ADUs (Accessory Dwelling Units) are one of the best investments for California homeowners. Here's what they actually cost to build, from simple garage conversions to custom detached units.
Garage Conversion ADU Costs
Converting an existing garage to an ADU typically costs $100,000-180,000 in Southern California. This includes foundation work, utilities, bathroom/kitchen, HVAC, and finishes. Two-car garages converting to larger ADUs run $150,000-250,000.
Detached ADU Construction
Ground-up detached ADUs cost $200,000-400,000 depending on size and finishes. A basic 400 sq ft studio ADU might cost $180,000-250,000. A full 1,200 sq ft two-bedroom ADU typically runs $300,000-450,000.
Permits & Fees
California ADU permits have been streamlined but still cost $5,000-15,000 in fees. Design and engineering add $8,000-20,000. Total soft costs typically run 15-20% of construction cost.
Return on Investment
ADUs in Southern California can generate $1,500-3,500/month in rental income. Many homeowners recover construction costs within 8-15 years while adding 25-35% to property value.
Final Thoughts
ADUs represent one of the best investments for California homeowners. Despite high upfront costs, the combination of rental income and property value increase makes them financially compelling.
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Frequently Asked Questions
Do I need permits for an ADU?
Yes, all ADUs require permits. California has streamlined the process, but permits remain mandatory for legal units.
Can I rent my ADU?
Yes. California law allows ADU rentals for terms of 30+ days. Some cities now allow short-term rentals as well.
How long does ADU construction take?
Garage conversions typically take 3-5 months. Detached ADUs take 6-10 months from permit to completion.
Topics
- adu
- cost guide
- california
- garage conversion
- guest house
- rental income
About the author
Remodel Your Vibe Design Team
Written by the design team at Remodel Your Vibe, a licensed (CSLB #1119054 (opens the CSLB license record in a new tab)), bonded and insured, veteran-owned and family-operated design-build company based in Los Angeles. Our own crews design, permit and build pools, backyards, ADUs and interiors across Greater Los Angeles and Orange County.
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