Everything homeowners ask about building an ADU in Detroit — answered with 2026 data.
No — under current zoning Detroit does not allow ADUs. Sec. 50-12-454(a) bars accessory buildings in R1 and R2 from dwelling use and Chapter 50 has no ADU use at all. The 'Let's Build More Housing' amendment (CPC-approved Oct 16, 2025) that would have allowed detached ADUs by right in R2-R6 was never voted on by City Council and its review period expired; as of September 2026 no ADU ordinance is pending. Details: None. Chapter 50 has no accessory dwelling unit use, and Sec. 50-12-454(a) bars accessory buildings in R1 and R2 from dwelling use (pre-1940 carriage houses excepted). The lapsed 2025 'Let's Build More Housing' amendment (CPC-approved Oct 16, 2025; Council never voted and the review period expired) would have allowed one detached ADU by right in R2, R3, R4, R5 and R6 on lots with a single-family, two-family or up-to-three-unit principal dwelling. See our full Detroit ADU rules page for the narrow exceptions and what may change.
ADU construction in Detroit typically costs $90,000-$200,000. The cost per square foot averages $140-$240. Garage conversions are more affordable at $45,000-$100,000, while prefab ADUs cost $75,000-$150,000. Permit fees add BSEED building permit (fee schedule modified 7/18/2025): $2,895.29 at $100,000 project cost plus $27.82 per $1,000 above that (about $4,286 at $150,000); trade permits and a 35% plan-review deposit are extra. Relevant only if the zoning changes. to your budget. See our detailed Detroit ADU cost guide.
Detached ADUs in Detroit can be up to No ADU size rule exists because no ADU use exists. The lapsed proposal. Attached ADUs are limited to Not permitted as an ADU. The lapsed proposal covered only detached units. Junior ADUs (JADUs) have a cap of Not applicable: Michigan has no junior ADU category and Detroit's code has none. Maximum height is Accessory buildings serving a single- or two-family dwelling: one story and 15 ft in all districts, and in R1/R2 no taller than the principal building (Sec. 50-13-209). The lapsed proposal's dimensional tables would have allowed 25 ft for an ADU. You are allowed up to One principal dwelling use per lot as the district's use table allows on a qualifying lot.
Rear setback: Garages and other accessory structures: 3 ft from the rear lot line, or up to the lot line where an alley gives vehicle access (Sec. 50-13-226 encroachment table). The lapsed proposal kept 3 ft and would have waived the rear setback for ADUs on lots that abut an alley (draft Sec. 50-13-212(4)). Side setback: Unattached garages and accessory structures: 3 ft from a side lot line (Sec. 50-13-226); on a corner lot, 10 ft from the side line abutting the street (Sec. 50-13-210). A detached accessory building must sit at least 10 ft from any single- or two-family dwelling (Sec. 50-13-208(3)). The lapsed proposal added 5 ft from a porch or deck and 10 ft from electrical lines unless BSEED waived it. Front setback: Accessory structures may not be located in the required front setback (Sec. 50-13-226); the lapsed proposal likewise barred ADUs from the front yard (draft Sec. 50-13-212(2)). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
No ADU parking rule exists. Household living uses need off-street parking per dwelling unit under Sec. 50-14-34 (Schedule A). The lapsed proposal would have required no added parking for an ADU and reduced the house's requirement by any spaces the ADU displaced (draft Sec. 50-12-466(4)-(5)). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
None in the code (no ADU use exists) and none in the lapsed proposal's text. Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Detroit is typically Not applicable: no ADU permit can be issued under current zoning, and as of September 2026 no ADU ordinance is before City Council. Plan check: Building, structural and zoning plan review is taken as a 35% deposit against the building permit fee, with electrical, mechanical and plumbing plan review at 7% each (BSEED fee schedule Part F); a self-contained unit would need all four. Pre-approved plans availability: None for ADUs. The city's HUD PRO Housing grant funds 'pre-permitted pattern home' plans for infill houses on publicly owned land (2026 Annual Action Plan draft), not backyard units.
Average ADU rental income in Detroit: 1-bedroom units rent for $950-$1,250/month, 2-bedroom units for $1,150-$1,600/month. Short-term rentals: Not applicable: an ADU cannot be built or rented. The lapsed proposal would have barred ADU stays of 27 or fewer consecutive days (draft Sec. 50-12-466(1)g). Expected ROI: Not calculable: no ADU can be permitted. A legally occupied pre-1940 carriage house is the only rentable rear unit in R1/R2.
The minimum lot size for an ADU in Detroit is Not applicable today. The lapsed proposal would have allowed an ADU on a zoning lot of any area or width (draft Sec. 50-12-466(3)); the district tables' minimum lot area and width still govern any new principal dwelling. This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Detroit, a garage conversion typically costs $45,000-$100,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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