Frequently Asked Questions

An ADU, or accessory dwelling unit, is a secondary home on the same lot as a primary residence. ADUs provide complete independent living facilities, including a kitchen, bathroom, and sleeping area. This definition means the unit must function fully independently from the primary home.

A JADU (junior accessory dwelling unit) is created within the existing walls of the primary home, while an ADU can be detached, attached, or converted from existing space. As of January 2026, JADUs are limited to 500 square feet maximum and allow efficiency kitchens. JADUs also require owner occupancy, whereas standard ADUs do not.

The most common ADU types are: detached units (separate structures in the backyard), attached units (additions to the primary home), conversion ADUs (using existing interior or accessory space), garage conversions (converting an existing garage), and JADUs (junior units within the primary home walls). Each type has different cost and timeline implications.

Generally yes, you can rent out a standard ADU under California state law. However, local cities can impose additional restrictions, so always check your local planning department's rules. JADUs have specific owner-occupancy requirements where at least one unit (primary home or JADU) must be owner-occupied.

ADU size limits depend on the type and your local city rules. State law sets a general framework: detached ADUs are typically allowed up to 1,200 square feet for multi-bedroom units, though local requirements can be different. Attached ADUs and conversions may have different limits. Check your local planning department for specific limits in your jurisdiction.

Government Code Section 65852.2 is the primary statewide ADU law. It creates a baseline framework that all California cities and counties must follow. The State Housing and Community Development Department (HCD) also publishes an official ADU Handbook that provides guidance on interpreting and applying this law.

State law requires ministerial approval for ADU applications that meet statutory requirements. Cities cannot impose discretionary review or deny applications based on discretionary factors. However, your application must still meet the specific requirements in state law and any qualifying local standards.

State law removed the general owner-occupancy requirement for standard ADUs, so you can typically build and rent out an ADU without living in either unit. However, JADUs still require owner occupancy—at least one of the two units must be owner-occupied. Always verify your local rules.

State law sets minimum setback requirements that cities cannot exceed. For detached ADUs, the minimums are generally 4 feet from side and rear property lines. Requirements vary by ADU type and local jurisdiction. Check your city's specific setback rules, as they may allow closer placement.

Yes, state law limits the fees cities can charge for ADUs. For ADUs under 750 square feet, fees are capped. For larger units, cities can charge proportional fees based on square footage. This protects homeowners from excessive development costs while allowing cities to recover some infrastructure impact.

SB 9 is a California law that allows property owners in single-family zones to create up to two primary dwelling units on a single lot, or to split the lot into two separate parcels. It also allows urban lot splits in certain circumstances. When qualifying conditions are met, local approval is ministerial, meaning the city cannot deny the application.

No, SB 9 and ADU law are separate pathways. SB 9 creates primary units (not accessory units), so both units on the property would be primary residences. ADU law creates a secondary unit on a single lot. The two laws serve different purposes and follow different approval processes.

Potentially yes, but they are separate legal processes that follow different requirements. You could theoretically use both to create two primary units under SB 9 and then add an ADU, but this depends on your specific property and local rules. Consult your local planning department about combining these approaches.

SB 9 only applies to properties in single-family residential zones in urbanized areas. Your property must meet specific statutory conditions, including lot size and configuration requirements. Not every property qualifies, so check your city's planning department to determine if your lot is eligible.

Yes, ADUs are subject to California's Title 24 Energy Code. Compliance is not optional—all new residential construction, including ADUs, must meet the current energy standards. This ensures your ADU meets baseline efficiency requirements for heating, cooling, and appliances.

The energy code version that applies is determined by your permit application date, not the construction date. As of January 1, 2026, the 2025 Title 24 standards apply to applications submitted from that date forward. Check your city's timeline to understand which standards will apply to your specific project.

Title 24 requirements affect multiple systems: HVAC (heating and cooling), insulation values, window performance, water heating, lighting efficiency, ventilation, and solar readiness. Meeting these standards affects design choices, material selection, and cost. Working with a qualified designer helps ensure compliance.

It is strongly recommended to work with an energy consultant or qualified designer. They prepare the CF-1R compliance documentation required for your permit, which demonstrates that your design meets Title 24 standards. This documentation is essential for the building department to approve your project.

ADU costs vary widely depending on type (detached, attached, conversion), location, site conditions, and scope of work. There is no single statewide cost number. Cost drivers include land preparation, utility connections, materials, labor, permits, and design fees. See our cost drivers page for more information on what impacts the final price.

State law sets a 60-day processing timeline for ADU applications, though actual timelines vary by city depending on workload and completeness of submittals. Some cities process permits faster; others may take longer if additional information is requested. Contact your local building department for their typical timeline.

Start by identifying which city or county has jurisdiction over your property. Then learn the statewide ADU basics and check your local planning department's ADU guidelines. Finally, define your goal—whether you want family housing, rental income, or flexible space—to help determine which ADU type makes sense for your situation.

Whether you need a licensed architect depends on your project scope and local requirements. Most ADU permit applications require design work from a licensed professional (architect or engineer). For simpler projects like garage conversions, some jurisdictions may allow design by qualified technicians. Check your local requirements.

No, while state law creates a statewide baseline, each city administers its own local rules. Cities set their own checklists, fee schedules, setback requirements, and processes. This means the same ADU type might have different costs, timelines, and requirements depending on your location.

Check your city's planning department website for an ADU-specific page or design guidelines document. Most cities have published their local ADU requirements and application procedures. California ADU Co. also publishes city-specific pages that summarize key differences and requirements by jurisdiction.

State law limits HOA ability to unreasonably restrict ADUs. However, HOA restrictions in your CC&Rs (covenants, conditions, and restrictions) may still apply. Review your CC&Rs carefully and consider consulting with a local real estate attorney to understand your specific situation and options.