Title 24 · California Energy Code

Mandatory air leakage sealing and requirements to limit air leakage

Q: Do I need to perform an airtightness test (blower door) because of § 110.7?

No — § 110.7 itself mandates that openings be sealed but does not require a whole‑building airtightness (blower door) test. Quantitative testing requirements (and where they apply) are specified in other Code sections and reference appendices. See § 160.3 , § 150.2 , § 180.2 for testing and duct leakage rules.

Q: Does § 110.7 tell me which sealant product to use?

No — § 110.7 prescribes the methods (caulk, gasket, weather‑strip, or otherwise sealed) but does not specify brands or product test standards; follow manufacturer instructions and any applicable material/assembly standards referenced elsewhere in the Code.

Q: Are ducts covered by § 110.7?

Ducts are related but treated separately. § 110.7 addresses envelope openings; duct sealing, leakage limits, and test procedures are in sections like § 160.3 , § 150.2 , and § 180.2 . Meet both the envelope sealing requirement and the specific duct sealing/testing requirements where applicable.

Q: If I seal accessible leaks but not concealed ones, am I compliant?

§ 110.7 requires sealing of all potential leak sources. Concealed leaks that remain unsealed but were accessible during construction could be cited by the enforcing authority; document attempts to seal and explain inaccessible conditions to the inspector. The Code text is general — enforcement interprets whether a particular leak was reasonably sealable.

As a homeowner: California’s Energy Code (Section 110.7) requires that any gap or penetration in your building’s exterior that can leak air be sealed with caulk, gaskets, weatherstripping, or equivalent so warm or cool air stays inside; the section mandates sealing but leaves specific testing and numeric leakage limits to other Code sections.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Energy Code requires that all joints, penetrations, and other openings in the building envelope that could leak air be caulked, gasketed, weather‑stripped, or otherwise sealed to limit infiltration and exfiltration — this is the mandatory rule in § 110.7. § 110.7 is short and prescriptive: it mandates sealing (the “what” and the “how” at a high level) but does not list test thresholds or prescriptive material standards in that single paragraph.

Seal every potential air‑leak path in the building envelope — if it can leak air, it must be caulked, gasketed, weather‑stripped, or otherwise sealed (see § 110.7).

Requirements in detail

Primary obligation (plain code)

Who: All projects subject to the California Energy Code.
What: All joints, penetrations, and other openings in the building envelope that are potential sources of air leakage.
How: Must be caulked, gasketed, weather‑stripped, or otherwise sealed.
Why: To limit infiltration and exfiltration of conditioned air. § 110.7.

Decision‑relevant summary table

Decision dimension	Key value / action	Code reference
What to treat	All joints, penetrations, and other openings in the building envelope	§ 110.7.
Acceptable methods	Caulking, gasketing, weather‑stripping, otherwise sealed	§ 110.7.
Purpose / performance goal	Limit infiltration and exfiltration (general performance objective)	§ 110.7.
Material/specification details	Not specified in § 110.7; use manufacturer specs and applicable material standards or other code sections when required	§ 110.7 (note: no material specs in text).
Testing / verification	§ 110.7 mandates sealing but does not prescribe leakage test thresholds; separate sections (e.g., duct sealing/testing) contain quantitative leakage targets and test procedures. See § 150.2, § 160.3, § 180.2 for related sealing/testing requirements.

Practical implications (what this actually requires on a job)

You must identify any potential air‑leak location in the envelope and apply an approved sealing method (caulk, gasket, weatherstrip, etc.). § 110.7 is not a performance test — it is a mandatory installation requirement.
Where the Code elsewhere sets quantitative leakage limits and test procedures (for example, ducts and altered systems), follow those sections in addition to the general sealing requirement. See the duct sealing and leakage testing rules in § 160.3 and in the residential chapters such as § 150.2 and § 180.2.

Exceptions & special cases

§ 110.7 itself contains no listed exceptions or special exemptions in the text recovered; it is a blanket mandatory requirement to seal potential leakage points.
Special, quantified leakage rules and the exceptions that apply to duct systems (for example, measured leakage limits, altered‑system provisions, and exceptions for asbestos, short duct runs, or multifamily stories) appear in other sections such as § 150.2, § 160.3, and § 180.2. When your work involves ducts or altered HVAC systems, follow those sections for testing thresholds and any exceptions.
If you need a material standard or testing requirement for a particular assembly (for example, damper leakage tested to an AMCA standard), consult the relevant sections and referenced standards elsewhere in the Code.

Common mistakes

Assuming sealing of the envelope is optional because there’s no leakage number in § 110.7 — incorrect. § 110.7 is mandatory even though it’s short on numeric thresholds.
Confusing envelope sealing with duct leakage requirements — ducts have separate, quantitative sealing and testing rules in § 160.3, § 150.2, § 180.2 and related Reference Appendices. Don’t rely on § 110.7 to satisfy duct leakage tests.
Using inappropriate materials (e.g., ordinary tape that fails in weather) where durable caulks, gaskets, or weatherstripping are required. § 110.7 requires sealing but leaves material selection to good practice and applicable product standards — check manufacturer instructions and referenced standards.
Overlooking small or concealed penetrations (service lines, flashing terminations, gaps at framing, etc.). The text covers “all joints, penetrations and other openings” — look broadly.

Worked example — concrete scenario applying the rule with numbers

Scenario (example): A new single‑family house has:

12 small plumbing penetrations through the exterior wall,
6 electrical conduit entries,
4 ventilation/exhaust terminations, and
10 window and door perimeter gaps found at rough‑in.

Action required under § 110.7:

Identify all 32 potential leakage points (12 + 6 + 4 + 10 = 32 openings). § 110.7 requires each be sealed with an appropriate method (caulk, gasket, weatherstrip, or other).
For each plumbing/electrical penetration, apply a durable sealed penetration (e.g., fire‑rated foam or listed caulk and a gasketed escutcheon consistent with manufacturer and local code practice). Record the sealing on the inspection checklist.
For window/door perimeters, install continuous weather‑stripping or continuous caulk at gaps consistent with manufacturer installation and local practice.
During inspection, the building official or energy consultant will verify that the identified joints and penetrations were sealed (visual verification is the minimum implied requirement of § 110.7). If your work involves ducts or systems that require leakage testing, perform the tests and meet the numeric limits in the applicable sections (not § 110.7). See § 150.2, § 160.3, § 180.2 for test thresholds and procedures.

Notes: The numeric counts in this example are illustrative. § 110.7 does not specify inspection checklists or a quantitative pass/fail for envelope leakage — it mandates that all potential leak sources be sealed.

Related provisions

§ 110.6 — Mandatory requirements for fenestration products and exterior doors (closely related to sealing window/door perimeters).
§ 150.2 — Single‑family residential provisions that include altered and new duct, insulation and sealing requirements (see duct sealing limits and altered system rules).
§ 160.3 — Field verification and diagnostic testing requirements (includes duct sealing and testing procedures referenced elsewhere).
§ 180.2 — Multifamily duct sealing and leakage requirements (quantified leakage targets and exceptions for multifamily).
§ 110.8 — Insulation certification and installation rules (not envelope sealing itself, but often verified alongside sealing).

If you need the exact Code paragraph text or the referenced quantitative leakage provisions and test procedures, I can extract the specific subsections and the related Reference Residential Appendix procedures next. The single controlling mandatory sealing sentence is in § 110.7.

Code references

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

§ 0.53 High relevance — show source text
thermal break|Operable|Tinted|NA|0.53|NA| |Metal, thermal break|Fixed|Tinted|NA|0.57|NA| |Nonmetal|Operable|Clear|0.74|0.65|0.70| |Nonmetal|Fixed|Clear|0.76|0.67|0.67| |Nonmetal|Operable|Tinted|0.60|0.53|NA| |Nonmetal|Fixed|Tinted|0.63|0.55|NA| |1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|

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ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

SECTION 110.7—MANDATORY REQUIREMENTS TO LIMIT AIR LEAKAGE

All joints, penetrations and other openings in the building envelope that are potential sources of air leakage shall be caulked, gasketed, weather-stripped or otherwise sealed to limit infiltration and exfiltration.

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, 25402.8, and 25943, Public Resources Code.
§ 110.7 High relevance — show source text
Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|1. Translucent or transparent panels shall use glass block values when not rated by NFRC 200.
2. Visible Transmittance (VT) shall be calculated by using Reference Nonresidential Appendix NA6.
3. Windows with window film applied that is not rated by NFRC 200 shall use the default values from this table.|

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ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

SECTION 110.7—MANDATORY REQUIREMENTS TO LIMIT AIR LEAKAGE

All joints, penetrations and other openings in the building envelope that are potential sources of air leakage shall be caulked, gasketed, weather-stripped or otherwise sealed to limit infiltration and exfiltration.

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, 25402.8, and 25943, Public Resources Code.

SECTION 110.8—MANDATORY REQUIREMENTS FOR INSULATION, ROOFING PRODUCTS AND RADIANT BARRIERS

(a) Insulation certification by manufacturers. All insulation shall be certified by Department of Consumer Affairs, Bureau of Household Goods and Services that the insulation conductive thermal performance is approved pursuant to the California Code of Regulations, Title 24, Part 12, Chapters 12 – 13, Article 3, “Standards for Insulating Material.”

(b) Installation of urea formaldehyde foam insulation. Urea formaldehyde foam insulation may be applied or installed only if:
1. It is installed in exterior side walls; and
2. A 4-mil-thick plastic polyethylene vapor retarder or equivalent plastic sheathing vapor retarder is installed between the urea formaldehyde foam insulation and the interior space in all applications.
(c) Flamespread rating of insulation. All insulating material shall be installed in compliance with the flamespread rating and smoke density requirements of the CBC.

(d) Installation of insulation in existing buildings. Insulation installed in an existing attic, or on an existing duct or water heater, shall comply with the applicable requirements of Subsections 1, 2 and 3 below. If a contractor installs the insulation, the contractor shall certify to the customer, in writing, that the insulation meets the applicable requirements of Subsections 1, 2 and 3 below.
1. Attics. If insulation is installed in the existing attic of a low-rise residential building, the R -value of the total amount of insulation (after addition of insulation to the amount, if any, already in the attic) shall meet the requirements of Section 150.0(a) for single-family buildings and Section 180.2(a)1 for multifamily buildings three habitable stories or fewer.
§ 323-9843 High relevance — show source text
State Librarian [SL]

library.ca.gov csllaw@library.ca.gov (916) 323-9843 Public Library Construction & Renovation

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HOW TO DETERMINE WHERE CHANGES HAVE BEEN MADE

Symbols in the margins indicate where changes have been made or language has been deleted.

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CONTENTS

ADMINISTRATIVE REGULATIONS . . . . . . . . . . . . . . . . . . . . . . . . 1

CALIFORNIA CODE OF REGULATIONS TITLE 24, PART 6 . . . . . 1

SUBCHAPTER 1 ALL OCCUPANCIES—GENERAL PROVISIONS . . .1

100.0 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

100.1 Definitions and Rules of Construction . . . . . . . . . . . . . 4

100.2 Calculation of Energy Budgets. . . . . . . . . . . . . . . . . . . 36

SUBCHAPTER 2 ALL OCCUPANCIES—MANDATORY

REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND

BUILDING COMPONENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

110.0 Systems and Equipment—General . . . . . . . . . . . . . . . 39

110.1 Mandatory Requirements for Appliances . . . . . . . . . 39

110.2 Mandatory Requirements for Space-Conditioning Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

110.3 Mandatory Requirements for Service Water-Heating Systems and Equipment . . . . . . . . . . . . . . . . . . . . . . . 52

110.4 Mandatory Requirements for Pool and Spa Systems and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

110.5 Natural Gas Central Furnaces, Cooking Equipment, Pool and Spa Heaters, and Fireplaces: Pilot Lights Prohibited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

110.6 Mandatory Requirements for Fenestration Products and Exterior Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

110.7 Mandatory Requirements to Limit Air Leakage . . . . 57

110.8 Mandatory Requirements for Insulation, Roofing Products and Radiant Barriers. . . . . . . . . . . . . . . . . . 57

110.9 Mandatory Requirements for Lighting Controls. . . . 59
§ 110.0 High relevance — show source text
110.0 Systems and Equipment—General . . . . . . . . . . . . . . . 39

110.1 Mandatory Requirements for Appliances . . . . . . . . . 39

110.2 Mandatory Requirements for Space-Conditioning Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

110.3 Mandatory Requirements for Service Water-Heating Systems and Equipment . . . . . . . . . . . . . . . . . . . . . . . 52

110.4 Mandatory Requirements for Pool and Spa Systems and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

110.5 Natural Gas Central Furnaces, Cooking Equipment, Pool and Spa Heaters, and Fireplaces: Pilot Lights Prohibited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

110.6 Mandatory Requirements for Fenestration Products and Exterior Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

110.7 Mandatory Requirements to Limit Air Leakage . . . . 57

110.8 Mandatory Requirements for Insulation, Roofing Products and Radiant Barriers. . . . . . . . . . . . . . . . . . 57

110.9 Mandatory Requirements for Lighting Controls. . . . 59

110.10 Mandatory Requirements for Solar Readiness. . . . . 60

110.11 Mandatory Requirements for Electrical Power Distribution System . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

110.12 Mandatory Requirements for Demand Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

SUBCHAPTER 3 NONRESIDENTIAL, HOTEL/MOTEL OCCUPANCIES, AND COVERED PROCESSES—MANDATORY REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

120.0 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

120.1 Requirements for Ventilation and Indoor Air Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

120.2 Required Controls for Space-Conditioning Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

120.3 Requirements for Pipe Insulation . . . . . . . . . . . . . . . . 75

120.4 Requirements for Air Distribution System Ducts and Plenums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
§ 160.3 High relevance — show source text
ii. For duct wrap, installed thickness shall be assumed to be 75 percent (25 percent compression) of nominal thickness.

iii. For factory-made flexible air ducts, the installed thickness shall be determined by dividing the difference between the actual outside diameter and nominal inside diameter by two. F. Duct labeling. Insulated flexible duct products installed to meet this requirement shall include labels, in maximum intervals of 3 feet, showing the thermal performance R- value for the duct insulation itself (excluding air films, vapor retarder or other duct components), based on the tests in Section 160.3(b)5D and the installed thickness determined by Section 160.3(b)5Eiii. G. Backdraft dampers. All fan systems, regardless of volumetric capacity, that exchange air between the building conditioned space and the outside of the building shall be provided with backdraft or automatic dampers to prevent unintended air leakage through the fan system when the fan system is not operating. H. Gravity ventilation dampers. All gravity ventilating systems that serve conditioned space shall be provided with either automatic or readily accessible, manually operated dampers in all openings to the outside except combustion inlet and outlet air openings and elevator shaft vents. I. Protection of insulation. Insulation shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind but not limited to the following: Insulation exposed to weather shall be suitable for outdoor service (e.g., protected by aluminum, sheet metal, painted canvas or plastic cover). Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation that can cause degradation of the material. J. Porous inner core flex duct. Flexible ducts having porous inner cores shall have a nonporous layer or air barrier between the inner core and the outer vapor barrier. K. Duct system sealing and leakage testing. When space-conditioning systems utilize forced air duct systems to supply conditioned air to an individual dwelling unit, the ducts shall be sealed, as confirmed through field verification and diagnostic testing, in accordance with all applicable procedures specified in Reference Residential Appendix RA3.1. Air handler airflow for calculation of duct leakage rate compliance targets shall be determined according to methods specified in Reference Residential Appendix RA3.1.4.2. For multifamily dwellings with the air-handling unit installed and the ducts connected directly to the air handler, regardless of duct system location: i. The total leakage of the duct system shall not exceed 12 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or ii. The duct system leakage to outside shall not exceed 6 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4.
- Exception 1 to Section 160.3(b)5K: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four
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MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. Exception 2 to Section 160.3(b)5K: Multifamily dwelling units in buildings four habitable stories and greater in Climate Zones 1, 3, 5 and 7. L.
§ 180.2 High relevance — show source text
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MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

C. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2AiicI or II then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5.

Exception to Section 180.2(b)2AiiaII: duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos. Exception 1 to 180.2(b)2Aii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iii. Altered space-conditioning system—duct sealing. In all climate zones, when a space-conditioning system serving a multifamily dwelling is altered by the installation or replacement of space-conditioning system equipment, including replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil, the duct system that is connected to the altered space-conditioning system equipment shall be sealed, as confirmed through field verification and diagnostic testing in accordance with the applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix RA3.1 and the leakage compliance criteria specified in Subsection a, b or c below. a. The measured duct leakage shall be equal to or less than 15 percent of air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or b. The measured duct leakage to outside shall be equal to or less than 10 percent of air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or c. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2Aiiia or b, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. Exception 1 to Section 180.2(b)2Aiii : duct sealing. Duct systems that are documented to have been previously sealed as confirmed through field verification and diagnostic testing in accordance with procedures in Reference Residential Appendix RA3.1. Exception 2 to Section 180.2(b)2Aiii: duct sealing. Duct systems with less than 40 linear feet as determined by visual inspection. Exception 3 to Section 180.2(b)2Aiii: duct sealing. Existing duct systems constructed, insulated or sealed with asbestos.

Exception 4 to Section 180.2(b)2Aiii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iv. **Altered space-conditioning system mechanical cooling.
§ 150.0 Medium relevance — show source text
Entirely new or complete replacement duct systems installed as part of an alteration is constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit’s existing duct system, including but not limited to registers, grilles, boots, air handler, coil, plenums, duct material; if the reused parts are accessible and can be sealed to prevent leakage. Entirely new or complete replacement duct systems shall also conform to the requirements of Sections 150.0(m)12 and 150.0(m)13. If the air handler and ducts are located within a vented attic, the requirements of Section 150.2(b)1J shall also be met.

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SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

b. Extension of an existing duct system. If the new ducts are an extension of an existing duct system serving single-family dwellings, the combined new and existing duct system shall meet one of the following requirements: I. The measured duct leakage shall be equal to or less than 10 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. The measured duct leakage to outside shall be equal to or less than 7 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or III. If it is not possible to meet the duct sealing requirements of either Section 150.2(b)1DiibI or 150.2(b)1DiibII, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. Exception to Section 150.2(b)1Diib: Duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos.

c. Altered ducts and duct system components in garage spaces. When new or replacement space-conditioning ducts, air-handling units, cooling or heating coils, or plenums are located in a garage space, compliance with either I or II below is required. I. The measured system duct leakage shall be less than or equal to 6 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. All accessible leaks located in the garage space shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. E. Altered space-conditioning system—duct sealing. In all climate zones, when a space-conditioning system serving a single-family dwelling is altered by the installation or replacement of space-conditioning system equipment, including replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil, the duct system that is connected to the altered space-conditioning system equipment shall be sealed, as confirmed through field verification and diagnostic testing in accordance with the applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix RA3.1, and the leakage compliance criteria specified in Subsection i, ii, or iii below.
§ 180.2 Medium relevance — show source text

TABLE 180.2-C—DUCT INSULATION R-VALUE Col2 Col3

Climate Zone 3, 5 through 7 1, 2, 4, 8 through 16

Duct_R-_Value R-6 R-8

I. Entirely new or complete replacement duct system. If the new ducts form an entirely new or complete replacement duct system directly connected to the air handler, the duct system shall meet one of the following requirements: A. The total leakage of the duct system shall not exceed 12 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1,

or

B. The duct system leakage to outside shall not exceed 6 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4. Entirely new or complete replacement duct systems installed as part of an alteration are constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit's existing duct system, including but not limited to registers, grilles, boots, air handler, coil, plenums and duct material, if the reused parts are accessible and can be sealed to prevent leakage. Entirely new or complete replacement duct systems shall also conform to the requirements of Sections 160.2(a)1 and 160.3(b)5L. If the air handler and ducts are located within a vented attic, the requirements of Section 180.2(b)1Bi shall also be met. II. Extension of an existing duct system. If the new ducts are an extension of an existing duct system serving multifamily dwellings, the combined new and existing duct system shall meet one of the following requirements: A. The measured duct leakage shall be equal to or less than 15 percent of air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or B. The measured duct leakage to outside shall be equal to or less than 10 percent of air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or

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MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

C. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2AiicI or II then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5.

Exception to Section 180.2(b)2AiiaII: duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos. Exception 1 to 180.2(b)2Aii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iii. **Altered space-conditioning system—duct sealing.
§ 150.2 Medium relevance — show source text
D. Altered duct systems—duct sealing. In all climate zones, when more than 25 feet of new or replacement spaceconditioning system ducts are installed, the ducts shall comply with the applicable requirements of Subsections i and ii below. Additionally, when altered ducts, air-handling units, cooling or heating coils, or plenums are located in garage spaces, the system shall comply with Subsection 150.2(b)1Diic regardless of the length of any new or replacement space-conditioning ducts installed in the garage space. i. New ducts located in unconditioned space shall meet the applicable requirements of Sections 150.0(m)1 through 150.0(m)10, and the duct insulation requirements of Table 150.2-D; and

TABLE 150.2-D—DUCT INSULATION R-VALUE Col2 Col3

Climate Zone 3, 5 through 7 1, 2, 4, 8 through 16

DuctR-Value R-6 R-8

ii. The altered duct system, regardless of location, shall be sealed as confirmed through field verification and diagnostic testing in accordance with all applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix Section RA3.1, utilizing the leakage compliance criteria specified in Subsection a or b below.

a. Entirely new or complete replacement duct system. If the new ducts form an entirely new or complete replacement duct system directly connected to the air handler, the duct system measured leakage shall be equal to or less than 5 percent of the system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1. Entirely new or complete replacement duct systems installed as part of an alteration is constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit’s existing duct system, including but not limited to registers, grilles, boots, air handler, coil, plenums, duct material; if the reused parts are accessible and can be sealed to prevent leakage. Entirely new or complete replacement duct systems shall also conform to the requirements of Sections 150.0(m)12 and 150.0(m)13. If the air handler and ducts are located within a vented attic, the requirements of Section 150.2(b)1J shall also be met.

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SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

b. Extension of an existing duct system. If the new ducts are an extension of an existing duct system serving single-family dwellings, the combined new and existing duct system shall meet one of the following requirements: I. The measured duct leakage shall be equal to or less than 10 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. The measured duct leakage to outside shall be equal to or less than 7 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or III.
§ 140.4 Medium relevance — show source text
Only the high limit control devices listed are allowed to be used and at the setpoints listed. Others such as Dew Point, Fixed Enthalpy, Electronic Enthalpy, and Differential Enthalpy
Controls may not be used in any climate zone for compliance with Section 140.4(e)1 unless approval for use is provided by the Energy Commission Executive Director.
b. Devices with selectable (rather than adjustable) setpoints shall be capable of being set to within 2°F and 2 Btu/lb of the setpoint listed.
c. At altitudes substantially different than sea level, the Fixed Enthalpy limit value shall be set to the enthalpy value at 75°F and 50% relative humidity. As an example, at approx-
imately 6,000 foot elevation, the fixed enthalpy limit is approximately 30.7 Btu/lb.|a. Only the high limit control devices listed are allowed to be used and at the setpoints listed. Others such as Dew Point, Fixed Enthalpy, Electronic Enthalpy, and Differential Enthalpy
Controls may not be used in any climate zone for compliance with Section 140.4(e)1 unless approval for use is provided by the Energy Commission Executive Director.
b. Devices with selectable (rather than adjustable) setpoints shall be capable of being set to within 2°F and 2 Btu/lb of the setpoint listed.
c. At altitudes substantially different than sea level, the Fixed Enthalpy limit value shall be set to the enthalpy value at 75°F and 50% relative humidity. As an example, at approx-
imately 6,000 foot elevation, the fixed enthalpy limit is approximately 30.7 Btu/lb.|

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NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—PERFORMANCE AND PRESCRIPTIVE

COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY

D. If controlled by a DDC system, configured with control sequences of operation in accordance with ASHRAE Guideline 36.

E. The air economizer and all air dampers shall have the following features: i. Warranty. 5-year manufacturer warranty of economizer assembly. ii. Damper reliability testing. Suppliers of economizers shall certify that the economizer assembly, including but not limited to outdoor air damper, return air damper, drive linkage and actuator, have been tested and are able to open and close against the rated airflow and pressure of the system for 60,000 damper opening and closing cycles. iii. Damper leakage. Economizer outdoor air and return air dampers shall have a maximum leakage rate of 10 cfm/sf at 250 Pascals (1.0 in. of water) when tested in accordance with AMCA Standard 500-D. The economizer outside air and return air damper leakage rates shall be certified to the Energy Commission in accordance with Section 110.0.
§ 160.3 Medium relevance — show source text
3(a)2H, 160.3(b)5A,160.3(b)5K-L, 160.3(c)2, 170.1(d)2, 170.2(c)3B, 4C, Table 170.2-K, 180.2(b)2 Infiltration 110.6(a)1, 150.0(m)1B, 160.3(b)5A Leakage 10-111(a), 110.6(a)1, 110.7, 140.3(a)9, 140.4(b)5, 141.0(b)2Q, 150.0(a)3, 150.0(k)1C, 150.0(m)7, 150.1(b)3B, 160.1(a)1, 160.3(b)G, 160.5(a)1C, 170.1(d)2H, 170.2(c)2E

Permeance 140.3(a)9 Quality classification 120.1(g)7, 160.2(c)8G Release valve 110.3(c)4A Sealing 150.2(a)1A, 180.1(a)1A Supply 120.2(f), 120.6(e)4, 140.4(d)2, 160.3(a)2E, 170.2(c)4B Ventilation 10-103.2(b)1B, 10-103.2(c)3B, 120.1(a)2, 120.1(d)4, 120.1(f)2, 120.5(a)1, 140.4(b)4, 150.0(o)1B, 160.2(a)2, 160.2(b)2A, 160.2(c)5D, 160.2(c)7B, 160.3(d)1A, 170.2(c)2D Air Conditioners and Condensing Units – Minimum Efficiency Requirements Table 110.2-A Air Conditioning Contractors of America (ACCA) ACCA Manual J 150.0(h), 160.3(b)1 Air Economizer High Limit Shut Off Control Requirements Table 140.4-G, Table 170.2-G Air Movement and Control Association (AMCA) Standard 500-D 140.4(e)2D, 170.2(c)4C Air-conditioning, Heating, and Refrigeration Institute (AHRI) AHRI Standard 680 120.1(c)1, 150.0(m)12, Table 150.0-B, Table 150.0-C, 160.2(b)1, Table 160.3-A, Table 160.3-B Air-Cooled Gas-engine Heat Pumps Table 110.2-C

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INDEX
§ 1.8.3.2.3 Medium relevance — show source text
(3) For applications subject to the Special Occupancy Parks Act as referenced in Section 1.8.3.2.3 of this code, refer to Health and Safety Code, Division 13, Part 2.3, commencing with Section 18860, and Cali- fornia Code of Regulations, Title 25, Division 1, Chapter 2.2, commencing with Section 2000.

(4) For applications subject to the Employee Housing Act as referenced in Section 1.8.3.2.4 of this code, refer to Health and Safety Code, Division 13, Part 1, commencing with Section 17000 and California Code of Regulations, Title 25, Division 1, Chapter 1, Subchapter 3, commencing with Section 600.

(5) For applications subject to the Factory-Built Housing Law as referenced in Section 1.8.3.2.5 of this code, refer to Health and Safety Code, Division 13, Part 6, commencing with Section 19960 and California Code of Regulations, Title 25, Division 1, Chapter 3, Subchapter 1, commencing with Section 3000.

1.8.6 Local Modification by Ordinance or Regulation.

1.8.6.1 General. Subject to other provisions of law, a city, county, or city and county may make changes to the provi- sions adopted by the Department of Housing and Community Development. If any city, county, or city and county does not amend, add, or repeal by local ordi- nances or regulations the provisions published in this code or other regulations promulgated by the Department of Housing and Community Development, those provi- sions shall be applicable and shall become effective 180 days after publication by the California Building Stan- dards Commission. Amendments, additions, and deletions to this code adopted by a city, county, or city and county pursuant to California Health and Safety Code Sections 17958.5, 17958.7 and 18941.5, together with all appli- cable portions of this code, shall also become effective 180 days after publication of the California Building Standards Code by the California Building Standards Commission.

1.8.6.2 Findings, Filings, and Rejections of Local Modifications. Prior to making any modifications or establishing more restrictive building standards, the governing body shall make express findings and filings,

as required by California Health and Safety Code Section 17958.7, showing that such modifications are reasonably necessary due to local climatic, geological, or topo- graphical conditions. No modification shall become effective or operative unless the following requirements

are met:

(1) The express findings shall be made available as a public record.

(2) A copy of the modification and express finding, each document marked to cross-reference the other, shall be filed with the California Building Standards Commission for a city, county, or city and county, and with the Department of Housing and Commu- nity Development for fire protection districts.

(3) The California Building Standards Commission has not rejected the modification or change.

Nothing in this section shall limit the authority of fire protection districts pursuant to California Health and Safety Code Section 13869.7(a).

TABLE 180.2-C—DUCT INSULATION R-VALUE	Col2	Col3
Climate Zone	3, 5 through 7	1, 2, 4, 8 through 16
Duct_R-_Value	R-6	R-8

TABLE 150.2-D—DUCT INSULATION R-VALUE	Col2	Col3
Climate Zone	3, 5 through 7	1, 2, 4, 8 through 16
DuctR-Value	R-6	R-8

Frequently asked questions

Do I need to perform an airtightness test (blower door) because of § 110.7?

No — § 110.7 itself mandates that openings be sealed but does not require a whole‑building airtightness (blower door) test. Quantitative testing requirements (and where they apply) are specified in other Code sections and reference appendices. See § 160.3, § 150.2, § 180.2 for testing and duct leakage rules.

Does § 110.7 tell me which sealant product to use?

No — § 110.7 prescribes the methods (caulk, gasket, weather‑strip, or otherwise sealed) but does not specify brands or product test standards; follow manufacturer instructions and any applicable material/assembly standards referenced elsewhere in the Code.

Are ducts covered by § 110.7?

Ducts are related but treated separately. § 110.7 addresses envelope openings; duct sealing, leakage limits, and test procedures are in sections like § 160.3, § 150.2, and § 180.2. Meet both the envelope sealing requirement and the specific duct sealing/testing requirements where applicable.

If I seal accessible leaks but not concealed ones, am I compliant?

§ 110.7 requires sealing of all potential leak sources. Concealed leaks that remain unsealed but were accessible during construction could be cited by the enforcing authority; document attempts to seal and explain inaccessible conditions to the inspector. The Code text is general — enforcement interprets whether a particular leak was reasonably sealable.

Where do I find the detailed procedures for verifying duct sealing?

Detailed field verification and diagnostic testing procedures are in the Reference Residential Appendices and sections such as § 160.3, and the leakage criteria are in § 150.2 and § 180.2 depending on occupancy type.

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