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ADU Builders in El Cajon, CA

22 builders · ranked by Google rating and review volume · 13 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 El Cajon 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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Located in San Diego County, El Cajon had a 2020 Census population of about 106,215. We found 22 ADU builders and contractors that show up for El Cajon homeowners on Google Maps, 8 of them based in the city itself. Their average Google rating is 4.7 stars. 5 market themselves specifically as ADU builders. 13 have a matched, active CSLB license shown with a verified badge. The top-rated by our review-weighted score are Johnny General Contractor ADU, Foremost Building Solutions LLC and So Cal Design Build, Inc (CustomADU.com).

San Diego was an early ADU adopter. Coastal-zone lots may need a coastal development permit, which state law now requires within 60 days, and transit-area lots often qualify for the 18-foot detached height allowance.

#9

Forge & Stone

5.0 (8 Google reviews)

Service-area business · El Cajon

Serves El Cajon · based in El Cajon
Remodels & additionsHome builderGeneral contractor
CallWebsiteView profile
#12

AE Design & Build

5.0 (6 Google reviews)
✔ CSLB License Verified #1112475

4124 N Bonita St, Spring Valley, CA 91977

Serves El Cajon · based in Spring Valley
Design-build
CallWebsiteView profile

Permits and pre-approved plans in El Cajon

ADU permits in El Cajon 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 El Cajon whether it has approved plans you can use. See our pre-approved plans guide and California ADU law summary.

Planning an ADU in El Cajon? Start here

SB 9 vs ADU: Lot Splits, Duplexes and Backyard Units in CaliforniaADU Rental Income and Property Taxes in California: What to ExpectThe ADU Permit Process in California: Step by Step (2026)How Long Does It Take to Build an ADU in Southern California?

All ADU guides →

El Cajon ADU FAQ

How many ADU builders serve El Cajon?

Our directory lists 22 ADU builders and contractors that appear for El Cajon on Google Maps, including companies based in nearby San Diego County communities.

Do I need a permit to build an ADU in El Cajon?

Yes. ADUs need a building permit from the City of El Cajon, 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 El Cajon?

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 El Cajon 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 San Diego County

San Diego 120Chula Vista 86Oceanside 56Escondido 110Carlsbad 67Vista 60San Marcos 66Encinitas 64La Mesa 41Santee 67National City 99Poway 49
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