ADU Pass
Santa Rosa
Sonoma County portion
Also in: No County
ADU Pass helps homeowners in Santa Rosa, Sonoma County, California navigate the permit paperwork for building an accessory dwelling unit. This area covers 6 ZIP codes.
Map
ADU details
ADU legality: allowed
Santa Rosa's ADU policy operates against the backdrop of the 2017 Tubbs Fire (which destroyed 1,000+ Coffey Park homes) and subsequent rebuilding programs. The city operated a Resilient City Permit Center post-fire with 5-day turnaround targets, which informed broader permit-process reform. Coffey Park is now ~96-97% rebuilt.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $1,500 | $67,500 | $69,000 |
| 600 | 600 | $1,500 | $270,000 | $271,500 |
| midpoint | 675 | $1,500 | $303,750 | $305,250 |
| 1000 | 1,000 | $6,500 | $450,000 | $456,500 |
Fee breakdown (as of 2026-04)
Permitting process
Viability (permitted uses)
- Long-term rental: yes Long-term rental (30+ days) explicitly permitted; AB 976 permanently removed owner-occupancy requirement effective 2024-01-01.
- Short-term rental: no California Government Code §65852.2(a)(6) prohibits cities from approving STR (under 30 days) use of ADUs; Santa Rosa enforces (Santa Rosa also has its own restrictive STR ordinance for primary dwellings).
- Office rental: with-restrictions Detached commercial office rental to outside tenants is not a permitted ADU use; ADUs are residential. Home occupation by the property owner is allowed.
- Home office: yes Home occupation permitted under Santa Rosa Zoning Code with restrictions on signage, employees, and customer traffic.
- Studio / workshop: yes Personal artist/maker studio is a permitted accessory use of an ADU.
- Agriculture: with-restrictions Limited urban agriculture and small-animal keeping permitted in single-family zones per Santa Rosa Zoning Code; Sonoma County's wine-country agricultural identity is more permissive in unincorporated areas.
- Relative support: yes Family-occupancy ADU explicitly permitted; no relationship requirement under California state law.
Incentives
Contacts
Utilities
- Water: City of Santa Rosa Water Department (Santa Rosa Water) · 30d connect
Santa Rosa Water (city-owned) provides retail water to the city. Connection fees waived for internal conversions and ADUs ≤750 sqft per Santa Rosa policy aligned with state SB 13 framework. - Sewer: City of Santa Rosa Utilities — Laguna Wastewater Treatment Plant · 30d connect
City operates the Laguna Wastewater Treatment Plant. Sewer connection fees waived for internal conversions and ADUs ≤750 sqft. - Electric: Pacific Gas & Electric (PG&E) for distribution; Sonoma Clean Power as default community-choice retail provider · 45d connect · $1,800
PG&E is the distribution utility; Sonoma Clean Power (CCA) is the default retail electric provider with 100% renewable options. PG&E service-upgrade lead times have been a chronic statewide bottleneck adding 30-90+ days for ADUs requiring panel upgrades. - Gas: Pacific Gas & Electric (PG&E) · 30d connect · $1,500
PG&E gas service throughout Santa Rosa. Title 24 2025 incentivizes all-electric ADU designs to skip gas connection.
Property values & taxes
Construction timeline
Realistic total: best 8mo · typical 13mo · worst 19mo
Sonoma County contractor market is tight due to ongoing Tubbs/Glass/LNU fire rebuild demand. PG&E electric service-upgrade lead times can extend total timeline materially.
Modular pathway inspectors are experienced with modular
Financing
State ADU loans:
- CalHFA ADU Grant Program up to $40,000
- HCD ADU Funding index
Insurance impact
HOA prevalence & preemption
Santa Rosa's HOA prevalence concentrated in newer master-planned subdivisions (Fountaingrove, Skyhawk, Annadel Heights) and post-Tubbs rebuilds. California's AB 670 / AB 3182 Davis-Stirling preemption voids any HOA covenant prohibiting ADUs on single-family lots; residual HOA design-standards authority remains.
Regulatory overlays (3)
- wui-fire-zone
Substantial Wildland-Urban Interface (WUI) exposure across Santa Rosa, particularly in Fountaingrove and along the eastern hillside boundary. CAL FIRE FHSZ (Very High Fire Hazard Severity Zone) covers significant portions of north and east Santa Rosa. ADUs in FHSZ require Chapter 7A WUI compliance: ignition-resistant exterior materials, ember-resistant vents, tempered/dual-pane glazing, fire-resistant decking, defensible-space landscaping. Tubbs Fire 2017 destroyed 1,000+ Santa Rosa homes; Glass Fire 2020 added impact. - seismic-retrofit-zone
Rodgers Creek Fault runs through Santa Rosa; Hayward-Rodgers Creek system with high seismic risk. ASCE 7-22 Seismic Design Category D applies. Standard CRC seismic detailing required; some sites may need geotechnical investigation. - flood-zone
Santa Rosa Creek and Mark West Creek corridors create FEMA SFHA exposure in parts of Santa Rosa. Properties in Zone AE require flood-elevation certificates.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
- Amendment
Contractor market (aggregate)
Legal history (timeline)
Current ordinance: Santa Rosa Zoning Code §20-42.130 — Accessory Dwelling Units (within Chapter 20-42 Standards for Specific Land Uses), adopted 2018-03-13, last amended 2020-12-15
- 2017-10-08 — Tubbs Fire — destruction of Coffey Park and Fountaingrove neighborhoods (city-ordinance)
Tubbs Fire ignited 2017-10-08 and destroyed more than 1,000 Santa Rosa homes in Coffey Park alone, plus extensive damage in Fountaingrove and other neighborhoods.
Effect: Triggered creation of the Resilient City Permit Center with 5-day permit turnaround targets for fire recovery. Reframed Santa Rosa's housing-policy environment around rebuilding and infill-housing capacity, which substantially shaped subsequent ADU policy. - 2018-03-13 — Santa Rosa initial post-fire ADU code update (city-ordinance)
Council-adopted post-Tubbs Fire ADU ordinance amendments to expand by-right ADU permitting and enable rebuilding flexibility.
Effect: Streamlined ADU approval in single-family zones and made it easier for Tubbs-Fire-impacted homeowners to add ADUs while rebuilding primary dwellings. Established 5-day Resilient City Permit Center turnaround target for fire-recovery permits including ADUs. - 2020-12-15 — Santa Rosa ADU 2020 ordinance — AB 68/AB 881/SB 13 conformance (city-ordinance)
Comprehensive update of Santa Rosa Zoning Code §20-42.130 to align with 2020 California ADU statewide overhaul.
Effect: Codified by-right ministerial ADU track, prohibited impact fees on ADUs <750 sqft, set 4-foot side/rear setbacks, and aligned size standards (850 sqft 1-BR / 1,000 sqft 2-BR). - 2025-03-15 — Coffey Park corridor rebuild — ongoing post-Tubbs infill activity (city-ordinance)
Continued Coffey Park reconstruction with city-led infill and ADU-friendly rebuild policies; Coffey Park ~96-97% rebuilt by 2026.
Effect: Sustained capacity in Santa Rosa's permit center for rebuild work has indirectly accelerated typical ADU plan-check time and built planning-staff familiarity with ADU site-work issues.
Known issues (3)
- other — Substantial CAL FIRE Very-High FHSZ coverage in Fountaingrove, Hidden Valley, and eastern hillside areas requires Chapter 7A WUI-compliant materials adding $20,000-$60,000 to ADU project cost vs. valley-floor sites. Many homeowners' insurance carriers have non-renewed Santa Rosa hillside properties; FAIR Plan is the fallback.
- other — PG&E electric service-upgrade lead times have been a chronic statewide bottleneck (including Santa Rosa) routinely adding 30-90+ days for ADUs requiring panel upgrades.
- other — Sonoma County contractor market is tight due to ongoing fire-rebuild demand (Tubbs 2017, Glass 2020, LNU 2020); ADU specialist contractor lead times run 5-7 months.
Sonoma County — county ADU rules and overlays
County ADU ordinance
California state — ADU law and programs
State ADU law
California has the most aggressive statewide ADU preemption regime in the US, built from ~15 bills passed 2019-2025 and enforced by the Department of Housing and Community Development (HCD). The 2026 HCD ADU Handbook addendum (in effect with the 2025 Title 24 code cycle) is the operative state-level reference. The regime does four things at once: (1) preempts local zoning that would ban or unreasonably restrict ADUs; (2) imposes by-right ministerial approval with short statutory deadlines; (3) caps fees and utility-connection charges; and (4) empowers HCD to void non-compliant local ordinances.
State HOA preemption
California has the strongest statewide HOA-preemption regime in the US for accessory dwelling units, built from two bills: AB 670 (2019) voided ADU-prohibiting covenants on single-family residential lots, and AB 3182 (2020) extended and codified the preemption into the Davis-Stirling Common Interest Development Act (Civil Code §§ 4740 / 4741). The combination prohibits common-interest communities from banning ADUs, restricting rentals below 25% of separate interests, or treating ADUs as separate HOA interests. Limits remain: HOAs retain authority over reasonable design standards and statutory height limits, and the 2026 Carlsbad case (CalMatters coverage) established that an HOA's documented design-standards regime can effectively delay or constrain ADU approval short of outright prohibition.
State financing programs
California's flagship state-level ADU financing program — the CalHFA ADU Grant Program — is paused and has not been refunded since the original $100 million allocation was fully deployed 2023-12-28. The program provided up to $40,000 per qualifying homeowner for pre-construction and non-recurring closing costs and financed approximately 2,500 ADUs in two rounds. As of 2026-04, no new funding round has been announced in the state budget. CalHFA continues to publish anti-scam warnings because bad actors actively solicit homeowners claiming access to grant funds that no longer exist. State-level financing activity has shifted to local pilot programs (San Francisco, San Jose, Los Angeles, San Diego) and private financing products (Fannie Mae ADU mortgage, HELOC, construction-to-permanent).
State housing programs
California's state-level ADU programs are concentrated at HCD (technical guidance, ordinance review, enforcement) and the paused CalHFA grant pipeline (covered under stateFinancing). The state does not operate a central pre-approved ADU plan library — instead, AB 1332 (2024) created a preemption framework for local pre-approved plans with a 30-day ministerial-approval deadline, and major cities (Los Angeles, San Diego, San Jose, Sacramento, Berkeley) have rolled out their own plan catalogs. The California YIMBY coalition and other housing-policy organizations play an influential role in bill drafting; they are not state agencies but effectively drive much of the ADU legislative agenda. The Title 24 code cycle (now 2025, in effect for 2026 permits) is the authoritative building-code baseline.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Codes
- 95401
- 95403
- 95404
- 95405
- 95407
- 95409
Post Office
- 2585 Sebastopol Rd, 95407
- 2850 Mcbride Ln, 95403
- 707 Hahman Dr, 95405
- 730 2nd St, 95404