Permit guide · CaliforniaUpdated July 2026
The California ADU Permit Path, Step by Step (2026)
California ADU law is unusually favorable to homeowners: approval is ministerial, the clock is capped, and the biggest lot-standard objections are pre-empted by statute. This is the path from idea to permit, and the overlays that can still slow it down — as of July 2026.
Why "ministerial" is the whole game
A standard ADU is approved ministerially — the planner checks your plans against fixed objective standards and approves, with no public hearing, no discretionary design review, and no CEQA environmental review (Gov. Code § 66314). That is the difference between a permit you can count on and a project a neighbor can stall. It also means the rules are knowable up front: if your plans meet the objective standards, the city must approve.
The protections state law gives you
| Protection | What it means for your build | Citation |
|---|---|---|
| Ministerial approval | No hearing, no discretionary design review, no CEQA — objective standards only | Gov. Code § 66314 |
| 60-day clock | The city must act on a complete application within 60 days | Gov. Code § 66317 |
| 800 sq ft protection | At least an 800 sq ft unit is allowed — lot coverage, FAR, and open-space rules cannot block it | Gov. Code § 66321 |
| Impact-fee waiver | Units under 750 sq ft pay no development impact fees | Gov. Code § 66324 |
| No owner-occupancy requirement | You do not have to live on the property to build or rent a standard ADU | AB 976 |
California recodified its ADU statutes effective 2025; the section numbers above are the current Government Code citations. ADU law changes almost every legislative session — verify the live standards with your city before you rely on any single number.
The steps, in order
- Confirm feasibility. Check your lot against the objective standards — allowed size, 4 ft side and rear setbacks (the state floor), and height. The ADU Feasibility Calculator runs your city, type, and size against what the law guarantees.
- Design to the objective standards. A prefab or pre-approved plan set that already meets code moves fastest, because there is nothing discretionary to argue about.
- Submit a complete application. The 60-day clock only starts when the application is complete, so a clean, complete submittal is the single biggest lever on timeline (Gov. Code § 66317).
- Plan check and corrections. Even a ministerial review can come back with correction items; each round adds calendar time. This is where real-world timelines stretch well past 60 days.
- Permit issued, then build. With the permit in hand, foundation and site work begin; a factory unit is often being built in parallel.
- Inspections and final. Standard construction inspections through to a final sign-off and, if applicable, a certificate of occupancy.
Approval times across the cities we track run from about six weeks to six months — see the per-city timelines in the Bay Area Prefab ADU Index. The 60-day statutory clock is a floor on process, not a promise your whole project is done in 60 days.
The overlays that can still slow you down
State law pre-empts most local objections, but a few situations layer extra process on top. If any of these apply to your lot, budget more time and verify early:
- Coastal zone. Parcels in the Coastal Zone can still require a Coastal Development Permit under the Coastal Act, which adds its own review on top of the ADU approval.
- HOA rules. Under the Davis-Stirling Act, an HOA cannot flatly prohibit an ADU on a single-family lot, but it can impose reasonable standards. Read your CC and Rs and expect an architectural-review step.
- Historic districts. A designated historic property or district can trigger additional design review that a standard lot would not face.
- Fire. Lots in a Very High Fire Hazard Severity Zone or the wildland-urban interface can carry fire-sprinkler, defensible-space, and access requirements — verify with your fire district.
- Utilities and sewer. Separate connections, meter upgrades, or sewer-capacity charges can be the quiet cost driver; some agencies require a new lateral or a capacity fee even when planning approval is clean.
FAQ
Does the 60-day clock mean my ADU is approved in 60 days?
Not quite. The city must act on a complete application within 60 days (Gov. Code § 66317), but plan-check corrections restart real-world calendar time, and the clock only runs once your submittal is complete. Cities we track range from about six weeks to six months — see the index.
Do I have to live on the property to build an ADU?
No — owner-occupancy is not required for a standard ADU (AB 976). That is what makes ADUs viable for owners who want to rent both the main home and the unit. Verify with your city, as local rules and JADU exceptions differ.
Can my city block an 800 sq ft ADU on lot-coverage grounds?
No. Gov. Code § 66321 protects at least an 800 sq ft unit from lot-coverage, floor-area-ratio, and open-space limits. Above 800 sq ft, local standards can apply — confirm your city's ordinance for anything larger.
City guides
Alameda County
Marin County