Detroit does not allow accessory dwelling units under its current zoning code: Sec. 50-12-454(a) of Chapter 50 bars accessory buildings in the R1 and R2 districts from being occupied for dwelling purposes (carriage houses built before 1940 excepted), and no 'accessory dwelling unit' use exists anywhere in the ordinance. The 'Let's Build More Housing' text amendment, approved by the City Planning Commission on October 16, 2025, would have added Sec. 50-12-466 (one detached ADU by right in R2-R6, up to the smaller of 1,200 sq ft or 60% of the main house, 25 ft tall, no lot minimum, no added parking), but City Council never voted on it and the City Planning Commission reports that the review period expired. As of September 2026 no ADU ordinance is before Council; the city's HUD PRO Housing-funded zoning code update is the likely next vehicle. Check with the City Planning Commission (313-224-6376) before spending anything on plans.
Zoning & Size Requirements [1][2][3][4][5][6]
No — Detroit does not allow ADUs under current zoning. 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.
| Allowed Zones | 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. |
| Max Size (Detached) | No ADU size rule exists because no ADU use exists. The lapsed proposal (draft Sec. 50-12-466(1)e) would have capped an ADU at the smaller of 1,200 sq ft or 60% of the principal dwelling's gross floor area. Today a building accessory to a one- or two-family house is limited to one story and 15 ft (Sec. 50-13-209). |
| Max Size (Attached) | Not permitted as an ADU. The lapsed proposal covered only detached units (freestanding or combined with a garage). A basement or attic apartment inside the house is a second dwelling unit, possible only where the district's use table (Sec. 50-12-22) allows a two-family dwelling on that lot and the lot meets the district's own standards; confirm with BSEED zoning staff. |
| Max Size (JADU) | Not applicable: Michigan has no junior ADU category and Detroit's code has none. |
| Max Height | 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. |
| Max Units | One principal dwelling use per lot as the district's use table allows (Sec. 50-12-22); no accessory unit. The lapsed proposal capped ADUs at one per zoning lot (draft Sec. 50-12-466(1)b). |
Setback Requirements [1][2][3][4][5][6]
Because Detroit does not permit ADUs, there are no ADU-specific setback or parking standards; the accessory-structure rules below are what a future unit would start from. Owner-occupancy is set by local rules (confirm with the city).
| 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)). |
| Parking Required | 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)). |
| Owner Occupancy | None in the code (no ADU use exists) and none in the lapsed proposal's text. |
| Min Lot Size | 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. |
Permit Process & Fees [7][8]
Detroit cannot issue an ADU permit under current zoning. The fees and timelines below are the general building-permit terms that would apply if the rules change.
| Approval Process | No ADU permit path exists because the use is not allowed: BSEED cannot issue a building permit for a dwelling unit in an accessory building in R1 or R2 (Sec. 50-12-454(a)), and no special-approval route for one is published. Ask BSEED Zoning for a zoning verification letter ($93 per address) if you are told otherwise, and watch the City Planning Commission's ordinance page for any revived text. |
| Review Timeline | Not applicable: no ADU permit can be issued under current zoning, and as of September 2026 no ADU ordinance is before City Council. |
| Permit Fees | 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. |
| Impact Fees | None: the BSEED fee schedule lists no development impact or capacity fee. Budget instead for DWSD water and sewer connection charges if a separate service is ever needed. |
| 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 | 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. |
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Construction Costs [9][10]
If ADUs become legal in Detroit, building one would run roughly $90,000-$200,000 ($140-$240 per sq ft) at today's regional rates; a garage conversion about $45,000-$100,000.
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| Average Build Cost | $90,000-$200,000 |
| Cost per Sq Ft | $140-$240 |
| Garage Conversion | $45,000-$100,000 |
| Prefab ADU (Installed) | $75,000-$150,000 |
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Rental Income Potential [11][12]
A 2-bedroom unit in Detroit would rent for around $1,150-$1,600/mo at current market rates — a hypothetical figure while ADUs are not permitted.
| Avg Rent (1 Bedroom) | $950-$1,250/mo |
| Avg Rent (2 Bedroom) | $1,150-$1,600/mo |
| Short-Term Rental | 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). |
| Est. Annual ROI | Not calculable: no ADU can be permitted. A legally occupied pre-1940 carriage house is the only rentable rear unit in R1/R2. |
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Recent Law Changes
What's Changed Recently
- September 20, 2026: the City Planning Commission's ordinance page states City Council did not vote on the 'Let's Build More Housing' (Housing and Parking) amendment and the review period expired; no ADU ordinance is before Council, so this page's status changed from 'pending' to 'prohibited'.
- October 16, 2025: CPC approved the revised text amendment (draft Sec. 50-12-466: one detached ADU by right in R2-R6, the smaller of 1,200 sq ft or 60% of the house, 25 ft, no lot minimum, no added parking, no stays of 27 days or fewer). It was never adopted.
- December 2025: Council adopted the separate Adaptive Reuse (effective Dec 23, 2025) and Screening and Fencing text amendments; neither touches ADUs. The Sixth General Text Amendment (lofts, definitions) was still in the Planning and Economic Development committee's unfinished business on Sept 10, 2026 and has no ADU provision.
- 2026: the city's $4.2 million HUD PRO Housing grant funds a zoning code update and a pre-permitted pattern-home program (2026 Annual Action Plan draft, June 2026); no revived ADU text has been published.
Tips for Building an ADU in Detroit
- Do not buy plans or start site work: Sec. 50-12-454(a) bars accessory buildings in R1 and R2 from dwelling use, and the by-right ADU proposal lapsed without a Council vote.
- A carriage house built before 1940 that has been continuously occupied may keep its dwelling use in R1/R2 (Sec. 50-12-454(a)); get a BSEED zoning verification letter ($93 per address) before buying a property on that basis.
- In R2-R6 a second unit is only possible as a two-family or multi-family principal use that meets the district's full lot-area, width and setback standards (Sec. 50-13-3 to 50-13-7); ask BSEED Zoning whether your lot qualifies before designing anything.
- Any revived ADU text must clear a City Planning Commission public hearing, a Council Planning and Economic Development committee hearing and a formal-session vote before it is law; the CPC's 'Ordinances' page and the committee agendas are the places to watch.
- Cost basis: the ranges are HomeGuide/Angi national guides (accessed July 2026, not Detroit-specific) and are hypothetical until ADUs are legal; Michigan frost-depth footings and Detroit's aging sewer laterals push real quotes above any prefab sticker price.
ADU Builders in Detroit
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Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- City Planning Commission — Ordinances: DRAFT Housing and Parking Ordinance ('Let's Build More Housing'), status note 'City Council did not vote on this ordinance and the review period expired' city_website — Accessed 2026-09-20
- Let's Build More Housing Text Amendment — Approved as Revised 10-16-25 (signed): draft Secs. 50-12-454, 50-12-466, 50-13-3, 50-13-208 to 50-13-212, 50-13-226 city_website — Accessed 2026-09-20
- Zoning Ordinance to Build More Housing — City of Detroit (Mayor's Office project page) city_website — Accessed 2026-09-20
- Planning and Economic Development Standing Committee agenda, September 10, 2026 (read via the Wayback Machine capture of Sept 17, 2026) city_website — Accessed 2026-09-20
- Detroit council punts zoning changes — BridgeDetroit, Nov 17, 2025 news_media — Accessed 2026-09-20
- Detroit zoning proposals: What they are and what to know — Outlier Media news_media — Accessed 2026-09-20
- BSEED Fee Schedule, effective January 1, 2024, modified July 18, 2025 (Building and Residential Permits; Part F Plan Review; Zoning Fees) city_website — Accessed 2026-09-20
- City of Detroit 2026 Annual Action Plan (Draft), June 2026 — PRO Housing grant: zoning code update and pre-permitted pattern home program city_website — Accessed 2026-09-20
- How Much Does It Cost to Build an ADU? — HomeGuide (national guide) industry — Accessed 2026-07-10
- How Much Does an ADU Cost to Build? — Angi (national guide) industry — Accessed 2026-07-10
- Average Rent in Detroit, MI — RentCafe (data as of Aug 31, 2026) industry — Accessed 2026-09-20
- Detroit, MI Rent Research — Zumper (updated Sept 19, 2026) industry — Accessed 2026-09-20
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