| Table of Contents |
| 1. What is an ADU? |
2. Benefits of Building a Permitted ADU in California |
| 3. The Role of Local Jurisdictions in Approving ADU Permits |
| 4. State vs. Local Control: What Homeowners Should Know |
| 5. FAQ |
What is an ADU?
An Accessory Dwelling Unit (ADU) is a self-contained residential unit built on the same lot as a primary home. Also known as granny flats, in-law suites, or backyard homes, ADUs have gained popularity across California as a response to the housing shortage. They typically feature a kitchen, bathroom, and separate entrance, making them ideal for long-term rental, multigenerational living, or guest accommodation.
Benefits of Building a Permitted ADU in California
Getting a permit for your ADU ensures:
✅ Legal Compliance: Avoid fines, stop-work orders, or demolition requirements.
✅ Increased Home Value: Permitted ADUs can boost resale prices and appraisal values.
✅ Rental Income: Legally rent out your unit without risk of eviction notices or code violations.
✅ Financing & Insurance Eligibility: Only permitted structures qualify for mortgage refinancing and coverage.
✅ Peace of Mind: Permits ensure the structure meets safety and building codes.
The Role of Local Jurisdictions in Approving ADU Permits
While California state law sets the framework for ADU development, local jurisdictions are responsible for reviewing, approving, and enforcing the details of your ADU project.
🏛️ 1. Zoning and Land Use Regulations
Each city or county has specific zoning rules:
Minimum lot sizes
Setback requirements
Maximum square footage
Height limitations
While state law overrides some local restrictions, cities can still impose design and placement standards within those limits.
📝 2. Building Permit Process
The local building department reviews:
Construction drawings
Engineering plans
Structural integrity
Utility connections
Fire safety compliance
Local officials also handle inspections during and after construction to ensure code compliance.
🔍 3. Design Standards
Cities can require:
Matching architectural styles
Landscaping improvements
Privacy measures for neighboring properties
These must be objective, not subjective, due to state ADU laws passed in recent years.
🚗 4. Parking Requirements
Local governments may require parking unless:
The ADU is within ½ mile of public transit
It's a garage conversion
It's located in a historic or architecturally significant district
🏗️ 5. Timeframes for Approval
State law mandates that local jurisdictions must approve or deny ADU permits within 60 days of receiving a complete application. Delays beyond this timeline can lead to automatic approvals.
State vs. Local Control: What Homeowners Should Know
| Category | State Law | Local Jurisdictions |
|---|---|---|
| Max ADU Size | Up to 1,200 sq. ft. | May restrict based on lot coverage |
| Parking Waivers | Required near transit | Can’t override state exemption |
| Setbacks | 4 ft side/rear | Cannot impose stricter rules |
| Design Aesthetics | Objective only | No subjective design denial |
| Permit Timelines | 60 days | Must comply |
