Millions of California homeowners live in common interest developments governed by homeowners associations. For years, HOA CC&Rs were one of the most effective tools for blocking ADU construction—boards could cite architectural standards, density provisions, or blanket prohibitions in the governing documents to deny project approval. Assembly Bill 670, signed into law in September 2019 and effective January 1, 2020, changed that permanently. California Civil Code § 4751 now declares void any HOA rule that effectively prohibits or unreasonably restricts the construction or use of an ADU or Junior ADU on a single-family lot.
The Legal Framework: Civil Code § 4751
Civil Code § 4751 provides that "any provision of a governing document of a common interest development that either effectively prohibits or unreasonably restricts the construction or use of an accessory dwelling unit or junior accessory dwelling unit on a lot zoned for single-family residential use is void and unenforceable." This language has three critical components: it applies to all governing documents including CC&Rs, bylaws, and architectural guidelines; it voids provisions that "effectively prohibit"—meaning a facially neutral rule can be void if it functions as a prohibition in practice; and it voids provisions that "unreasonably restrict"—meaning restrictions short of a complete ban can also be voided if unreasonable in scope or effect.
What HOAs Can No Longer Do
Since the effective date of AB 670, homeowners associations cannot: prohibit ADUs in CC&Rs or architectural guidelines, even if those provisions were adopted before 2020; require HOA board approval as a prerequisite to applying for a city building permit for an ADU; impose a blanket moratorium on ADU construction throughout the development; cite density provisions in the CC&Rs to limit dwelling units below what state ADU law permits; require design standards so onerous that they make ADU construction economically infeasible; or impose height, setback, or size restrictions more restrictive than those permitted by state ADU law.
What HOAs Can Still Control
Civil Code § 4751 does not strip HOAs of all authority over ADU construction. HOAs retain the ability to impose reasonable architectural and aesthetic standards, provided those standards do not effectively prohibit ADUs or unreasonably restrict them. Permissible HOA restrictions include: requiring exterior materials to match or be compatible with the primary dwelling and neighborhood character; specifying roof pitch or roofing material types consistent with the development's architectural style; restricting paint colors to a palette consistent with the community's color scheme; requiring screening of mechanical equipment visible from common areas; and requiring a landscaping plan to maintain common area aesthetics.
Reading Your CC&Rs
Before assuming your HOA prohibits ADUs, read the CC&Rs carefully. Many HOA governing documents include a "compliance with law" provision stating that any provision conflicting with applicable law is automatically superseded by that law. If your CC&Rs include such a provision, the ADU prohibition may already be legally ineffective without any formal amendment. Even without a compliance-with-law provision, the Civil Code § 4751 preemption is automatic—it does not require the HOA to amend its documents. The CC&Rs may still say "no ADUs"—those words become legally meaningless as applied to single-family lots.
The Two-Track Approval Process
HOA approval and city building permit approval are two separate and independent processes. California law does not require you to obtain HOA approval before applying for a building permit. You can submit your permit application to the city directly without waiting for HOA action. Cities are required to process your ADU permit application ministerially—they cannot require evidence of HOA approval as a condition of issuing the permit. Even if your HOA refuses to respond or purports to deny your project, you can continue pursuing the building permit on the city track. If the city issues your permit, you have the legal right to build.
How to Handle HOA Resistance
Despite the legal clarity of Civil Code § 4751, some HOAs continue to resist ADU projects through delay tactics or outright refusal. Effective strategies for handling HOA resistance include: sending a demand letter citing § 4751 stating that the HOA restriction is void and requesting confirmation that the board will not interfere with your permit application; submitting your permit application to the city regardless and letting the ministerial process move forward independently; invoking the HOA's dispute resolution process (California law requires HOAs to offer internal dispute resolution before disputes can be litigated); and filing a complaint with the California Department of Real Estate, which has authority over HOA practices.
When to Involve an Attorney
If your HOA refuses to acknowledge that § 4751 voids your CC&Rs' ADU prohibition, or if the board takes retaliatory action such as recording a notice of violation, threatening fines, or attempting to obtain an injunction, the situation warrants legal advice. California ADU law is well-established and courts have consistently sided with homeowners when HOAs have attempted to enforce ADU prohibitions post-AB 670. An attorney familiar with HOA law and California ADU statutes can provide a demand letter, represent you in ADR, or pursue litigation if necessary.
HOA ADU Rights in Practice
The practical reality since AB 670 took effect is that most HOAs—once clearly informed of Civil Code § 4751—back down from explicit ADU prohibitions. The resistance that does persist tends to come in the form of unreasonable architectural review delays rather than outright prohibitions. Understanding your rights, communicating them clearly in writing, and proceeding with the city permit application on a parallel track are the most effective strategies for navigating HOA-governed ADU projects in California. Permit-ready architectural drawings that document compliance with the HOA's reasonable aesthetic standards—matching materials, compatible roof form, harmonious color palette—give the HOA board less leverage to object on architectural grounds.