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ADU Builders in Montclair, CA

38 builders · ranked by Google rating and review volume · 20 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 Montclair 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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Montclair is home to about 37,865 people (2020 Census) in San Bernardino County. We found 38 ADU builders and contractors that show up for Montclair homeowners on Google Maps, 2 of them based in the city itself. Their average Google rating is 4.7 stars. 10 market themselves specifically as ADU builders, and 1 mention garage conversions. 20 have a matched, active CSLB license shown with a verified badge. The top-rated by our review-weighted score are JNC Construction, Skilled Home Builders and Hostetler Construction Inc..

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 Montclair · based in Rancho Cucamonga
Remodels & additionsHome builderGeneral contractor
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#5

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 Montclair · based in Rancho Cucamonga
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#8

Capy Construction

5.0 (15 Google reviews)
✔ CSLB License Verified #1120565

Service-area business · Walnut

Serves Montclair · based in Walnut
Remodels & additionsHome builderGeneral contractor
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#9

Lopez United Inc

5.0 (14 Google reviews)
✔ CSLB License Verified #841932

11991 Silicon Ave, Chino, CA 91710

Serves Montclair · based in Chino
Remodels & additionsHome builderGeneral contractor
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#11

Salem Builders

5.0 (13 Google reviews)

Service-area business · Montclair

Serves Montclair · based in Montclair
Remodels & additionsHome builderGeneral contractor
CallView profile
#20

H&H Construction

5.0 (4 Google reviews)
✔ CSLB License Verified #868003

120 W Dayton St, Upland, CA 91786

Serves Montclair · based in Upland
Remodels & additionsGeneral contractor
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#25

OSHI Construction Inc.

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

10722 Arrow Route Ste 304, Rancho Cucamonga, CA 91730

Serves Montclair · based in Rancho Cucamonga
Remodels & additionsHome builderGeneral contractor
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#26

BAM Construction Inc

5.0 (2 Google reviews)
✔ CSLB License Verified #952311

12345 Mountain Ave Unit N232, Chino, CA 91710

Serves Montclair · based in Chino
Remodels & additionsGeneral contractor
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#30

BCM Group Inc

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

9339 Feron Blvd, Rancho Cucamonga, CA 91730

Serves Montclair · based in Rancho Cucamonga
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#32

CalHome ADU

1.0 (1 Google reviews)

2540 Fulton Rd, Pomona, CA 91767

Serves Montclair · based in Pomona
ADU specialistGeneral contractor
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#33

Home Masters Int'l

3.9 (38 Google reviews)
✔ CSLB License Verified #1009476

9038 Hellman Ave, Rancho Cucamonga, CA 91730

Serves Montclair · based in Rancho Cucamonga
Remodels & additionsHome builderGeneral contractor
CallWebsiteView profile
#36

Ironbridge ADU

No rating yet (0 Google reviews)

Service-area business · Upland

Serves Montclair · based in Upland
ADU specialistPrefab / modularHome builder
CallWebsiteView profile
#37

Premier ADU

No rating yet (0 Google reviews)

Service-area business · Upland

Serves Montclair · based in Upland
ADU specialistGeneral contractor
CallWebsiteView profile

Permits and pre-approved plans in Montclair

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

Planning an ADU in Montclair? Start here

How to Choose an ADU Builder in Southern California: 15-Point ChecklistJADU vs ADU in California: Size, Rules, Cost and Which to BuildHow to Legalize an Unpermitted ADU in California (AB 2533)The ADU Permit Process in California: Step by Step (2026)

All ADU guides →

Montclair ADU FAQ

How many ADU builders serve Montclair?

Our directory lists 38 ADU builders and contractors that appear for Montclair on Google Maps, including companies based in nearby San Bernardino County communities.

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

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

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 Montclair 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 51Fontana 83Ontario 54Rancho Cucamonga 31Victorville 16Rialto 56Hesperia 18Chino 49Upland 27Chino Hills 117Apple Valley 17Redlands 20
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