What can I do if my city's ADU rules conflict with California law?

State ADU law sets minimum standards that cities and counties cannot undercut, and a local ADU ordinance that fails to comply is void, so the state standards apply instead. If your city applies a rule you believe conflicts with state law, raise it in writing with the city, use the appeal process, and request technical assistance from HCD while your application is pending.

Why conflicting local rules do not control

• Noncompliant ordinances are void. Under Government Code section 66316, if a local ADU ordinance does not meet state requirements, it is null and void and the agency must apply the state standards until it adopts a compliant ordinance.
• Ordinances must go to HCD. Section 66326 requires agencies to send new ADU ordinances to HCD within 60 days of adoption. If HCD finds an ordinance noncompliant, the agency has up to 30 days to respond and must either amend it or adopt findings explaining why it complies. Since January 1, 2026, an ordinance that is not submitted on time, or whose agency does not respond to HCD's findings on time, is null and void. Section 66333.5 applies the same rule to JADU ordinances.
• No other local rule can block you. Section 66317(c) says no local ordinance, policy or regulation other than a compliant ADU ordinance can be the basis for delaying or denying an ADU permit.
• State-protected units get extra protection. For ADUs and JADUs approved under section 66323, agencies cannot impose objective development or design standards beyond those listed in that section.

Cities may be less restrictive than state law, so a local rule that gives you more than the state minimum is not a conflict.

Steps you can take

1. Ask the city to identify, in writing, the code section it is relying on.
2. Check HCD's Technical Assistance and Enforcement Letters Dashboard for letters HCD has sent your city.
3. If your application is found incomplete or denied, use the written appeal process every permitting agency must now provide.
4. Submit a request through HCD's ADU Portal. HCD has authority to enforce state ADU law and may notify the Attorney General of violations, but its handbook notes it may not follow up with an agency on a project when no application is pending.
5. Consider a land-use attorney if the dispute is not resolved.

What this means for your MEP plans and permit set

State ADU law controls zoning-type standards such as unit size, setbacks, height and parking. It does not exempt your project from the building, electrical, plumbing, mechanical and energy codes, and local amendments to those codes, such as energy reach codes, are a separate question from ADU zoning rules. Keep the two apart when you push back, and make sure your MEP plans fully meet the applicable codes so the dispute stays focused on the zoning issue. See California ADU requirements, how the ADU permit process works, and the California ADU permit guide. Confirm specifics with your planning department.

Sources: leginfo.legislature.ca.gov, leginfo.legislature.ca.gov, leginfo.legislature.ca.gov, leginfo.legislature.ca.gov, hcd.ca.gov.