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ADU Builders in Fontana, CA

83 builders · ranked by Google rating and review volume · 41 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 Fontana 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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Fontana is home to about 208,393 people (2020 Census) in San Bernardino County. We found 83 ADU builders and contractors that show up for Fontana homeowners on Google Maps, 3 of them based in the city itself. Their average Google rating is 4.8 stars. 23 market themselves specifically as ADU builders, and 2 mention garage conversions. 41 have a matched, active CSLB license shown with a verified badge. The top-rated by our review-weighted score are JNC Construction, M.L. Construction and SouthSTAR Construction.

Lots across San Bernardino County are often larger and land costs lower, which makes detached and prefab ADUs attractive. Foothill and mountain areas can face wildfire-zone construction requirements.

#1

JNC Construction

5.0 (143 Google reviews)

9360 Base Line Rd Ste H, Rancho Cucamonga, CA 91701

Serves Fontana · based in Rancho Cucamonga
Remodels & additionsHome builderGeneral contractor
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#7

MDT, Inc

5.0 (32 Google reviews)

6744 Magnolia Ave, Riverside, CA 92506

Serves Fontana · based in Riverside
Remodels & additionsGeneral contractor
CallWebsiteView profile
#10

St Paul Contracting

5.0 (25 Google reviews)
✔ CSLB License Verified #1104071

9650 Business Center Dr Bldg 17, Suite 131, Rancho Cucamonga, CA 91730

Serves Fontana · based in Rancho Cucamonga
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#11

J.Peace Builders Inc

5.0 (24 Google reviews)
✔ CSLB License Verified #1073588

414 E Rialto Ave STE B, San Bernardino, CA 92408

Serves Fontana · based in San Bernardino
General contractor
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#15

Straight Edge Builders

4.9 (48 Google reviews)
✔ CSLB License Verified #1075936

301 9th St, Redlands, CA 92374

Serves Fontana · based in Redlands
Garage conversionsRemodels & additionsGeneral contractor
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#17

Khan Construction Co.

4.9 (37 Google reviews)
✔ CSLB License Verified #700519

5802 Aurora Ave, Jurupa Valley, CA 91752

Serves Fontana · based in Jurupa Valley
Home builderGeneral contractor
CallWebsiteView profile
#23

JJ.Builders

5.0 (11 Google reviews)
✔ CSLB License Verified #1157031

Service-area business · Norco

Serves Fontana · based in Norco
Remodels & additionsHome builderGeneral contractor
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#33

Kirmina Construction

5.0 (8 Google reviews)
✔ CSLB License Verified #1144144

8615 Mesa Oak Dr, Riverside, CA 92508

Serves Fontana · based in Riverside
Remodels & additionsHome builderGeneral contractor
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#44

The ADU Pro

4.7 (15 Google reviews)
✔ CSLB License Verified #1128679

15338 Central Ave, Chino, CA 91710

Serves Fontana · based in Chino
ADU specialistHome builderGeneral contractor
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#49

M.E.A Construction Inc.

5.0 (3 Google reviews)
✔ CSLB License Verified #1007006

1394 Via Vista Dr, Riverside, CA 92506

Serves Fontana · based in Riverside
Remodels & additionsHome builderGeneral contractor
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#53

OSHI Construction Inc.

5.0 (2 Google reviews)
✔ CSLB License Verified #990408

10722 Arrow Route Ste 304, Rancho Cucamonga, CA 91730

Serves Fontana · based in Rancho Cucamonga
Remodels & additionsHome builderGeneral contractor
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#54

RAW Construction & Design

5.0 (2 Google reviews)
✔ CSLB License Verified #1047610

9195 Peoria Ln, Moreno Valley, CA 92557

Serves Fontana · based in Moreno Valley
Home builderGeneral contractor
CallView profile
#55

USModular, Inc.

4.6 (39 Google reviews)

579 W County Line Rd, Calimesa, CA 92320

Serves Fontana · based in Calimesa
ADU specialistPrefab / modularHome builderGeneral contractor
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#57

R&R Improvements

4.6 (10 Google reviews)
✔ CSLB License Verified #1087664

16226 Windcrest Dr, Fontana, CA 92337

Based in Fontana
Remodels & additionsHome builderGeneral contractor
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#64

BCM Group Inc

4.0 (4 Google reviews)
✔ CSLB License Verified #968356

9339 Feron Blvd, Rancho Cucamonga, CA 91730

Serves Fontana · based in Rancho Cucamonga
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#71

ADU Makers

No rating yet (0 Google reviews)
✔ CSLB License Verified #1104137

3400 La Sierra Ave, Riverside, CA 92503

Serves Fontana · based in Riverside
ADU specialist
CallView profile
#74

Hidden Peak Homes

No rating yet (0 Google reviews)

473 E Carnegie Dr #200, San Bernardino, CA 92408

Serves Fontana · based in San Bernardino
Home builderGeneral contractor
CallView profile
#76

New ADU Home

No rating yet (0 Google reviews)

1702 Kippy Dr, Colton, CA 92324

Serves Fontana · based in Colton
ADU specialist
View profile
#77

Rocket ADU Solutions

No rating yet (0 Google reviews)

1881 Commercenter E #138, San Bernardino, CA 92408

Serves Fontana · based in San Bernardino
ADU specialistPrefab / modular
CallView profile
#80

Premier ADU

No rating yet (0 Google reviews)

Service-area business · Upland

Serves Fontana · based in Upland
ADU specialistGeneral contractor
CallWebsiteView profile

Permits and pre-approved plans in Fontana

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

Planning an ADU in Fontana? Start here

AB 1033: Can You Sell an ADU Separately in California?How to Legalize an Unpermitted ADU in California (AB 2533)Two-Story and Above-Garage ADUs in California: Height Rules, Costs and DesignSB 9 vs ADU: Lot Splits, Duplexes and Backyard Units in California

All ADU guides →

Fontana ADU FAQ

How many ADU builders serve Fontana?

Our directory lists 83 ADU builders and contractors that appear for Fontana on Google Maps, including companies based in nearby San Bernardino County communities.

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

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

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 Fontana 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 Bernardino County

San Bernardino 51Ontario 54Rancho Cucamonga 31Victorville 16Rialto 56Hesperia 18Chino 49Upland 27Chino Hills 117Apple Valley 17Redlands 20Highland 8
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