What is the maximum ADU size allowed in Costa Mesa?

Detached ADUs in Costa Mesa can be up to 1200 square feet.

ADU Builders & Contractors in Costa Mesa, CA

Q: How much does it cost to build an ADU in Costa Mesa?

The average cost ranges from $150,000 to $380,000, or $300-550 per square foot.

Q: How long does it take to get an ADU permit in Costa Mesa?

The permit process typically takes 4 to 10 weeks in Costa Mesa.

Costa Mesa has launched a Safe ADU Legalization Program under AB 2533 to help homeowners with unpermitted units come into compliance, alongside streamlined permitting for new ADU construction.

📊 ADU Quick Facts for Costa Mesa

Avg. Cost/sqft

$300-$550

Permit Timeline

4-10 weeks

Max Size

1200 sqft

Setbacks

4ft sides

View Costa Mesa Planning Department →

Top 426 ADU Contractors in Costa Mesa

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#1D H K CONSTRUCTION & MANAGEMENT INC

Costa Mesa, CA

D H K Construction & Management Inc — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 27+ years experience.

View Profile 📞 (888) 528 0666

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#2BATH KITCHEN RENEW CONSTRUCTION

Costa Mesa, CA

Bath Kitchen Renew Construction — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 6+ years experience.

View Profile 📞 (714) 850 4660

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#3PACIFIC LANDMARK INC

Costa Mesa, CA

Pacific Landmark Inc — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 52+ years experience.

View Profile 📞 (949) 339 4953

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#4J T BUILDERS

Costa Mesa, CA

J T Builders — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 37+ years experience.

View Profile 📞 (949) 293 3997

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#5WENEEDA PLUMBER

Costa Mesa, CA

Weneeda Plumber — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 34+ years experience.

View Profile 📞 (949) 548 9884

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#6ASW CONSTRUCTION & DESIGN INC

Costa Mesa, CA

Asw Construction & Design Inc — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 7+ years experience.

View Profile 📞 (909) 276 0165

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#7CARREON SETH M

Costa Mesa, CA

Carreon Seth M — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 17+ years experience.

View Profile 📞 (310) 345 9021

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#8U S A BUILDERS

Costa Mesa, CA

U S A Builders — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 6+ years experience.

View Profile 📞 (949) 777 6516

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#9NIEBUHR CO THE

Costa Mesa, CA

Niebuhr CO The — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 32+ years experience.

View Profile 📞 (949) 244 7870

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#10KOUSTIK CLIFF

Costa Mesa, CA

Koustik Cliff — licensed ADU contractor in Costa Mesa, CA. Detached ADU construction. 18+ years experience.

View Profile 📞 (714) 240 4568

View All 426 Contractors →

💰 How Much Does an ADU Cost in Costa Mesa?

Garage Conversion

$75,000 - $185,000

Converting existing garage to living space

Detached ADU

$150,000 - $380,000

New standalone unit (600-1,200 sqft)

Permit & Fees

$4,000 - $12,000

Plan check, permits, utility connections

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

❓ Frequently Asked Questions About ADUs in Costa Mesa

How much does it cost to build an ADU in Costa Mesa?▼

The average cost to build an ADU in Costa Mesa ranges from $150,000 to $380,000, or approximately $300 to $550 per square foot. Garage conversions typically cost $75,000 to $185,000.

How long does it take to get an ADU permit in Costa Mesa?▼

The ADU permit process in Costa Mesa typically takes 4 to 10 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 Costa Mesa?▼

In Costa Mesa, 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 Costa Mesa?▼

Costa Mesa 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 Costa Mesa?▼

No parking is required for ADUs in Costa Mesa 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

Los Angeles (3215)San Diego (2582)San Francisco (2170)Sacramento (1551)Riverside (925)Fresno (904)Anaheim (784)Irvine (760)

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