California’s accessory dwelling unit rules continue to evolve, and homeowners throughout the San Fernando Valley may be wondering what the 2026 updates mean for a future ADU, garage conversion, or junior ADU. The California Department of Housing and Community Development (HCD) updated its statewide ADU Handbook in March 2026, while local permitting and property-specific requirements still remain important.
An ADU can create flexible space for long-term housing, multigenerational living, or other lawful residential uses. But every property is different. Before making plans based on a neighbor’s project or a contractor’s estimate, homeowners should confirm the current rules, permit history, utility needs, and site conditions that apply to their own parcel.
WHAT CHANGED IN THE 2026 CALIFORNIA ADU GUIDANCE?
HCD’s March 2026 ADU Handbook incorporates changes to State ADU Law that became effective January 1, 2026. The handbook is an educational resource explaining how state law addresses accessory dwelling units and junior accessory dwelling units, commonly called ADUs and JADUs.
State law generally aims to reduce unnecessary barriers and establish clearer, more objective review standards. However, an ADU project must still satisfy applicable building, fire, health, safety, utility, and local development requirements. The type of ADU, existing structures, parcel location, hillside conditions, and other site characteristics can affect the process.
Homeowners should use the updated handbook as a starting point—not as a substitute for written guidance from the agency reviewing a specific project.
START WITH THE PROPERTY, NOT THE FLOOR PLAN
An attractive floor plan does not confirm that it will work on a particular lot. Before paying for detailed design work, collect basic property information:
• Current zoning and parcel information
• Existing building permits and certificates of occupancy
• Lot dimensions, easements, setbacks, and recorded restrictions
• Location of utilities, sewer or septic systems, and service capacity
• Fire-access, grading, drainage, hillside, or hazard considerations
• Whether a garage or other structure was built and converted with permits
For properties within the City of Los Angeles, owners can review zoning information through ZIMAS and search available building records through the Los Angeles Department of Building and Safety (LADBS). Records should be interpreted carefully because online information may not answer every question about the legal use or condition of a structure.
UNDERSTAND THE DIFFERENT ADU OPTIONS
A detached ADU is separate from the primary residence. An attached ADU connects to the existing home, while a conversion ADU may use qualifying existing space, such as part of a garage or another permitted structure. A JADU is a smaller unit created within a proposed or existing single-family residence and follows its own requirements.
The best option depends on the parcel and the owner’s goals. A conversion may appear simpler, but existing structural, foundation, fire-separation, ceiling-height, plumbing, electrical, or energy-code conditions can change the scope and cost. New detached construction can offer design flexibility but may require more extensive site work and utility coordination.
CHECK THE LOCAL PERMIT PATH
HCD explains statewide requirements, but permits are processed locally. In the City of Los Angeles, LADBS provides plan-check and permit resources, building-record searches, permit-status tools, and an LA Accessory Dwelling Unit Program. Properties in Simi Valley, Altadena, or other jurisdictions may have a different reviewing agency and local procedure.
Ask the appropriate department which documents are required and whether the property is affected by special conditions. Obtain written clarification when an issue could materially affect the design. Owners may need assistance from qualified architects, engineers, contractors, surveyors, permit professionals, utility providers, or legal and tax advisers, depending on the project.
BUDGET BEYOND CONSTRUCTION
A realistic ADU budget should consider more than the building itself. Possible costs may include design, engineering, surveys, plan check, permits, utility upgrades, trenching, drainage work, demolition, site access, fire-safety improvements, finish selections, financing expenses, insurance changes, and contingency reserves.
Project estimates should identify what is included, excluded, or still unknown. Homeowners should also verify contractor licensing and insurance through the appropriate California agencies and avoid relying on promised rental income or property-value increases to justify a project. Market demand, operating costs, insurance, taxes, financing, and lawful rental restrictions can change the financial outcome.
BUYING OR SELLING A HOME WITH AN ADU
Buyers should ask for permits, approved plans, final inspection records, utility information, and any certificate of occupancy applicable to the additional unit. The presence of a kitchen, bathroom, or separate entrance does not by itself prove that a space is a legal ADU.
Sellers should organize records early and describe the property accurately. If an ADU or conversion lacks clear documentation, qualified professionals can help determine which records exist and what additional investigation may be appropriate. Material facts should be discussed with the professionals responsible for disclosures and transaction advice.
A PRACTICAL NEXT-STEP CHECKLIST
1. Define the intended use and approximate budget.
2. Confirm the property’s jurisdiction and review agency.
3. Obtain zoning, permit, and parcel records.
4. Read the current HCD ADU Handbook.
5. Ask the local agency about property-specific requirements.
6. Compare written proposals from qualified professionals.
7. Review financing, tax, insurance, and rental considerations separately.
8. Keep permits, contracts, approvals, inspections, and warranties organized.
LOCAL REAL ESTATE GUIDANCE
Whether you are evaluating a home with an existing ADU or considering how an ADU might fit your future plans, the first step is understanding the property and asking the right questions. EH WORLDWIDE REALTY helps buyers and sellers evaluate real estate opportunities across Sherman Oaks, Altadena, Chatsworth, Granada Hills, Porter Ranch, Simi Valley, West Hills, and the greater San Fernando Valley.
Explore our communities: https://www.mysfvhomes.com/communities
Request a home valuation: https://www.mysfvhomes.com/home-valuation
Contact EH WORLDWIDE REALTY: https://www.mysfvhomes.com/contact-us
This article is for general educational purposes only and is not legal, tax, financial, architectural, engineering, or construction advice. Regulations, interpretations, fees, and programs can change. Confirm current requirements with the responsible agencies and qualified professionals.
OFFICIAL SOURCES
California Department of Housing and Community Development — ADU Handbook, updated March 2026: https://www.hcd.ca.gov/building-standards/adu/handbook
California HCD — Accessory Dwelling Units and Junior Accessory Dwelling Units: https://www.hcd.ca.gov/housing-element/building-blocks/adu
Los Angeles Department of Building and Safety — Plan Check and Permit Resources: https://www.ladbs.org/services/core-services/plan-check-permit
Los Angeles City Planning — Housing and ADU Resources: https://planning.lacity.gov/plans-policies/initiatives-policies/housing
