Detroit Permit Guide · 2026

ADU / Garage Conversion Permits
in Detroit, MI

Permit fees for a ADU or garage conversion in Detroit typically run $825–$3,325. Here's exactly which permits you need, what they cost, and how long MI review takes.

Do you need a permit for a ADU or garage conversion in Detroit?

Always — converting space into a dwelling unit triggers full plan review, zoning approval, and utility sign-offs in Detroit. Permit fees for a typical $166,793 ADU or garage conversion run about $825–$3,325 (valuation-based fee plus plan review), and MI plan review typically takes 2–4 weeks.

Permits you'll likely need

Building

full plan review for the dwelling conversion

Zoning / occupancy

ADU ordinance compliance and occupancy approval

Utilities

sewer, water, and electrical service connections

Fire / egress

separate egress and smoke/CO requirements

Usually exempt

Nothing meaningful — every part of a ADU or garage conversion runs through permitting. Budget for it up front.

MI permit note

Detroit & Urban Home Challenges: Detroit and other cities have older homes with deferred maintenance Older Detroit homes often have outdated electrical, lead paint, and foundation issues. Reddit users recommend comprehensive inspections. The city has permit requirements but enforcement varies by neighborhood.

How to get ADU or garage conversion permits in Detroit

1
Confirm what triggers a permit
Building, Zoning / occupancy, Utilities, Fire / egress permits apply when the scope includes full plan review for the dwelling conversion. Cosmetic-only scopes may be exempt.
2
Budget the fee
Plan for $825–$3,325 in Detroit — a valuation-based fee on a typical $166,793 project plus plan review.
3
Apply with complete documents
Submit scope, drawings, and contractor license info to the Detroit building department. MI plan review typically takes 2–4 weeks.
4
Verify it in the bid
A complete Detroit bid lists permit fees as a line item. If a bid omits permits — or suggests skipping them — analyze it before signing.

ADU / Garage Conversion permits in Detroit: FAQ

Do I need a permit for a ADU or garage conversion in Detroit?

Always — converting space into a dwelling unit triggers full plan review, zoning approval, and utility sign-offs in Detroit, MI. When in doubt, call the Detroit building department before work starts — unpermitted work can block a future sale.

How much do ADU or garage conversion permits cost in Detroit?

Expect roughly $825–$3,325 in Detroit for a typical $166,793 ADU or garage conversion. Most jurisdictions charge a valuation-based fee of about 0.5–2% of project value, plus plan review and per-trade permit minimums.

How long does a ADU or garage conversion permit take in Detroit?

Simple trade permits are often issued over the counter in Detroit. Where plan review applies, MI turnaround typically runs 2–4 weeks. Submit complete drawings the first time — resubmittals are the most common cause of delay.

Who pulls the permit — me or my contractor?

Usually your contractor pulls permits for a ADU or garage conversion, and their license is attached to the work. A contractor who asks you to pull an owner's permit for contractor-performed work is shifting liability onto you — treat that as a red flag when reviewing bids.

More Detroit permit guides

ADU / Garage Conversion permits in other MI metros

Is your ADU or garage conversion bid fair?

A typical Detroit ADU or garage conversion runs $166,793. Check your contractor's bid — permits included — against live 2026 local data, free.

Detroit ADU or garage conversion costs AUDIT MY BID

Data sources: Zonda Cost vs Value 2025; Houzz 2024 Cost Guides; BLS OEWS 2023; FRED regional price indices; Reddit homeowner & contractor reports.

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ADU / Garage Conversion Permits in Detroit, MI