LOCAL PLANNING RESEARCH • CALIFORNIA STARTING POINTS
ADU Rules & Permits: What to Verify Before You Design
Find the authority responsible for your property, separate state and local requirements, document parcel-specific constraints, and prepare the right questions before submitting plans.
CALIFORNIA LOCAL STARTING POINTS
Use the city process that actually applies to your parcel.
These are official-source routes, not substitute city ordinances or an exhaustive city directory. Confirm incorporated versus unincorporated jurisdiction first.
City of San Diego
Start with Development Services Information Bulletin 400. It separates ADU/JADU requirements, application materials, fees and online submission. Its January 2026 version flags Coastal Overlay differences: do not transfer a noncoastal example to a coastal parcel. Record your project type and overlay status before choosing the checklist.
City of Los Angeles
The current LADBS website lists separate 2026 announcements for ADU/JADU development standards (IB P/BC 2026-150) and unpermitted-unit permitting (IB P/BC 2026-161). For an existing unpermitted dwelling, start with the LADBS unpermitted-unit announcement and its linked bulletin. A new garage conversion and legalization of an existing dwelling are not interchangeable.
City of San José
For properties inside San José, use our San Jose ADU guide to organize the City’s Universal Checklist, ADU Ally contact, permit path, fee estimator, preapproved-plan option and AB 2533 legalization resources. Then verify the current forms and requirements on the City of San José’s official ADU hub.
City of Yuba City
For properties inside incorporated Yuba City, use our Yuba City ADU Planning & Permit Guide with Permit Planner jurisdiction checks to confirm City-versus-Sutter-County jurisdiction, review current size, height and setback standards, use Permit Planner, and understand the permit, utility and older-unpermitted-unit pathways.
City of Arroyo Grande
For properties inside Arroyo Grande, use our Arroyo Grande ADU Planning & Permit Guide to compare the City’s December 2025 rules, regional pre-approved plan program, permit timing, utilities and AB 2533 legalization pathway. Then verify the current forms and plan sets on the City of Arroyo Grande’s official ADU hub.
City of Morro Bay
For properties inside Morro Bay, use our Morro Bay ADU Coastal Planning & Permit Guide to check the City’s newly effective 2026 ADU rules, coastal-development layer, six pre-designed stock plans, permit path and current fee resources. Confirm the parcel-specific coastal and planning requirements before selecting a design.
City of Chico
For properties inside Chico, use our Chico ADU Planning Guide for pre-approved designs and the City-supported site-plan program. It explains the City’s 14 pre-approved plans, the newer $150 application pathway for grant-funded site-plan preparation, digital permit workflow, fee calculators, septic/well checks and AB 2533 legalization guidance.
City of Fresno
If the parcel is inside incorporated Fresno, use our Fresno ADU Planning, Free Plans & Permit Guide to compare the City’s five pre-approved plans, current 2025 ADU code, cost-estimator resource, direct Building Permit workflow, tiny-house-on-wheels option and ADU Hotline. Confirm City-versus-Fresno-County jurisdiction before applying local standards.
What should I save before submitting?
Keep the agency checklist and its date, applicable project pathway, parcel constraints, written fee estimate, submission receipt and unresolved questions. Use our permit worksheet with the California process guide. Verify the state baseline in the HCD handbook.
Source-routing check: September 3, 2026. This is not a parcel-level legal review.
THE SHORT ANSWER
An ADU can be allowed by law and still be difficult on a specific property.
State baseline
California State ADU Law creates a statewide baseline for qualifying ADUs and JADUs, including ministerial review, size protections, setback limits, permit timelines and fee rules. Start with the current HCD handbook, then verify the local and parcel-specific layer.
City or county rules
The permitting jurisdiction may control zoning, applications, objective standards, fees, building review, and the interpretation of local code.
Parcel-specific constraints
Utilities, easements, hazards, septic capacity, overlays, recorded restrictions, fire access, and existing work can change what is practical.
THE RULE CHECKLIST
Verify the provisions that most often change the design.
Allowed configurations
Detached, attached, interior, garage conversion, above-garage, multifamily-lot options, and the number of units allowed.
Size and bedrooms
Maximum floor area, percentage limits, minimums, bedroom-related standards, and measurement method.
Setbacks and placement
Front, side, and rear setbacks; separation from structures; lot coverage; open-space rules; and conversion exceptions.
Height and stories
Base height, roof form, second-story conditions, neighborhood overlays, and standards near transit or multifamily buildings.
Parking and access
Required spaces, exemptions, replacement parking, driveway access, fire apparatus access, and construction staging.
Occupancy and rental use
Owner-occupancy rules, long-term rental requirements, short-term rental limits, deed restrictions, and separate-sale restrictions.
Utilities and sanitation
Sewer or septic capacity, water service, electrical load, meters, connection charges, easements, and trenching.
Fire and life safety
Sprinklers, address visibility, emergency access, fire separation, smoke and carbon-monoxide alarms, and egress.
Fees and timing
Planning, building, impact, school, utility, and other charges; completeness review; corrections; expiration; and inspections.
THE PERMIT PATH
A typical sequence—adapt it to the reviewing jurisdiction.
- 01
Pre-screen the address
Confirm jurisdiction, zoning, overlays, parcel records, obvious site constraints, and the state-law layer.
- 02
Choose a realistic configuration
Compare the types that can fit the lot, intended resident, access, utilities, and budget.
- 03
Confirm submittal requirements
Obtain the current checklist before commissioning drawings or technical studies.
- 04
Prepare coordinated documents
Align architectural, structural, civil, energy, utility, and site information as required.
- 05
Submit, respond, and track scope
Record completeness notices, corrections, agency comments, revisions, approvals, conditions, and fees.
- 06
Build and close permits
Schedule required inspections, preserve approved plans and changes, complete agency sign-offs, and obtain final documentation.
PERMIT FILE
Documents commonly requested or worth preparing.
| Document or evidence | What it establishes | What to confirm |
|---|---|---|
| Site plan or survey | Boundaries, structures, access, dimensions, and proposed location | Required accuracy, survey standard, easements, and overlays |
| Architectural drawings | Floor plans, elevations, area, height, openings, and use | Required sheets, scale, code notes, and professional stamps |
| Structural information | Foundation, framing, connections, and existing-building work | Engineering scope and whether existing conditions require investigation |
| Energy documentation | Insulation, glazing, equipment, and applicable efficiency compliance | Jurisdictional forms and climate requirements |
| Utility evidence | Water, sewer/septic, electrical, gas, drainage, and service capacity | Agency approvals, meters, easements, connection points, and fees |
| Hazard or specialty reports | Flood, fire, coastal, soil, slope, trees, or environmental constraints | Which overlays apply and what professional review is required |
START WITH OFFICIAL SOURCES
Build a jurisdiction file before choosing a design.
Use the local-source starting points above and record the actual city or county responsible for your parcel. Follow the California permit-process guide for application stages and the permit worksheet to track your evidence.
This is planning guidance, not a parcel-level approval.
AVOIDABLE ERRORS
Permit mistakes that create preventable delay.
Using the mailing city
The postal address can differ from the planning jurisdiction. Verify incorporated versus unincorporated status.
Relying on an undated summary
Regulations and application procedures change. Save current official material and its review date.
Designing before utility review
Sewer slope, septic capacity, electrical service, water, and easements can reshape the project.
Assuming zoning is the only approval
Building, fire, public works, utilities, health, and specialty districts may also review the work.
Submitting mismatched plans
Conflicting dimensions, area calculations, structural scope, and utility routes trigger corrections.
Ignoring permit closeout
Inspections, approved revisions, agency sign-offs, and final documentation matter after issuance.
HOMEOWNER QUESTIONS
Understand what the permit process is actually deciding.
Who issues an ADU permit?
Usually a city or county planning and building authority, but other agencies may review fire access, utilities, septic, public works, or special hazards. Confirm the authority for the exact address.
Does state law override local ADU rules?
California State ADU Law sets minimum statewide protections, but cities and counties still administer objective local standards and parcel-specific review. The practical question is not whether state law or local law wins in the abstract; it is which local standards remain valid under current California law for your project and property.
Is a building permit the same as zoning approval?
No. Zoning or planning review addresses land use and development standards; building review addresses construction and safety codes. Some jurisdictions coordinate them in one application, while others use separate reviews.
Can I use a pre-approved ADU plan?
A pre-approved plan may reduce review of repeatable building elements, but the property still needs site adaptation, utility planning, foundation work, and confirmation of local eligibility and constraints.
How long does an ADU permit take?
California provides statutory ADU review timelines, but the homeowner’s total calendar time still depends on whether the application is complete, how quickly corrections are resolved, utility and specialty reviews, and property-specific conditions. Use the current California permit-process guide for the 15-business-day completeness checkpoint and 60-day review framework.
What if staff guidance conflicts with published rules?
Ask for the applicable citation or written interpretation, record the date and staff contact, and use the jurisdiction’s formal clarification or appeal process where appropriate. Qualified local counsel may be necessary for a material dispute.
WHAT TO DO NEXT
Turn rule research into a project-ready file.
SOURCES AND RESEARCH STANDARD
Primary sources first; local verification always.
For California projects, use the current California HCD ADU Handbook, the current California Legislative Information text for State ADU Law, and the adopted materials published by the city or county that has jurisdiction over the parcel. Keep state protections, local objective standards and property-specific constraints as three separate layers in your planning file.
This page provides general educational information—not legal, land-use, design, engineering, or permit advice. Rules may change after review. Verify the current law and application requirements with the authorities responsible for your property. Read our Editorial & Source Policy.