Can my HOA stop me from building an ADU in California?

Generally, no. California law makes HOA rules and CC&Rs void and unenforceable if they effectively prohibit or unreasonably restrict an ADU or JADU on a lot zoned for single-family use. Your HOA can still apply reasonable restrictions, such as objective design or material standards, as long as they do not make the ADU unreasonably expensive or impossible to build.

The statutes

Civil Code section 4751 covers governing documents and deed restrictions in planned developments, and section 714.3 covers any deed, contract or other instrument affecting real property. Both void provisions that effectively prohibit or unreasonably restrict an ADU or JADU that meets the state ADU or JADU statutes on a single-family-zoned lot. Both still allow reasonable restrictions, defined as restrictions that do not unreasonably increase the cost to construct, effectively prohibit construction, or extinguish the ability to build the unit. Since June 30, 2025, section 714.3 also says reasonable restrictions cannot include any fees or other financial requirements.

What HOAs can and cannot do, according to HCD

• Can: apply limited objective standards, within reason, such as specified materials, architectural style, or other design and aesthetic rules, if they are not more stringent than state ADU law.
• Cannot: delay review beyond the timeframes required of local agencies or otherwise significantly delay the ADU; require changes that would force substantial costs or abandonment of the project; require neighbors' approval; restrict placement so the ADU becomes infeasible; or impose standards that are not objective or not knowable before you apply.
• Cannot influence your permit. City and county ADU approval is ministerial, and HCD says that letting an HOA review an application as part of the permit process would violate state ADU law.

Practical steps

1. Read your CC&Rs and architectural guidelines and note any objective design standards.
2. Submit to your HOA's architectural review promptly and keep a record of dates and responses.
3. If the HOA blocks or stalls the project, HCD encourages you to contact your local agency and seek legal counsel.

What this means for your MEP plans and permit set

HOA design rules can touch the visible parts of MEP work: where an outdoor heat pump unit sits, how refrigerant lines run on the exterior, where a new meter or subpanel is mounted, and where roof penetrations and solar panels go. Settle those locations with your HOA early so the site plan and MEP sheets you submit to the city match what the HOA accepts, and you are not revising plans in the middle of plan check. See ADU setbacks, how solar appears on electrical plans, and California ADU requirements. HOA disputes depend on the facts and your documents; this is general information, not legal advice.

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