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ADU Builders & Contractors in Westminster, CA

With 147 verified ADU contractors serving Westminster, CA, homeowners have plenty of options for their accessory dwelling unit project. Local contractors ready to help specialize in everything from design-build to permit navigation.

📊 ADU Quick Facts for Westminster

Avg. Cost/sqft

$197-$372

Permit Timeline

60-120 weeks

Max Size

1200 sqft

Setbacks

4ft sides

Top 147 ADU Contractors in Westminster

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#1DIAZ CONSTRUCTION CO

Westminster, CA

Diaz Construction CO — licensed ADU contractor in Westminster, CA. Detached ADU construction. 32+ years experience.

View Profile📞 (714) 328 0276
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#2HUYNH HUNG C P I

Westminster, CA

Huynh Hung C P I — licensed ADU contractor in Westminster, CA. Detached ADU construction. 32+ years experience.

View Profile📞 (714) 448 9315
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#3PRO BUILDERS ENTERPRISE INC

Westminster, CA

Pro Builders Enterprise Inc — licensed ADU contractor in Westminster, CA. Detached ADU construction. 6+ years experience.

View Profile📞 (714) 951 4077
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#4SO CAL BUILDER

Westminster, CA

SO Cal Builder — licensed ADU contractor in Westminster, CA. Detached ADU construction. 33+ years experience.

View Profile📞 (714) 658 6833
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#5A V PRO BUILDER INC

Westminster, CA

A V Pro Builder Inc — licensed ADU contractor in Westminster, CA. Detached ADU construction. 8+ years experience.

View Profile📞 (714) 893 6919
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#6MALLORY CONSTRUCTION CO

Westminster, CA

Mallory Construction CO — licensed ADU contractor in Westminster, CA. Detached ADU construction. 24+ years experience.

View Profile📞 (714) 495 0783
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#7DOAN THOMAS VAN

Westminster, CA

Doan Thomas Van — licensed ADU contractor in Westminster, CA. Detached ADU construction. 16+ years experience.

View Profile📞 (714) 504 9540
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#8NAVIGATOR CONSTRUCTION

Westminster, CA

Navigator Construction — licensed ADU contractor in Westminster, CA. Detached ADU construction. 7+ years experience.

View Profile📞 (714) 552 8257
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#9NGUYEN QUOC CONSTRUCTION

Westminster, CA

Nguyen Quoc Construction — licensed ADU contractor in Westminster, CA. Detached ADU construction.

View Profile📞 (714) 548 4771
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#10NGUYEN THAI HOA

Westminster, CA

Nguyen Thai Hoa — licensed ADU contractor in Westminster, CA. Detached ADU construction. 20+ years experience.

View Profile📞 (714) 454 6235
View All 147 Contractors →

💰 How Much Does an ADU Cost in Westminster?

Garage Conversion

$68,500 - $128,500

Converting existing garage to living space

Detached ADU

$147,000 - $322,000

New standalone unit (600-1,200 sqft)

Permit & Fees

$1,101 - $5,101

Plan check, permits, utility connections

* Costs vary based on size, finishes, site conditions, and contractor. Get quotes from multiple Westminster contractors to compare pricing.

❓ Frequently Asked Questions About ADUs in Westminster

How much does it cost to build an ADU in Westminster?▼
The average cost to build an ADU in Westminster ranges from $147,000 to $322,000, or approximately $197 to $372 per square foot. Garage conversions typically cost $68,500 to $128,500.
How long does it take to get an ADU permit in Westminster?▼
The ADU permit process in Westminster typically takes 60 to 120 weeks. California law requires cities to approve or deny ADU permits within 60 days of receiving a complete application.
What are the ADU size limits in Westminster?▼
In Westminster, detached ADUs can be up to 1200 square feet. Attached ADUs are limited to 50% of the primary dwelling or 1,200 sqft, whichever is less. Junior ADUs (JADUs) are limited to 500 sqft and must be within the existing home.
What is the setback requirement for ADUs in Westminster?▼
Westminster requires 4-foot setbacks from side property lines and 4-foot setbacks from rear property lines for new ADU construction. Converted structures (like existing garages) may maintain their current setbacks.
Do I need to provide parking for my ADU in Westminster?▼
No parking is required for ADUs in Westminster if your property is within half a mile of public transit, in a historic district, part of an existing multi-family building, or if the ADU is a garage conversion. Otherwise, one space may be required.

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