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ADU Builders in Downey, CA

28 builders · ranked by Google rating and review volume · 17 CSLB license verified

★ Featured ADU builder

Featured ADU builder — this spot is open

Put your ADU company at the top of this page, in front of Downey homeowners who are comparing builders right now. Includes your logo, project photos, a direct call button and a link to your website.

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With roughly 114,355 residents at the 2020 Census, Downey is one of Los Angeles County's established communities. We found 28 ADU builders and contractors that show up for Downey homeowners on Google Maps, 8 of them based in the city itself. Their average Google rating is 4.9 stars. 9 market themselves specifically as ADU builders, and 3 mention garage conversions. 17 have a matched, active CSLB license shown with a verified badge. The top-rated by our review-weighted score are Domus Design Build, Hybrid Renovations and Latin Construction Group Inc.

Los Angeles leads California in ADU permits. Common projects here include garage conversions on older lots, detached backyard units on deep lots, and hillside sites where access and grading drive the cost.

#2

Hybrid Renovations

4.9 (162 Google reviews)
✔ CSLB License Verified #1134177

10350 Heritage Park Dr Ste 204, Santa Fe Springs, CA 90670

Serves Downey · based in Santa Fe Springs
Remodels & additionsGeneral contractor
CallWebsiteView profile
#5

Rockwood Remodels

5.0 (17 Google reviews)
✔ CSLB License Verified #934419

10017 Walnut St, Bellflower, CA 90706

Serves Downey · based in Bellflower
Remodels & additionsHome builder
CallWebsiteView profile
#6

Ga Design Build

4.9 (29 Google reviews)

16226 Clark Ave, Bellflower, CA 90706

Serves Downey · based in Bellflower
Design-buildRemodels & additionsHome builderGeneral contractor
CallWebsiteView profile
#21

XactBuilt ADU & Construction

5.0 (4 Google reviews)
✔ CSLB License Verified #1092832

11721 Whittier Blvd suite 170, Whittier, CA 90601

Serves Downey · based in Whittier
ADU specialistRemodels & additionsHome builderGeneral contractor
CallWebsiteView profile
#27

Expert Home Builders

4.4 (304 Google reviews)
✔ CSLB License Verified #1056600

5800 S Eastern Ave Suit 500, Commerce, CA 90040

Serves Downey · based in Commerce
Home builderGeneral contractor
CallWebsiteView profile

Permits and pre-approved plans in Downey

ADU permits in Downey go through the city's building or planning department. Under AB 1332, every California city and county had to set up a pre-approved ADU plan program by January 1, 2025, so ask Downey whether it has approved plans you can use. See our pre-approved plans guide and California ADU law summary.

Planning an ADU in Downey? Start here

Prefab and Modular ADUs in California: Real Costs, Permits and PitfallsJADU vs ADU in California: Size, Rules, Cost and Which to BuildGarage Conversion ADU Cost in Southern California (and What Drives It)How to Choose an ADU Builder in Southern California: 15-Point Checklist

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Downey ADU FAQ

How many ADU builders serve Downey?

Our directory lists 28 ADU builders and contractors that appear for Downey on Google Maps, including companies based in nearby Los Angeles County communities.

Do I need a permit to build an ADU in Downey?

Yes. ADUs need a building permit from the City of Downey, which must approve or deny a complete application within 60 days under state law. Many cities also offer pre-approved plans that speed up review.

How much does an ADU cost in Downey?

Most Southern California detached ADUs land around $350 to $550 per square foot all-in, garage conversions around $200 to $350, and JADUs around $50,000 to $150,000. Use our ADU cost estimator and get three itemized bids.

How are Downey ADU builders ranked here?

By Google rating weighted by the number of reviews, so a 4.9 with 200 reviews ranks above a 5.0 with 3. Featured placements are clearly labeled and don't affect the organic ranking.

Nearby cities in Los Angeles County

Los Angeles 118Long Beach 119Santa Clarita 27Glendale 117Lancaster 12Palmdale 12Pomona 67Torrance 98Pasadena 100West Covina 68El Monte 24Inglewood 46
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