Do I Need a Permit to Build an ADU in Detroit, MI?

ADU-specific overview

What makes this different from a simple accessory structure

Pulled from the city's ADU guidance and linked code references.

Permit type: Residential building permit through the Detroit Buildings, Safety Engineering and Environmental Department (BSEED), submitted via the ePLANS system. Both new detached ADUs and attached ADUs (additions or garage conversions) require a full building permit under the Michigan Residential Code. Zoning review for Chapter 61 compliance is part of the ePLANS submission.
Maximum size: 600 square feet of floor area, and the ADU cannot exceed the floor area of the principal dwelling. Detroit's Chapter 61 imposes this size cap on all ADUs in R1 and R2 districts. Footprint must also comply with the applicable setback, lot coverage, and yard requirements.
Setbacks: The ADU must comply with the setback standards of the applicable residential district under Detroit's Zoning Ordinance. Detached ADUs are typically located in the rear yard and must maintain minimum setbacks from all lot lines and from the principal structure as specified in Chapter 61. Confirm the specific setback requirements for your district and parcel through BSEED or the zoning ordinance.
Owner occupancy: Required. Detroit's ADU ordinance requires the property owner to reside in either the principal dwelling or the ADU as their primary residence. Michigan does not have a statewide law prohibiting local owner-occupancy requirements for ADUs, so this condition is legally enforceable in Detroit.
Parking: Detroit's ADU standards do not expressly waive parking requirements. The underlying zoning district's parking requirements still apply to the lot. Confirm whether the ADU design affects existing or required off-street parking on the parcel with BSEED before finalizing the site plan.
Utilities: Utility connections for water, sewer, gas, and electrical must be reviewed as part of the BSEED permit process. Depending on the ADU layout, a separate service lateral or meter may be required. The Detroit Water and Sewerage Department and DTE Energy have their own review and connection processes that should be coordinated in parallel with the BSEED permit.
JADU distinction: Michigan and Detroit do not use a California-style Junior ADU (JADU) designation. Interior conversions of existing space within the principal dwelling are treated as attached ADUs and follow the same Chapter 61 and Michigan Residential Code permit path. Garage conversions are a common ADU approach in Detroit and follow the same permitting process.

Michigan does not have a statewide ADU preemption law comparable to California SB 897, Washington HB 1337, Oregon HB 2001, or Colorado HB24-1152. Detroit's ADU rules are governed by local zoning ordinance Chapter 61, which means the owner-occupancy requirement, size cap, and eligible districts are local provisions enforceable under Michigan law — not preempted by state mandate.
Detroit's ADU program is focused on R1 and R2 single-family and two-family districts. Property owners outside these districts, or with lots that do not have a single-family principal structure, should confirm ADU eligibility with BSEED before beginning design, as the by-right allowance under Chapter 61 may not apply.
Garage conversions are a practical ADU path in many Detroit neighborhoods given the prevalence of detached garages. The conversion must still comply with all Chapter 61 standards — size cap, owner-occupancy, setbacks — and requires a full building permit through BSEED ePLANS including structural review, utility work, and inspections.

Fees

Estimated city fees

Baseline for a simple permitted adu: $600–$2,400+ estimated combined BSEED permit and plan review fees for a typical Detroit ADU; trade permits and any BZA variance costs are additional

Fee	Amount	Notes
Building permit fee (valuation-based)	$500–$2,000+ (estimated range)	Detroit BSEED residential building permit fees for ADU construction are based on declared project valuation. A new detached ADU typically generates materially higher fees than a simple accessory structure permit. Verify current fee schedules through the BSEED ePLANS portal at detroitmi.gov/bseed.
Plan review fee	$100–$400 (estimated)	A plan review fee is assessed for review of ADU construction drawings. Combined permit and plan review for a typical Detroit ADU commonly runs $600–$2,400 depending on scope and valuation.
Michigan state building surcharge	$10–$30	Michigan assesses a state building surcharge on permitted residential construction, collected by BSEED at permit issuance and remitted to the State of Michigan.
Trade permits (electrical, plumbing, mechanical)	$200–$1,000+ each depending on scope	Habitable ADUs with full utility service require separate electrical, plumbing, and mechanical permits through BSEED, each with associated review fees.
Zoning variance (if required)	Varies; hearings add meaningful time and cost	ADUs that comply with Chapter 61 dimensional standards in R1/R2 districts do not require a variance. If the design exceeds dimensional limits or the zoning district does not permit ADUs by-right, a variance from the Detroit Board of Zoning Appeals (BZA) may be required before BSEED can issue a permit.

Documents

Required documents

Building permit application submitted through the Detroit BSEED ePLANS system at detroitmi.gov/bseed. Detroit does not accept paper applications for new residential ADU permits.
Zoning compliance documentation confirming the ADU is permitted in the applicable district and meets Chapter 61 dimensional standards: maximum 600 sq ft floor area, required setbacks, lot coverage, and yard requirements.
Scaled site plan showing lot lines, the principal dwelling, the proposed ADU footprint, setback dimensions from all lot lines, driveway/access points, and any existing accessory structures.
Construction drawings including floor plans, elevations, cross sections, and roof plan for the ADU, designed to comply with the Michigan Residential Code (MRC).
Structural footing and framing details showing footing depth below the 42-inch Detroit frost line, post/beam/joist sizing, and all connection hardware.
Utility plans showing proposed water, sewer, gas, and electrical service connections for the ADU, including meter locations and any new service entry points.
Owner-occupancy documentation or affidavit confirming the property owner resides or will reside in the principal dwelling or the ADU as their primary residence, as required by Detroit's ADU ordinance.
Licensed contractor information including Michigan contractor license number, or owner-builder documentation if applicable under state law.

Timeline

Typical timing

Plan review: 10–25 business days for standard residential plan review through BSEED ePLANS
Total cycle: 4–9 months from initial design to final inspection for a typical Detroit ADU

Detroit BSEED review timelines can vary with application volume. BZA variance proceedings, if required, add 2–4 months before the permit application can be accepted. Utility coordination with Detroit Water and Sewerage Department and DTE can also add time if new service connections are needed.

Process

How the permit process works

Confirm ADU eligibility under Detroit Zoning Ordinance Chapter 61 Verify that your parcel is in an R1 or R2 district and that the principal structure is a single-family dwelling. Chapter 61 limits ADUs to these districts as an accessory use to single-family homes. Use the Detroit Open Data portal or BSEED's parcel search to confirm zoning.
Verify owner-occupancy compliance and design constraints Detroit's ADU ordinance requires the property owner to occupy either the principal dwelling or the ADU. Confirm this requirement applies to your situation before investing in full permit drawings. Also verify the 600 sq ft maximum size cap, required setbacks, and lot coverage limits for your parcel.
Design the ADU to MRC standards including frost line and snow load Michigan's cold climate means all footings must extend below the 42-inch frost line in Detroit. Snow load design and adequate insulation to meet the Michigan Energy Code are also required. Engage a contractor or design professional familiar with BSEED submissions and Michigan Residential Code requirements.
Plan utility connections and service strategy Confirm water, sewer, gas, and electrical service strategy before finalizing the permit application. Depending on the ADU configuration, a separate service lateral or meter may be required. The Detroit Water and Sewerage Department and DTE Energy may have their own review processes for new connections.
Submit the permit application through BSEED ePLANS Submit the building permit application through the BSEED ePLANS system at detroitmi.gov/bseed with all required documents: site plan, construction drawings, structural details, utility plans, owner-occupancy documentation, and contractor license information. Detroit does not accept paper submissions for new residential building permits.
Respond to zoning and plan review comments BSEED zoning and plan reviewers will check the submission for compliance with Chapter 61 dimensional standards and the Michigan Residential Code. Address any correction notices and resubmit through ePLANS. Track review status through the portal.
Pay fees, obtain trade permits, and begin construction Once plan review approvals are issued, pay the building permit fee, plan review fee, and Michigan state surcharge through ePLANS. Pull separate trade permits for electrical, plumbing, and mechanical work. Post the building permit card on site before starting construction. Keep approved drawings on site throughout.
Schedule BSEED inspections and close the permit Schedule required BSEED inspections: footing (before concrete pour, to verify frost-line depth), framing, rough-in utilities, and final inspection. After all inspections pass, BSEED closes the permit. The ADU may not be lawfully occupied before the final inspection is passed and the permit is closed.

Code basis

What Detroit reviews against

Detroit Zoning Ordinance Chapter 61 (City of Detroit Zoning Ordinance, as amended) for land-use allowances, ADU standards, and dimensional requirements; Michigan Residential Code (MRC, most recent edition adopted by Michigan), based on the International Residential Code (IRC) with Michigan amendments, enforced by the Detroit Buildings, Safety Engineering and Environmental Department (BSEED).

Residential permit page Detroit permit portal

If you skip the permit

What can go wrong

Detroit BSEED can issue a stop-work order requiring all construction to cease immediately and post a violation notice on the property.
BSEED can require removal or correction of unpermitted ADU work at the owner's expense; after-the-fact permitting for an ADU may require opening concealed construction for inspection.
Michigan law requires sellers to disclose known code violations and unpermitted construction — an unpermitted ADU creates material disclosure obligations that can affect sale price or require remediation before closing.
A non-permitted ADU cannot lawfully be occupied or rented; it lacks a final BSEED inspection and closed permit.
Improper utility connections create both safety risk and expensive corrections; separate utility permits are required for habitable ADUs.
Lenders and title companies increasingly flag unpermitted residential structures, creating complications at refinancing, home equity applications, and property sale.