Most adu projects cost between $50,000 and $200,000 per job, with a typical price near $100,000. Prices vary by state and city, so the range below is a planning guide rather than a quote.
Typical adu cost
$50,000 – $200,000
per job · typical $100,000
A general planning range, not a quotation.
Adu cost breakdown
- Garage conversion$30,000 – $80,000typical $50,000
- Attached ADU (addition)$80,000 – $200,000typical $120,000
- Detached ADU (new build)$100,000 – $300,000typical $180,000
What ADUs costs
Costs cover design, permits, construction, and utilities for adding a separate living unit on your property. Detached units are pricier than attached or garage conversions. Local regulations and site conditions significantly affect price.
Costs by state
- Alabama
- Alaska
- Alberta
- Arizona
- Arkansas
- British Columbia
- California
- Colorado
- Connecticut
- Delaware
- District of Columbia
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Manitoba
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Brunswick
- New Hampshire
- New Jersey
- New Mexico
- New York
- Newfoundland and Labrador
- North Carolina
- North Dakota
- Northwest Territories
- Nova Scotia
- Nunavut
- Ohio
- Oklahoma
- Ontario
- Oregon
- Pennsylvania
- Prince Edward Island
- Quebec
- Rhode Island
- Saskatchewan
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
- Yukon
Frequently asked questions
How much does an ADU cost on average?
Nationally, $100,000–$200,000 for a typical 600-1,200 sq ft unit. Garage conversions may cost less, while high-end detached units exceed $250,000.
What drives ADU costs?
Size, type (attached/detached), foundation, plumbing/electrical runs, and local permit fees. Site conditions like sloping land or need for a new sewer line increase costs.
How can I save on ADU construction?
Use prefabricated units, convert existing space, shop for contractors, and finance with a HELOC or construction loan. Check for local grants or incentives for ADUs.