Should We Buy a Home With an ADU or Room for Parents to Move In?

Some families want a parent close by and still want everyone to have their own front door. Others want space for a grown child, a caregiver, or a future option.

I'm Jeanette Nelson, a REALTOR® with Jeanette Nelson Real Estate, Keller Williams Realty, serving Orange County, Huntington Beach, Costa Mesa, Fountain Valley, and surrounding areas. I help families sort out what they actually need before we tour, so we look at homes that fit how your family plans to live.

California's Department of Housing and Community Development (HCD) publishes an ADU Handbook that explains state law. Here are the basics it describes:

• ADU. An attached or detached unit with complete, independent living facilities for living, sleeping, eating, cooking and sanitation, on a lot with a primary home. People also call these granny flats, in-law units or backyard cottages.
• JADU. A junior unit of no more than 500 square feet of interior livable space, contained entirely within a single-family home. It may have its own bathroom or share one with the main house.

That difference matters. A JADU is part of the main house. An ADU can be a separate building.

The HCD handbook covers several rules that can affect a family's plans:

• Permit timing. A permitting agency must approve or deny a complete ADU or JADU application within 60 days when there is an existing home on the lot.
• Owner-occupancy. A city generally cannot require the owner to live on the property for an ADU. For a JADU that shares a bathroom with the main house, owner-occupancy is required, and the owner lives in either the main home or the JADU.
• Rentals. A JADU cannot be a short-term rental, and if rented, the term must be longer than 30 days.
• Selling separately. A JADU cannot be sold separately from the main home.

State law changes often. HCD added an addendum to its handbook summarizing changes in effect on January 1, 2026, so check the current version or ask the city.

This is the step I never skip. A backyard unit or a converted garage is only a true ADU if it was permitted.

The City of Huntington Beach states that it reviews all ADUs and JADUs ministerially, without a discretionary hearing, and that development in the Coastal Zone may require a Coastal Development Permit. The city also offers an HB Pre-Approved ADU Plan for a 1-story, detached 490 square foot unit. You can read more on the city's Accessory Dwelling Units page, and the city lists (714) 536-5511 for questions.

Before you remove contingencies, we can:

1. Ask the seller for permits and final sign-offs for the unit.
2. Check the city's records for the address.
3. Have your inspector look closely at the unit, its utilities and its exits.

If you're buying in Costa Mesa or Fountain Valley, check with that city instead. Each city has its own process.

Sometimes. The HCD handbook notes that FHA and Freddie Mac policies allow ADU rental income to be included in qualifying income in some cases, and that Fannie Mae offers financing for buying a home with an existing ADU.

Each program has its own rules, and your lender decides how your file is treated. Ask early, before you write an offer, whether the unit's income can count and what documents they need. Never plan your budget around rental income that isn't confirmed.

If a parent will live in the unit rent-free, there may be no income to count at all. That's a family choice, and your lender should know about it up front.

The house is the easy part. The conversation is harder, and it's worth having before you tour:

• Who pays for what. Mortgage, utilities, repairs and property taxes.
• Whose name is on title. Talk with an attorney or CPA about how to hold title and any tax effects.
• Daily life. Meals, privacy, guests and shared spaces.
• Changing needs. Stairs, step-free entries and bathrooms that work later.
• A plan if things change. What happens if a parent needs more care, or someone moves out.

You may also want to read about timing a move-up with kids in school, how Huntington Beach, Costa Mesa and Fountain Valley compare, and, if you already own a home with a unit, selling a home with an ADU.

If your family is thinking about living together under one roof, or one lot, I'd love to help you plan what to look for. Call or text me at 714.366.8575 | DRE: 01397168, or contact me. Jeanette Nelson is a REALTOR® with Jeanette Nelson Real Estate, Keller Williams Realty, serving Orange County, Huntington Beach, Costa Mesa, Fountain Valley, and surrounding areas.