In Michigan, most adu projects cost between $50,000 and $200,000 per job, with a typical price near $100,000. Local labour, permits and materials move the final price, so treat the range below as a planning guide.
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
At a glance
- Typical range$50,000 – $200,000
- Unitper job
- Cities covered33
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.
By city in Michigan
- Ann Arbor
- Battle Creek
- Bay City
- Dearborn
- Dearborn Heights
- Detroit
- East Lansing
- Farmington Hills
- Flint
- Grand Rapids
- Holland
- Kalamazoo
- Kentwood
- Lansing
- Lincoln Park
- Livonia
- Muskegon
- Novi
- Pontiac
- Port Huron
- Portage
- Rochester Hills
- Royal Oak
- Saginaw
- South Lyon
- Southfield
- St. Clair Shores
- Sterling Heights
- Taylor
- Troy
- Warren
- Westland
- Wyoming
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.