Garage Conversion ADU

Garage Conversion ADUs in Orange County

Convert your existing garage into a legal, rentable living unit — designed, permitted and built end-to-end by a licensed Orange County team.

Get your free quote→ (949) 374-7980

A garage conversion turns the structure you already have into a fully permitted, self-contained home — usually the fastest, lowest-cost way to add a legal rental or family unit in Orange County. Here’s what’s involved, how the permitting works, and what it costs.

What a garage conversion involves

Turning a garage into a livable ADU means insulating the walls, floor and roof, adding code-compliant egress windows, and running new plumbing and electrical for a full kitchen and bathroom. We also handle the fire separation between the unit and your home, and finish it to the same standard as new construction.

Permits & legalization

California allows garage-conversion ADUs statewide, and most Orange County cities have streamlined the approval. We package and clear the full city submittal — including current parking-replacement rules and Title-24 energy compliance — so the finished unit is fully legal and on the books.

Cost & timeline

Because the shell, foundation and roof already exist, a garage conversion is typically the lowest-cost path to an ADU. The exact figure depends on size, finishes and how much new plumbing and electrical the unit needs — we give you a firm number after seeing the space. Most conversions are measured in months, not years.

★

Why build with L Square

Design, permits and construction under one roof. L Square is a licensed Orange County design-build team (CSLB #1095476). One contract covers architecture, engineering, city approvals and our own build crews — so your ADU moves on a fixed schedule from first drawing to final inspection, across Orange County and Los Angeles.

01 · Architect-grade design: Every unit is drawn around your lot, light and privacy.
02 · Permit-ready, OC-savvy: We know each city’s ADU rules and clear the approvals for you.
03 · Built once, built right: Our own crews deliver on a fixed schedule, foundation to finishes.

Licensed · Insured · Bonded · CSLB #1095476 · Orange County & Los Angeles

Frequently asked questions

Is a garage conversion cheaper than a detached ADU?

Usually, yes. Because the structure already exists, you’re not paying for a new foundation, framing and roof — so a garage conversion is typically the lowest-cost way to add a legal ADU. The final number depends on size, finishes and how much new plumbing and electrical the unit needs.

Do I lose required parking?

In most cases California’s ADU law means you do not have to replace the parking a garage conversion removes, though the details vary by city. We confirm the current requirement for your address and handle it as part of the permit.

Can I add a kitchen and bathroom?

Yes. A legal ADU has its own full kitchen, bathroom, private entrance and living space — adding them is part of every garage conversion we build.

How long does a garage conversion take?

It’s one of the faster ADU types because the shell is already there. Most projects run a few months from design through permits to move-in, depending on city timelines and scope.

Does it add rentable square footage legally?

Yes. Once permitted and finalled, the converted garage is a legal dwelling unit you can rent out, and the added livable square footage can also lift your property’s value.

Building an ADU in your Orange County city

ADU rules vary by city — we handle the specifics for your address. Statewide, California allows ADUs up to about 1,200 sq ft with 4-ft side and rear setbacks (CA HCD); your city may add its own details. For the statewide rules, see the CA HCD ADU Handbook.

Irvine ADU rules Anaheim ADU rules Santa Ana ADU rules Huntington Beach ADU rules ADU cost guide All areas we serve

Ready to start
your ADU?

Get a free, no-pressure quote from a licensed Orange County design-build team — and a plan drawn around your lot.