimum Rated PV System Capacity in kW from Equation 170.2D. kW PVdc, SARA = Minimum Rated PV System Capacity in kW from the SARA calculation. CFA = Conditioned floor area that is subject to the PV system requirements of Section 170.2(g) in square feet.
B = BESS Capacity Factor in Wh/square foot as specified in Table 170.2-V for the building type.
C = Rated single charge-discharge cycle AC to AC (round-trip) efficiency of the BESS.
EQUATION 170.2-G—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED POWER CAPACITY
kW batt = kW batt /4
where:
kW batt = Minimum Rated Power Capacity of the BESS in kW dc .
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
Exception 1 to Section 170.2(h): No BESS is required if the installed PV system capacity is less than 15 percent of the capacity determined by Equation 170.2-D.
Exception 2 to Section 170.2(h): No BESS is required in buildings with BESS requirements with less than 10 kWh minimum rated usable energy capacity.
|TABLE 170.
CRC § 5.409.3 Medium relevance — show source text
1,5.409.3,
5.409.3.1, 5.409.3.2
and Table 5.409.3||||| |(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|Tier 2
Prerequisite|Enhanced construction waste reduction (80%—Tier 2
with verification)|A5.408.3.1.1,
A5.408.3.1.2||||| |(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|Mandatory|Recycling by occupants (with exception)|5.410.1||||| |(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|Mandatory|Recycling by occupants: additions (with exception)|5.410.1.1||||| |(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|Mandatory|Recycling by occupants: sample ordinance
|5.410.1.2||||| |(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|Mandatory|Commissioning new buildings (³10,000 sf) [N]|5.410.2||||| |(continued)
DIVISION 5.4
Material
Conservation
and Resource
Efficiency
Select Three Electives
(cont’d)|(continued)
**DIVISION 5.CRC § 5.106.5.3.6 Medium relevance — show source text
Table 5.106.5.3.6,
5.106.5.3.6.1,
5.106.5.3.6.2 and
5.106.5.3.6.3||||| |DIVISION 5.1
Planning and
Design|Mandatory|Additions or Alterations to existing buildings or parking facili-
ties [A] with Exceptions|5.106.5.4||||| |DIVISION 5.1
Planning and
Design|Mandatory|Existing buildings or parking areas without previously
installed EV capable infrastructure [A]|5.106.5.4.1||||| |DIVISION 5.1
Planning and
Design|Mandatory|Existing buildings or parking areas without previously
installed EV capable infrastructure [A]|5.106.5.4.2||||| |DIVISION 5.1
Planning and
Design|Mandatory|Electric vehicle (EV) charging: medium-duty and heavy-duty [N]|5.106.5.5||||| |DIVISION 5.1
Planning and
Design|Mandatory|Electric vehicle charging readiness requirements for warehouses,
grocery stores and retail stores, office buildings, and manufactur-
ing facilities with planned off-street loading spaces [N]|5.106.5.5.1||||| |DIVISION 5.1
Planning and
Design|Mandatory|Table 5.106.5.5.1|5.106.5.5 and
5.106.5.5.1||||| |DIVISION 5.1
Planning and
Design|Mandatory|Light pollution reduction [N] (with exceptions, notes and table)|5.106.8 through
5.106.8.2||||| |DIVISION 5.1
Planning and
Design|Mandatory|Grading and paving (exception for additions and alterations
not altering the drainage path)|5.106.10||||| |DIVISION 5.2
Energy
Efficiency|Mandatory|Meet the minimum energy efficiency standard|5.201.1|||||APPENDIX A5-44 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE
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APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES
CHAPTER 5
DIVISIONSCol2 SECTION TITLE CODE
SECTIONY N/A O PLAN SHEET,
SPEC OR
ATTACHDIVISION 5.3
Water
Efficiency and
ConservationMandatory Separate meters (new buildings or additions > 50,000 sf
that consume more than 100 gal/day)5.303.1.1 **DIVISION 5.
Frequently asked questions
Do I always need to replace my HVAC if I extend it to an addition?
No. Per the Energy Code exception cited by § 150.2, existing heating/cooling equipment need not be replaced when extended to serve an addition provided the equipment capacity is adequate to meet CRC § 303.10 minimums; you must document capacity.
Are very small additions exempt from Energy Code requirements?
Not entirely — but there are targeted exceptions (for example, ≤ 300 sq ft for some roofing rules). The overarching requirement in § 1104.1 is that additions comply with applicable portions of Part 6; check the specific exceptions in § 150.2.
Does § 1104.1 itself spell out insulation and glazing values?
No. § 1104.1 directs you to the California Energy Code (Part 6). Specific insulation R‑values, glazing limits, and other numeric requirements are in Part 6 (for example, § 150.1(c) and § 150.2).
If my building is historic, do I still follow § 1104.1?
Historic buildings are treated separately; Chapter 12 of the Existing Building Code and Part 8 of Title 24 address historic structures. Confirm historic‑building applicability with the AHJ.
Where do I find the detailed energy compliance checks I must document?
Follow the applicable Part 6 sections (notably § 150.2 for additions/alterations to single‑family residences, and the referenced prescriptive sections such as § 150.1(c)). Your permit submittal should include the Energy Code forms, calculations, and any exceptions relied upon.
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