Is an ADU covered by your California homeowners policy?

No. The HO-3, a model homeowners form from the Insurance Services Office (ISO) that insurers can adapt, covers an attached unit and a detached one in different ways.

An ADU inside the house or attached to it is part of the dwelling. The 2011 form covers the house "including structures attached to the dwelling," so the unit shares the house's rebuild amount.

A junior ADU, which state law requires to be built within the walls of the house, falls in this group too.

A detached ADU, set apart from the house by clear space, is an "other structure," like a detached garage. The form caps that coverage at 10% of the house's rebuild amount.

You can raise that limit. The Department of Insurance's guide says "you may purchase more coverage for an additional premium."

That 10% is one limit for every detached structure, a garage or shed included. Add up what it would cost to rebuild the ADU and the rest. If the total tops 10% of your home's rebuild amount, ask for a higher other-structures limit.

A detached ADU can lose its coverage. The model form leaves out other structures "rented or held for rental" to someone who does not also rent the main house.

So if you live in the main house and rent the ADU to someone else, the building drops out. The form also leaves out an other structure used to run a business.

Ask your insurer whether it offers an add-on for a structure rented to others, or whether the ADU needs a landlord policy of its own.

Lost rent may go with it. The model form pays fair rental value only when "a loss covered under Section I" makes the rented part unfit to live in. So ask how lost ADU rent is covered.

Your ADU tenant's belongings are theirs to insure. The Department of Insurance's guide tells renters they "should consider purchasing renter's insurance" to protect their belongings.

Often not. Government Code Section 66323 lists four kinds of ADUs that cities and counties must approve. For those, state law requires any rental to be "for a term longer than 30 days."

Junior ADUs have had the same rule since January 1, 2026, under AB 1154 (Chapter 507, Statutes of 2025).

For other ADUs on a lot with a single-family home, a city or county "may require" rentals of "30 days or longer." AB 976 (Chapter 751, Statutes of 2023) set that wording, in effect since January 1, 2024. It now sits in Government Code Section 66315, after a 2024 law renumbered the state's ADU rules.

AB 976 also made permanent the state's ban on rules that make an owner live on a property with an ADU. A junior ADU that shares a bathroom with the house is the exception: the owner must live in the house or in the junior ADU. If you rent out both the house and the ADU, a landlord policy usually replaces the homeowners policy.

Your city or county may add rules of its own. The city-by-city insurance rules list which places ask for proof of coverage before they issue a permit.

Paying guests also change the insurance question, as the guide to Airbnb and homeowners policies explains.

It might, if it sits within 30 feet of the house and can burn. A state rule in effect since October 14, 2022 makes insurers that price wildfire risk credit wildfire safety work in their rates.

One credited step is the "removal or absence of combustible structures, including sheds and other outbuildings," within 30 feet of the building. The FAIR Plan's discount sheet, which applies to policies that take effect on or after November 15, 2025, lists a similar step.

Neither one names ADUs. Ask your insurer, in writing, how it treats an ADU within 30 feet of the house.

Insurers that price wildfire risk must also give you your wildfire risk score in writing, and you can appeal it.

The FAIR Plan comes after standard and specialty insurers, and its dwelling form treats an ADU much as the model form does. Edition CFP 00 01 (05/2026) covers structures attached to the dwelling as part of it.

For detached structures, you can draw as much as 10% of the dwelling limit in all, and anything paid that way reduces the dwelling limit. You can also list a structure on the declarations page with its own limit.

The form also leaves out a detached structure rented to someone who does not also rent the main house, the same rule as the model form. If your ADU is rented, ask a licensed agent how the Plan would cover it, and get the answer in writing.

The Plan writes no more than $3 million at one location, so the house, the ADU and everything else on the policy share that cap.

The Plan's policy also has no liability coverage, which matters once a tenant lives in the ADU.

Get each answer in writing, and keep it with the policy:

• Is the ADU covered as part of the house, or as a separate structure?
• Would the limit on the ADU pay to rebuild it?
• Is the ADU covered once a tenant moves in, and from what date?
• Is the rent I would lose after covered damage to the ADU included?
• Does my liability coverage apply to injuries in or around the ADU?
• Does an ADU within 30 feet of the house affect my wildfire discounts?