Title 19 — MARIN COUNTY BUILDING CODE[1]
Marin County Building Code · 2026-07 edition · ingested 2026-07-08 · Marin County
Source: library.municode.com (print export)
Title 19 - MARIN COUNTY BUILDING CODE[[1]]
Footnotes:
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Note— Ord. No. 3549, § II(exh. A), 2010 renamed Title 19 as set out herein, formerly titled "Buildings." Ord. No. 3658, § II(exh. A), adopted Nov. 15, 2016, amended Title 19 in its entirety to read as herein set out. See editor's notes to each chapter.
Chapter 19.04 - BUILDING REGULATIONS[[2]]
Footnotes:
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Editor's note— Ord. No. 3658, § II(exh. A), adopted Nov. 15, 2016, amended Ch. 19.04 in its entirety to read as herein set out. Former Ch. 19.04, §§ 19.04.010—19.04.170, pertained to similar subject matter, and derived from Ord. No. 3607, § II(exh. A), adopted Nov. 12, 2013; Ord. No. 3619, § II(exh. A, §§ I, VI), 2014; and, previously, Ord. No. 3549, § II(exh. A), adopted Nov. 30, 2010.
Subchapter 1 - General Provisions
19.04.140 - Standards for compliance. ¶
The Marin County Green Building Requirements define compliance thresholds for different projects that are covered by this chapter. These standards are summarized below in Table 1. The energy efficiency and electrification measures menu and specifications are detailed in Tables 2 and 3. Table 1: Requirements by Project Type and Size
| Project Type and Size | Green Building Requirements | Energy Efciency Requirements | Electric Vehicle Requirements |
|---|---|---|---|
| Single and Two-Family Newly Constructed or New Construction |
CALGreen Tier 1, except energy efciency measures |
Comply with 2025 California Energy Code |
CALGreen Tier 1 |
| Multifamily Residential Newly Constructed or New Construction |
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| Hotels and Motels Newly Constructed or New Construction |
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| Nonresidential Newly Constructed or New Construction |
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| Single and Two-Family Additions and Alterations less than 500 square feet |
CALGreen Mandatory | Comply with 2025 California Energy Code |
CAL Green Mandatory AND If upgrading the main electrical service panel, comply with CALGreen Measure A4.106.8.1 |
| Single and Two-Family Additions and Alterations 500 square feet or greater |
CALGreen Tier 1, except energy efciency measures |
Comply with 2025 California Energy Code AND |
CALGreen Tier 1 AND |
| Using the Measure Menu in Table 2, achieve a total score that is equal to or greater than the Target Score for the applicable climate zone. If applicable to your project, complete Electric Readiness measures in Section 150.0 (x) |
If the project is upgrading the main electrical service panel, comply with CALGreen Measure A4.106.8.1 |
||
| --- | --- | --- | --- |
| Multi-family Residential Additions and Alterations less than 500 square feet |
CALGreen Mandatory | Comply with 2025 California Energy Code |
CALGreen Mandatory AND If the main electrical service panel is modifed, add designated electrical capacity for 20% of onsite parking spaces to be Level 2 EV Ready. |
| Multifamily Residential Additions and Alterations 500 square feet or greater |
CALGreen Tier 1, except energy efciency measures |
CALGreen Tier 1 AND If the service panel is modifed, add designated electrical capacity for 20% of onsite parking spaces to be Level 2 EV Ready. |
|
| Hotels and Motels Additions and Alterations |
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| Nonresidential Additions and Alterations |
The following conditions also apply to Table 1:
(a)
Cumulative new construction or remodels during the preceding 36-month period from the acceptance of this application shall be considered as a single covered project, and subject to the highest compliance threshold based on the cumulative project size or valuation.
(b)
Mixed use (residential and commercial) projects must comply either with the applicable covered project requirements for the respective residential and commercial portions of the project or may propose to utilize a mixed-use rating system, subject to approval by the chief building official.
Table 2: Energy and Electrification Menu of Measures by Climate Zone
| Measure | Climate Zone | Steps | ||
|---|---|---|---|---|
| 2 | 3 | 1) Choose your Climate Zone using CEC toolfnder1 |
||
| Specifcation | Spec. ID (Refer to Table 3) |
Target Score | 2) Minimum Target Score needed to coml |
|
| 9 | 7 | py (1 point = 1MMBTU savings per yr.) |
||
| Lighting | E1 | Mandatory | 3) Choose a measure or a | |
| --- | --- | --- | --- | --- |
| Water Heating Package | E2 | 1 | 1 | |
| Air Sealing | E3 | 1 | 1 | |
| R-38 Attic Insulation | E4.A | 2 | 1 | |
| R-49 Attic Insulation | E4.B | 2 | 2 | |
| Duct Sealing | E5 | 3 | 2 | |
| New Ducts, R-8 Insulation + Duct Sealing |
E6.A | 6 | 4 | |
| New Ducts, R-6 Insulation + Duct Sealing |
E6.B | 6 | 4 | combination of measures that adds up to the minimum target score above |
| Windows | E7 | 3 | 3 | based on CZ. Measures listed as "Mandatory" MUST be installed. |
| R-19 Raised Floor Insulation | E10.A | 8 | 9 | 4) Use the Secifcation Number |
| R-30 Raised Floor Insulation | E.10B | 9 | 10 | p (Spec. ID) column as a key and |
| Radiant Barrier Under Roof (when re- roofng) |
E12 | 1 | 1 | conform to the specifcations in Table 3 below. Table 3 describes, specifes, and details compliance with each |
| HPWH (repl gas) | FS1 | 12 | 12 | corresponding measure. |
| High Ef HPWH (repl gas) | FS2 | 13 | 13 | |
| HPWH (repl electric) | FS3 | 4 | 5 | |
| High Ef HPWH (repl electric) | FS4 | 5 | 6 | |
| HVAC Heat Pump | FS5 | 15 | 12 | |
| High Ef HVAC Heat Pump | FS6 | 16 | 12 | |
| Heat Pump Clothes Dryer | FS8 | 1 | 1 | |
| Induction Cooktop | FS9 | 1 | 1 | |
| Solar PV + Electric Ready Pre-Wire | PV | 13 | 12 | |
| 1California Energy Commission climate zone tool fnder at https://www.energy.ca.gov/programs-and-topics/programs/building-energy- efciency-standards/climate-zone-tool-maps-and. |
The following conditions also apply to Table 2:
Unless otherwise specified, the requirements shall apply to the entire dwelling unit, not just the additional or altered portion.
(b) ;hg;Measures from the Measure Menu in Table 2 and specified in Table 3, that already exist in the home, may be counted towards compliance with these requirements, unless otherwise specified in Table 3.
(c) ;hg;Measures from the Measure Menu in Table 2 that are to be installed to satisfy requirements under the State Energy Code, Title 24, Part 6, may also be counted towards compliance with these requirements. Where these requirements conflict with other Energy Code requirements, the stricter requirements shall prevail.
Table 3. List of Measure Specifications
| ID | Measure Specifcation |
|---|---|
| Energy Measures | |
| E1 | Lighting Measures ? Install lighting with an efciency of 45 lumens per watt or greater in all interior and exterior screw-in fxtures. Install photocell, occupancy sensor or energy management system controls that meet the requirements of 150.0(k)3 in all outdoor lighting permanently mounted to a residential building or to other buildings on the same lot. |
| E2 | Water Heating Package: Insulate all accessible hot water pipes with pipe insulation a minimum of ¾ inch thick. This includes insulating the supply pipe leaving the water heater, piping to faucets underneath sinks, and accessible pipes in attic spaces or crawlspaces. Upgrade fttings in sinks and showers to meet current California Green Building Standards Code (Title 24, Part 11) Section 4.303 water efciency requirements. Exception: Upgraded fxtures are not required if existing fxtures have rated or measured fow rates of no more than ten percent greater than 2025 California Green Building Standards Code (Title 24, Part 11) Section 4.303 water efciency requirements. |
| --- | --- |
| E3 | Air Sealing: Seal all accessible cracks, holes, and gaps in the building envelope at walls, foors, and ceilings. Pay special attention to penetrations including plumbing, electrical, and mechanical vents, recessed can light luminaires, and windows. Weather-strip doors if not already present. Verifcation shall be conducted following a prescriptive checklist that outlines which building aspects need to be addressed by the permit applicant and verifed by an inspector. Compliance can also be demonstrated with blower door testing conducted by a certifed ECC Rater no more than three years prior to the permit application date that either: a) shows at least a 30 percent reduction from pre-retroft conditions; or b) shows that the number of air changes per hour at 50 Pascals pressure diference (ACH50) does not exceed ten for Pre-1978 vintage buildings, seven for 1978 to 1991 vintage buildings and fve for 1992-2010 vintage buildings. If combustion appliances are located within the pressure boundary of the building, conduct a combustion safety test by a certifed ECC Rater or a professional certifed by the Building Performance Institute, in accordance with the BPI Technical Standards for the Building Analyst Professional. |
| E4.A | R-38 Attic Insulation: Attic insulation shall be installed to achieve a weighted assembly U-factor of 0.025 or insulation installed at the ceiling level shall have a thermal resistance of R-38 or greater for the insulation alone. Recessed downlight luminaires in the ceiling shall be covered with insulation to the same depth as the rest of the ceiling. Luminaires not rated for insulation contact must be replaced or ftted with a fre-proof cover that allows for insulation to be installed directly over the cover. Exception: In buildings where existing R-30 is present and existing recessed downlight luminaires are not rated for insulation contact, insulation is not required to be installed over the luminaires. |
| E4.B | R-49 Attic Insulation: Attic insulation shall be installed to achieve a weighted assembly U-factor of 0.020 or insulation installed at the ceiling level shall have a thermal resistance of R-49 or greater for the insulation alone. Recessed downlight luminaires in the ceiling shall be covered with insulation to the same depth as the rest of the ceiling. Luminaires not rated for insulation contact must be replaced or ftted with a fre-proof cover that allows for insulation to be installed directly over the cover. Exception: In buildings where existing R-30 is present and existing recessed downlight luminaires are not rated for insulation contact, insulation is not required to be installed over the luminaires. |
| E5 | Duct Sealing: Air seal all space conditioning ductwork to meet the requirements of the 2025 Title 24,Part 6, Section 150.2(b)1E. The duct system must be tested by a ECC Rater no more than three years prior to the Covered Single Family Project permit application date to verify the duct sealing and confrm that the requirements have been met. This measure may not be combined with the New Ducts and Duct Sealing measure in this Table. Exception: Buildings without ductwork or where the ducts are in conditioned space. |
| E6.A | New Ducts, R-6 insulation + Duct Sealing: Replace existing space conditioning ductwork with new R-6 ducts that meet the requirements of 2025 Title 24 Section 150.0(m)11. This measure may not be combined with the Duct Sealing measure in this Table. To qualify, a preexisting measure must have been installed no more than three years before the Covered Single Family Project permit application date. |
| E6.B | New Ducts, R-8 insulation + Duct Sealing: Replace existing space conditioning ductwork with new R-8 ducts that meet the requirements of 2025 Title 24 Section 150.0(m)11. This measure may not be combined with the Duct Sealing measure in this Table. To qualify, a preexisting measure must have been installed no more than three years before the Covered Single Family Project permit application date. |
| E7 | Windows: Replace at least 50% of existing windows with high performance windows with an area-weighted average U-factor no greater than 0.27. |
| E10.A | R-19 Floor Insulation: Raised-foors shall be insulated such that the foor assembly has an assembly U-factor equal to or less than U-0.037 or shall be insulated between wood framing with insulation having an R-value equal to or greater than R-19. |
| E10.B | (alternate) R-30 Floor Insulation: Raised-foors shall be insulated such that the foor assembly has an assembly U-factor equal to or less than U-0.028 or shall be insulated between wood framing with insulation having an R-value equal to or greater than R-30. |
| ID | Measure Specifcation |
|---|---|
| E12 | Radiant Barrier: A radiant barrier that meets the requirements of Section 150.1(c)2 shall be installed under at least 50% of the roof surface. |
| Fuel Substitution and Solar PV Measures | |
| FS1 | Heat Pump Water Heater (HPWH) Replacing Gas: Replace existing natural gas water heater with a heat pump water heater that meets the requirements of Sections 110.3 and 150.2(b)1.H.iii.b. |
| --- | --- |
| FS2 | High Efciency Heat Pump Water Heater (HPWH) Replacing Gas: Replace existing natural gas water heater with heat pump water heater with a Northwest Energy Efciency Alliance (NEEA) Tier 3 or higher rating that also meets the requirements of Sections 110.3 and 150.2(b)1.H.iii.c. |
| FS3 | Heat Pump Water Heater (HPWH) Replacing Electric: Replace existing electric resistance water heater with a heat pump water heater that meets the requirements of Sections 110.3 and 150.2(b)1.H.iii.b. |
| FS4 | High Efciency Heat Pump Water Heater (HPWH) Replacing Electric: Replace existing electric resistance water heater with heat pump water heater with a Northwest Energy Efciency Alliance (NEEA) Tier 3 or higher rating that also meets the requirements of Sections 110.3, and 150.2(b)1.H.iii.c. |
| FS5 | Heat Pump Space Conditioning System: Replace all existing gas and electric resistance primary space heating systems with an electric-only heat pump system that meets the requirements of Sections 110.3, 150.2(b)1.C, 150.2(b)1.E, 150.2(b)1.F, and 150.2(b)1.G. |
| FS6 | High Efciency Heat Pump Space Conditioning System: Replace all existing gas and electric resistance primary space heating systems with a system that meets the requirements of Sections 110.3 and 150.2(b)1.C, 150.2(b)1.E, 150.2(b)1.F, and 150.2(b)1.G and one of the following: A. A ducted electric-only heat pump system with a SEER2 rating of 16.5 or greater, an EER2 rating of 12.48 or greater and an HSPF2 rating of 9.5 or greater; or B. A ductless mini-split heat pump system with a SEER2 rating of 14.3 or greater, an EER2 rating of 11.7 or greater and an HSPF2 rating of 7.5 or greater |
| FS8 | Heat Pump Clothes Dryer: Replace existing electric resistance clothes dryer with heat pump dryer with no resistance element and cap gas line. |
| FS9 | Induction Cooktop: Replace all existing gas and electric resistance stove tops with inductive stove top and cap the gas line. |
| PV.A | Solar PV: Install a solar PV system that meets the requirements of Section 150.1(c)14. |
(Ord. No. 3836, § II, 11-18-2025)
19.04.150 - Incentives for compliance. ¶
In addition to the required standards for compliance, the Board of Supervisors may establish by resolution, financial or application processing incentives and/or award or recognition programs to encourage higher levels of green building compliance for a project.
(Ord. No. 3836, § II, 11-18-2025)
19.04.160 - Administrative procedures. ¶
The procedures for compliance with the provisions of this chapter shall include, but not be limited to the following:
(a)
Project design. Applicants for a covered project are strongly encouraged to involve a qualified green building rater in the initial design phases of the project in advance of submittal of an application to determine applicable green building compliance thresholds and the most cost effective and appropriate means of achieving compliance.
(b)
Planning applications. If a discretionary planning application is required for a covered project, applicants should be prepared to identify expected green building measures to be included in the project to achieve the compliance thresholds. Applicants should identify any anticipated difficulties in achieving compliance and any exemptions from the requirements of this chapter that may be requested.
(c)
Building plan check review. Upon submittal of an application for a building permit, building plans for any covered project shall include a green building program description and completed checklist. The checklist shall be incorporated onto a separate full-sized plan sheet included with the building plans. Evidence that the project, as indicated by the project plans and green building program description, will achieve the standards for compliance outlined in Section 19.04.140, shall be provided prior to issuance of a building permit.
(d)
Changes during construction. During the construction process, alternate green building measures may be substituted, provided that documentation of the proposed change and the project's continued ability to achieve the standards for compliance to the chief building official shall be provided.
(e)
Final building inspection. Prior to final building inspection and occupancy for any covered project, evidence that project construction has achieved the required compliance set forth in the standards for compliance outlined in Section 19.04.140 shall be provided. The chief building official shall review the documentation submitted by the applicant and determine whether the project has achieved the compliance threshold as set forth in the standards for compliance outlined in Section 19.04.140. If the chief building official determines that the applicant has met these requirements, the final building inspection may proceed.
(f)
Conflict with other laws. The provisions of this chapter are intended to be in addition to and not in conflict with other laws, regulations and ordinances relating to building construction and site development. If any provision of this chapter conflicts with any duly adopted and valid statutes or regulations of the federal government or the state of California, the federal or state statutes or regulations shall take precedence.
(Ord. No. 3836, § II, 11-18-2025)
19.04.170 - Exemptions.
(a)
The provisions of this chapter shall not apply to:
(1)
Buildings which are temporary (such as construction trailers).
(2)
Building area which is not or is not intended to be conditioned space.
(3)
Any requirements of this chapter which would impair the historic integrity of any building listed on a local, state, or federal register of historic structures, as determined by the chief building official and as regulated by the California Historic Building Code (Title 24, Part 8). In making such a determination, the chief building official may require the submittal of an evaluation by an architectural historian or similar expert.
(b)
As outlined in the 2025 CALGreen code, Section 4.106.4 and 5.106.5, applicants may be exempted from the electric vehicle changing requirements on a case-by-case basis where the local enforcing agency has determined EV charging and infrastructure are not feasible based upon one or more of the following conditions:
(1)
Where there is no local utility power supply or the local utility is unable to supply adequate power.
(2)
Where there is evidence suitable to the local enforcing agency substantiating that additional local utility infrastructure design requirements, directly related to the implementation of Section 4.106.4 and 5.106.5 may adversely impact the construction cost of the project.
(3)
ADUs and JADUs without additional parking facilities.
(4)
Areas of parking facilities served by parking lifts, including but not limited to, automated mechanicalaccess open parking garages as defined in the California Building Code; or parking facilities otherwise of supporting electric vehicle charging.
(c)
Hardship or infeasibility exemption. If an applicant for a covered project believes that circumstances exist that make it a hardship or infeasible to meet the requirements of this chapter, the applicant may request an exemption as set forth below. In applying for an exemption, the burden is on the applicant to show hardship or infeasibility.
(1)
Application. Based on the following, the applicant shall identify in writing the specific requirements of the standards for compliance that the project is unable to achieve and the circumstances that make it a hardship or infeasible for the project to comply with this chapter. The applicant may not petition for relief from any requirement of the 2025 California Energy Code (Title 24, Part 6) and referenced standards, or the
2025 California Green Building Standards (Title 24, Part 11) of the California Building Standards Code. Circumstances that constitute hardship or infeasibility shall include one of the following:
a.
That the cost of achieving compliance is disproportionate to the overall cost of the project;
b.
That strict compliance with these standards would create or maintain a hazardous condition(s) and present a life safety risk to the occupants.
(2)
Granting of exemption. If the chief building official determines that it is a hardship or infeasible for the applicant to fully meet the requirements of this chapter and that granting the requested exemption will not cause the building to fail to comply with the 2025 California Energy Code (Title 24, Part 6) and referenced standards, or the 2025 California Green Building Standards (Title 24, Part 11) of the California Building Standards Code, the chief building official shall determine the maximum feasible threshold of compliance reasonably achievable for the project. In making this determination, the chief building official shall consider whether alternate, practical means of achieving the objectives of this chapter can be satisfied, such as reducing comparable energy use at an off-site location within the county. If an exemption is granted, the applicant shall be required to comply with this chapter in all other respects and shall be required to achieve the threshold of compliance determined to be achievable by the chief building official.
(3)
Denial of exception. If the chief building official determines that it is reasonably possible for the applicant to fully meet the requirements of this chapter, the request shall be denied, and the applicant shall be notified of the decision in writing. The project and compliance documentation shall be modified to comply with the standards for compliance.
(4)
Appeal. Any aggrieved applicant or person may appeal the determination of the chief building official regarding the granting or denial of an exemption or compliance with any other provision of this chapter. An appeal of a determination of the chief building official shall be filed in writing and processed in accordance with the provisions of Section 19.04.028 of this code.
(Ord. No. 3836, § II, 11-18-2025)
Chapter 19.05 - STREET IMPROVEMENTS REQUIRED ABUTTING BUILDING SITES[[4]]
Footnotes:
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Editor's note— Ord. No. 3658, § II(exh. A), adopted Nov. 15, 2016, amended Ch. 19.05 in its entirety to read as herein set out. Former Ch. 19.05, §§ 19.05.010—19.05.128, pertained to similar subject matter, and
derived from Ord. No. 3607, § II(exh. A), adopted Nov. 12, 2013; and, previously, Ord. No. 3549, § II(exh. A), adopted Nov. 30, 2010. For full derivative history see disposition tables.