What is the maximum ADU size allowed in Diamond Bar?

Detached ADUs in Diamond Bar can be up to 1200 square feet.

ADU Builders & Contractors in Diamond Bar, CA

Q: How much does it cost to build an ADU in Diamond Bar?

The average cost ranges from $148,000 to $323,000, or $198-373 per square foot.

Q: How long does it take to get an ADU permit in Diamond Bar?

The permit process typically takes 60 to 120 weeks in Diamond Bar.

With 159 verified ADU contractors serving Diamond Bar, 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 Diamond Bar

Avg. Cost/sqft

$198-$373

Permit Timeline

60-120 weeks

Max Size

1200 sqft

Setbacks

4ft sides

Top 159 ADU Contractors in Diamond Bar

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#1WANG HSU - DA

Diamond Bar, CA

Wang Hsu - DA — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 30+ years experience.

View Profile 📞 (626) 503 2888

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#2D A S BUILDER INC

Diamond Bar, CA

D A S Builder Inc — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 7+ years experience.

View Profile 📞 (909) 610 0485

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#3J K Z GROUP INC

Diamond Bar, CA

J K Z Group Inc — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction.

View Profile 📞 (626) 466 6693

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#4PADILLA'S GRADING AND PAVING

Diamond Bar, CA

Padilla'S Grading And Paving — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction.

View Profile 📞 (626) 664 9285

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#5TIAN QI

Diamond Bar, CA

Tian QI — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 13+ years experience.

View Profile 📞 (714) 269 4581

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#6CORNERSTONE CONSTRUCTION CO

Diamond Bar, CA

Cornerstone Construction CO — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 43+ years experience.

View Profile 📞 (909) 861 7978

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#7ACE PLUMBING CO

Diamond Bar, CA

Ace Plumbing CO — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 25+ years experience.

View Profile 📞 (909) 973 0227

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#8KO JONATHAN

Diamond Bar, CA

KO Jonathan — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 16+ years experience.

View Profile 📞 (714) 471 8036

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#9CHEN ICHIEN

Diamond Bar, CA

Chen Ichien — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction.

View Profile 📞 (909) 895 9690

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#10ZHOU LIANG

Diamond Bar, CA

Zhou Liang — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 12+ years experience.

View Profile 📞 (626) 780 3498

View All 159 Contractors →

💰 How Much Does an ADU Cost in Diamond Bar?

Garage Conversion

$69,000 - $129,000

Converting existing garage to living space

Detached ADU

$148,000 - $323,000

New standalone unit (600-1,200 sqft)

Permit & Fees

$1,105 - $5,105

Plan check, permits, utility connections

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

❓ Frequently Asked Questions About ADUs in Diamond Bar

How much does it cost to build an ADU in Diamond Bar?▼

The average cost to build an ADU in Diamond Bar ranges from $148,000 to $323,000, or approximately $198 to $373 per square foot. Garage conversions typically cost $69,000 to $129,000.

How long does it take to get an ADU permit in Diamond Bar?▼

The ADU permit process in Diamond Bar 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 Diamond Bar?▼

In Diamond Bar, 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 Diamond Bar?▼

Diamond Bar 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 Diamond Bar?▼

No parking is required for ADUs in Diamond Bar 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.

Also See ADU Contractors In

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