Sonoma County enforces 2025 CBC, T24 Pt 2 based on 2024 IBC with 2 local amendments on top. The amendments are the part that gets sets corrected. The state edition is only the floor.
Current edition
2025 Title 24
Prior edition
2022 Title 24
Code authority
Permit Sonoma (County of Sonoma Permit and Resource Management)
Edition changeover: Projects with a complete application on or before 2025-12-31 may still be reviewed under the 2022 Title 24.
Adopted code and local amendments by discipline
Adopted code editions and local amendments by discipline
Discipline
Adopted code
Local amendment
Building
2025 CBC, T24 Pt 2 based on 2024 IBC
Sonoma County Ord. Nos. 6539 + 6541 (adopted ~2025-12-09 [verify], per CBSC filings; municode Ch. 7 not yet recodified): Chapter 7 Building Regulations
Residential
2025 CRC, T24 Pt 2.5 based on 2024 IRC
n/a
Existing buildings
2025 CEBC, T24 Pt 10 based on 2024 IEBC
n/a
Fire
2025 CFC, T24 Pt 9 based on 2024 IFC
n/a
Electrical
2025 CEC, T24 Pt 3 based on 2023 NEC
n/a
Mechanical
2025 CMC, T24 Pt 4 based on 2024 UMC
n/a
Plumbing
2025 CPC, T24 Pt 5 based on 2024 UPC
n/a
Energy
2025 Energy Code, T24 Pt 6
n/a
Green / sustainability
2025 CALGreen, T24 Pt 11
n/a
Accessibility
2025 CBC Ch 11A/11B, T24 Pt 2
n/a
Wildland-urban interface
2025 CA-WUIC, T24 Pt 7 based on 2024 IWUIC
n/a
Historical buildings
2025 CHBC, T24 Pt 8
n/a
Administrative
2025 CAC, T24 Pt 1
n/a
Zoning
No state-adopted code
Local zoning ordinance (city or county), subject to state preemptionLocal text supersedes the state code
Unincorporated communities Sonoma County reviews
These communities have no city building department of their own. The county is the authority having jurisdiction, so this page's code stack is the one that applies.
Guerneville · Monte Rio · Occidental · Forestville · Graton · Penngrove · Kenwood · Glen Ellen · El Verano · Boyes Hot Springs · Fetters Hot Springs-Agua Caliente · Bodega Bay · Jenner · Cazadero · The Sea Ranch · Larkfield-Wikiup
What Sonoma County actually amended
Quoted from the adopted ordinance. These are the provisions that differ from the state code, which is where most correction lists come from. Excerpts, not the whole ordinance. Follow the source link for the full text.
101.4.4 · Property maintenance. The provisions of CBC Sections 116 Unsafe
101.4.4. Property maintenance. The provisions of CBC Sections 116 Unsafe
Structures and Equipment of the CBC as amended by Sonoma County Code
by adding definitions for “unsafe or dangerous buildings” and “nuisance” to
Sonoma County Code section 7-19, shall apply to existing buildings and
premises.
by the chief building official or the use of which has been ordered to be
discontinued by the chief building official until the chief building official
authorizes the reconnection and use of such equipment. […]
105.2 · Work exempt from permit. Exemption from permit requirements of this
105.2 Work exempt from permit. Exemption from permit requirements of this
section shall not be deemed to grant authorization for any work to be done in
any manner in violation of the provisions of this code or any other laws or
ordinances of the jurisdiction. Such exempt structures must meet all other
applicable requirements of this jurisdiction, including required minimum
distances from property lines. Permits shall not be required for the following:
(a) Building Permit Exemptions:
1. […]
903.2.1.7 · Multiple Fire Areas. An automatic sprinkler system shall be
903.2.1.7 Multiple Fire Areas. An automatic sprinkler system shall be
provided where multiple fire areas of Group A-1, A-2, A-3 or A-4
occupancies share exit or exit access components and the combined occupant
load of these fire areas is 100 or more.
1. Agricultural and Greenhouse buildings as approved by the fire code
official when not required in other sections of the California Building
Code.
2. Detached accessory structures to Group R-3 not classified as a
dwelling unit and not exceeding 3,000 square feet (279m2) in gross
floor area.
3. Detached non-combustible motor vehicle fuel dispensing canopies.
4. […]
903.2.9 · Group S. An automatic sprinkler system shall be provided throughout
903.2.9 Group S. An automatic sprinkler system shall be provided throughout
all buildings containing a Group S occupancy where the gross floor area
exceeds 3000 square feet (279m2).
Exceptions:
1. Agricultural and Greenhouse buildings as approved by the fire code
official.
2. Detached accessory structures to Group R-3 not classified as a
dwelling unit and not exceeding 3,000 square feet (279m2) in gross
floor area.
3. Special occupancy aircraft shade structures as approved by the fire
code official, unless required in NFPA409.
4. […]
903.6 · Where required in existing buildings and structures. An automatic
903.6 Where required in existing buildings and structures. An automatic
sprinkler system shall be provided throughout existing buildings and
structures where required in Chapter 11 or that undergo a substantial
improvement or Substantial Damage as defined by CBC Chapter 2 in
accordance with Table 903.6.
Exception: Alterations made solely for the purpose of providing barrier
removal pursuant to the requirements of the American Disabilities Act (ADA)
as contained in exception #4 of Section CBC 11B-204.2.
16
Existing Gross Floor Area (d)
Allowable Gross Floor Area Increase
0-1,000 sq. ft.:
200% (c)
1,001-4,000 sq. ft.:
100% (a)(c)
Greater than 4,000 sq. […]
905.3.1 · Height. In other than Group R-3 and R-3.1 occupancies, Class III
905.3.1 Height. In other than Group R-3 and R-3.1 occupancies, Class III
standpipe systems shall be installed throughout at each floor where any of the
following occur:
1. Buildings where the floor level of the highest story is located more than 30
feet (9144 mm) above the lowest level of fire department vehicle access.
2. Buildings that are three or more stories in height.
3. Buildings where the floor level of the lowest story is located more than 30
feet (9144 mm) below the highest level of fire department access.
4. Buildings that are two or more stories below the highest level of fire
department vehicle access.
Exceptions:
a. […]
R403.1.6 · Foundation anchorage. Wood sill plates and wood walls supported
R403.1.6 Foundation anchorage. Wood sill plates and wood walls supported
directly on continuous foundations shall be anchored to the foundation in
accordance with this section.
Cold-formed steel framing shall be anchored directly to the foundation or
fastened to wood sill plates in accordance with Section R505.3.1 or R603.3.1,
as applicable. Wood sill plates supporting cold-formed steel framing shall be
anchored to the foundation in accordance with this section. […]
R309.2 · One- and two-family dwellings automatic fire sprinkler systems. An
R309.2 One- and two-family dwellings automatic fire sprinkler systems. An
automatic residential fire sprinkler system shall be installed in townhouses.
Group R-3 occupancies permitted under this code shall be provided throughout
regardless of square footage with an automatic sprinkler system inclusive of all
mobile homes, manufactured homes and multi-family manufactured homes with
two or more dwelling units in accordance with Title 25 of the California Code
of Regulations.
Exception:
(a) Accessory Dwelling Unit, provided that all of the following are met:
a.1. The unit meets the definition of an Accessory Dwelling Unit as
defined in the Government Code Section 65852.2.
a.2. […]
Q103.2.1 · New additions, alterations, and change of occupancy. New
Q103.2.1 New additions, alterations, and change of occupancy. New
additions, alterations, and change of occupancy to existing buildings shall
comply with the requirements of the California Building Standards Code
effective at the time of addition, alteration, or change of occupancy. The
requirements shall apply only to and/or within the specific area of the
addition, alteration, or change of occupancy.
Exceptions:
1. Existing buildings and structures used for emergency housing and
emergency housing facilities may not be required to comply with the
California Energy Code, as determined by the enforcing agency.
2. […]
Q110.3 · Toilet and bathing facilities. When dependent units are used as
Q110.3 Toilet and bathing facilities. When dependent units are used as
emergency housing, the emergency housing site shall be provided with one
toilet and one bathing facility for every 15 occupants of each gender. The
enforcing agency may permit different types and ratios of toilet and bathing
facilities. The approval shall be based upon a finding that the type and ratio of
toilet and bathing facilities are sufficient to process the anticipated volume of
sewage and waste water, while maintaining sanitary conditions for the
occupants of the emergency housing. […]
Mapped hazard and district overlays stack on top of the adopted code. These are the overlays recorded for Sonoma County. They apply by parcel, not jurisdiction-wide, so confirm the parcel before assuming one is in play. Check CAL FIRE's fire hazard severity viewer and FEMA's flood map service.
Very High Fire Hazard Severity Zone
FEMA mapped flood hazard area
State law that overrides local zoning here
When one of these applies, the state statute governs over a conflicting local standard. This is the most common reason a local rule someone quotes you turns out not to be enforceable against a project.
Gov. Code 66310 et seq.
State ADU law preempts local zoning that would preclude a conforming ADU/JADU.
Applies when: project includes an ADU or JADU
Gov. Code 65915
State Density Bonus Law concessions/waivers override local development standards.
Applies when: project requests a density bonus
Gov. Code 65852.21 / 66411.7
SB 9 urban lot split / two-unit ministerial approval preempts conflicting local standards.
Applies when: project is an SB 9 lot split or two-unit development
Sonoma County enforces 2025 CBC, T24 Pt 2 based on 2024 IBC, the edition adopted statewide in California, amended locally in 2 disciplines.
Does Sonoma County amend the California code?
Yes: building, zoning.
Where do I confirm the code edition for a Sonoma County permit?
With the county building department that will review the permit. Adoption ordinances are amended on a local schedule, and a set submitted days apart can fall under different editions during a changeover.
Knowing the adopted edition is the easy half. Architechtura reads your drawings, resolves which of these provisions actually apply to the project, and returns the corrections a plan checker would write up, each one cited to the section it came from.
Compiled from published state and municipal adoption ordinances. Local governments amend their codes on their own schedule, and a pending ordinance can change what applies to your permit. Confirm the governing edition with the building department before you submit. This page is reference information, not a code determination.