ADU Rules in Detroit, MI (2026)

Detroit, MI permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Detroit, the Detroit Buildings, Safety Engineering and Environmental Department (BSEED) handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Detroit.

ADU Size Limits

ADU Size Limits in Detroit: Detached ADU: up to 800 sq ft (max height: 24 feet). Attached ADU: 600 sq ft. Detroit ADU regulations are set locally. Detached ADU (carriage house/garage apartment) limited to approximately 800 sqft. JADU is a California-specific concept — not applicable in Michigan. Detroit's vacant land context means many ADUs are built on previously empty lots adjacent to the primary residence.

Permit Fees

ADU Permit Fees in Detroit: Plan check fee: $150-$800. Building permit fee: Based on construction value — typically $800-$3,500. Impact fees: None. School fees: None or N/A. Total estimated permit cost: $1,000-$4,500 total permit fees. Detroit BSEED fee schedule. Detroit does not have impact fees. Detroit Renaissance Zone areas may have some fee exemptions. Source: detroitmi.gov/departments/buildings-safety-engineering-and-environmental-department

Permit Timeline

Detroit ADU Permit Timeline: Detroit Buildings, Safety Engineering and Environmental Department (BSEED): ADU permits typically 6-10 weeks for plan review. Construction 3-8 months depending on contractor availability. Detroit's construction labor market has grown with the city's comeback. Apply through the Detroit Buildings, Safety Engineering and Environmental Department (BSEED) online permit portal. Phone: (313) 224-3158.

Setback Requirements

ADU Setback Requirements in Detroit: Front setback: follows zone standard. Side setback: 3 feet. Rear setback: 4 feet. Detroit rear yard setback for accessory structures is typically 4 ft from the rear property line, 3 ft from the side property line. Detroit's standard lot is approximately 30 ft wide by 100 ft deep in most residential neighborhoods. Per Detroit City Code Chapter 61.

Parking Requirements

Parking Requirements: One parking space required per ADU. Detroit's auto-centric legacy means most parcels have a detached garage or paved pad. New ADU construction in converted garages may require a replacement parking space be created elsewhere on the parcel.

Restrictions & Requirements

• •ADU must comply with Detroit Building Code habitability standards
• •Detached ADU limited to rear yard — not permitted in front or side yards
• •Structure must meet minimum 7 ft ceiling height for habitable space
• •All utilities must be properly connected — no unpermitted electrical or plumbing
• •Historic district overlay (Woodbridge, Indian Village, Boston-Edison) may require additional review
• •Detroit Land Bank Authority properties sold for ADU development subject to DLBA deed restrictions

How Many ADUs Are Allowed?

Number of ADUs Allowed in Detroit: Single-family lots: 1 ADU per lot. Multifamily properties: Accessory units on multifamily parcels subject to site plan review. Detroit's shrinking city context creates unique opportunities: some homeowners purchase adjacent vacant DLBA lots to build a standalone ADU on a newly consolidated parcel. This requires lot consolidation through the City of Detroit.

Historic District Considerations

Frequently Asked Questions