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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#1CENTURY 25 DEVELOPEMENT CO

Diamond Bar, CA

Century 25 Developement CO — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 19+ years experience.

View Profile 📞 (909) 802 9057

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#2M D B DESIGN ASSOCIATES

Diamond Bar, CA

M D B Design Associates — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 33+ years experience.

View Profile 📞 (818) 726 1879

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#3CMPG PROJECT MANAGEMENT

Diamond Bar, CA

Cmpg Project Management — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 15+ years experience.

View Profile 📞 (909) 860 1586

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#4ARKIUS INC

Diamond Bar, CA

Arkius Inc — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 32+ years experience.

View Profile 📞 (714) 883 8969

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#5D D Y IMPROVEMENT CORP

Diamond Bar, CA

D D Y Improvement Corp — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 17+ years experience.

View Profile 📞 (626) 532 6370

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#6PERSPECTIVE LANDSCAPING INC

Diamond Bar, CA

Perspective Landscaping Inc — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 37+ years experience.

View Profile 📞 (909) 598 5658

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#7MONAIR CONTRACTORS

Diamond Bar, CA

Monair Contractors — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 32+ years experience.

View Profile 📞 (909) 967 0067

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#8MCDONALD CONSTRUCTION

Diamond Bar, CA

Mcdonald Construction — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction. 20+ years experience.

View Profile 📞 (909) 524 7312

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#9EVERCRAFT CONSTRUCTION INC

Diamond Bar, CA

Evercraft Construction Inc — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction.

View Profile 📞 (818) 802 6688

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#10STL HOME BUILD INC

Diamond Bar, CA

Stl Home Build Inc — licensed ADU contractor in Diamond Bar, CA. Detached ADU construction.

View Profile 📞 (909) 348 2679

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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