Your Trusted Source for ADU Information in California

What this site covers

Updated October 28, 2026. ADU Home Construction publishes free, researched guides for California homeowners who are thinking about an accessory dwelling unit. The writing is plain English. A page here is not a contractor's proposal, a permit approval, or legal advice about your lot. Read the guide, then confirm the current rule on the city's own ADU page and in the official source the guide cites.

If you are still deciding whether to build, start with why homeowners add an ADU. That page describes a separate small home for family or a renter, on a lot you already own. The planning guide is the next stop. It covers lot limits, detached and attached units, garage conversions, junior ADUs, and the state clocks for a complete application. The legal guide collects the statewide rules cities have to follow, with links into the Government Code for size, parking, and fees. Local checklists are not the same from town to town. The Orange County city guides are a starting sketch for Irvine, Anaheim, Santa Ana, Huntington Beach, and Newport Beach. Treat each city page as a map to that city's own ADU sheet, not as the permit.

Paying for the project is covered in the financing guide. The common tools are home equity, a cash-out refinance, and renovation or construction loans. The CalHFA ADU grant is not taking new applications, which the financing guide states from CalHFA's own page. The construction guide follows the build itself, from hiring to inspection. The prefab guide compares a factory-built unit with a unit built on the lot. Once the ADU is finished, the renting guide covers California rental basics for an ADU and a junior ADU, and the maintenance guide covers upkeep.

Shorter articles live on the blog. They include cost ranges labeled as planning estimates, garage conversions, junior ADUs, rental income, and permit timelines. The glossary defines the terms those pages use. Two free downloads sit next to the guides: the 2026 ADU eBook and the building checklist. Neither download is a bid or a loan approval.

Questions about a page, a correction, or a request to pass your city and project details along for a contractor introduction go through the contact form. We do not check licenses. Before you hire anyone, look the license up yourself at the Contractors State License Board. The contractor match form is the short version of that introduction request. We do not design the unit, pull the permit, or build it.