Zoning, building permits and septic rules in Ann Arbor, Michigan

Ann Arbor’s own rules

• Building permitRequired

  Commercial buildings in Ann Arbor city that need a certificate of occupancy.

  • Applies to commercial work; residential permit requirements were not verified.
  • Applications go through the STREAM online permitting system.

  “if a permit does not exist, a commercial building permit application will be required for plan review and approval before a certificate of occupancy will be issued.”

• Certificate of occupancyRequired

  Commercial buildings in Ann Arbor city.

  • Requires a finaled commercial building permit on record; if the permit is not finaled it must be reactivated and remaining inspections approved.
  • Residential certificate of occupancy requirements were not verified.

  “a finaled commercial building permit on record with the city of ann arbor is required for a certificate of occupancy to be issued.”

• Local zoningPresent

  Land inside Ann Arbor city limits, under the city's own Unified Development Code (Chapter 55 of Title V).

  • The UDC is amended often; the 12th edition is stated as effective August 23, 2026, including amendments through Ordinance 26-18.

  “the unified development code (chapter 55 of title v of the code of the city of ann arbor) divides the city into zoning districts and contains the development standards for construction in the city”

• Zoning districtsPublished

  Zoning districts inside Ann Arbor city limits.

  • Residential districts include AG, R1A through R1E, R2A, R2B, R3, R4A through R4E and R6 (mobile home park), plus mixed-use and nonresidential districts (Article II, section 5.10 to 5.13).

  “r4a multiple-family dwelling district 19 r4b, r4c, r4d, and r4e multiple-family dwelling districts 19 5.12 r6 mobile home park district 20”

• Minimum lot sizeSpecified

  R1C single-family dwelling district inside Ann Arbor city (main single-family district chosen as representative; R1A, R1B, R1D and R1E are in the same table and were not separately claimed).

  • Lot area is the minimum area per lot for R1C per Table 5.17-1; other use and development standards in the UDC may supersede this table.
  • Table extraction from the PDF was garbled; district-to-column alignment was inferred from the row order, and should be verified against the printed table.

  minimum lot area: >= 7200 sq ft

  “ag 100,000 sq. ft. r1a r1b r1c r1d r1e 20,000 sq. ft. 10,000 sq. ft. 7,200 sq. ft. 5,000 sq. ft. 4,000 sq. ft.”

  One more reviewed finding on this topic

  • Specified — AG agricultural-open space district inside Ann Arbor city.

    “ag 100,000 sq. ft. r1a r1b r1c r1d r1e 20,000 sq. ft. 10,000 sq. ft. 7,200 sq. ft. 5,000 sq. ft. 4,000 sq. ft.”

• SetbacksSpecified

  R1C single-family dwelling district inside Ann Arbor city.

  • Footnote [a]: also see additional regulations in section 5.18.5 (averaging an established front building line).
  • Column alignment inferred from garbled table extraction; verify against the printed Table 5.17-1.

  minimum front required setback: >= 25 ft (footnote [a]: averaging of established front building line (section 5.18.5)) · minimum one side required setback: >= 5 ft · minimum total of two side setbacks: >= 10 ft

  “40 ft. [a] 7 ft. 18 ft. 30 ft. [a] 5 ft. 14 ft. 25 ft. [a] 5 ft. 10 ft. 25 ft. [a] 3 ft. 6 ft. 15 ft. [a] 3 ft. 6 ft.”

• Accessory dwellingsLimited

  Accessory dwelling units on lots in Ann Arbor city with one single-family dwelling as the principal use.

  • ADU floor area up to 600 sq ft on lots less than 7,200 sq ft; up to 800 sq ft on lots of 7,200 sq ft or greater (Table 5.16-2).
  • ADU floor area may not exceed the ground-level floor area of the primary dwelling.
  • ADU is permitted as or within any legally conforming accessory building.
  • Total persons in primary dwelling plus ADU are subject to section 5.16.1 a occupancy limits, with exceptions.

  ADU floor area, lot less than 7,200 sq ft: <= 600 sq ft · ADU floor area, lot 7,200 sq ft or greater: <= 800 sq ft

  “an adu is permitted on a lot that has one single-family dwelling as the principal use. 2. minimum lot area and floor area requirements for accessory dwelling units: table 5.16-2: lot area and floor area requirements for accessory dwelling units lot area adu floor area less than 7,200 sq. ft. up to 600 sq. ft. permitted [a] 7,200 sq. ft. or greater up to 800 sq. ft. permitted [a]”

• Mandatory utility hookupWater (with conditions)

  Buildings for human occupancy in Ann Arbor city abutting a street, alley or right-of-way where a city-owned public water main is available.

  • Connection is required if the public water main is within 200 feet of the property line, or if required by the Washtenaw County health department.
  • Connection must be completed within 90 days after official notice from the city.
  • Annexed property may receive a deferred notice under subsection (2) of the ordinance text.

  distance from property line to public water main: <= 200 ft (or if required by the Washtenaw County health department)

  “provided that the public water main is within 200 feet of the property line, or if required by the washtenaw county health department.”

• Permit processPublished (with conditions)

  Building and certificate of occupancy applications in Ann Arbor city.

  • All applications go through the STREAM online system.
  • Building department at 301 E. Huron St. per search snippet; phone 734-794-6263 per building page.

  “to apply for a certificate of occupancy, please use ann arbor's online permitting system: stream. all paperwork must be applied for through this system.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Ann Arbor or Washtenaw County directly.

• Owner-builder exemption — Owner-builder permitting in Ann Arbor city.
• Inspections — Building inspection requirements in Ann Arbor city.
• Minimum dwelling size — Minimum dwelling floor area in Ann Arbor city.
• Lot coverage — Lot coverage in Ann Arbor city R1C district.
• Building height — Maximum building height in Ann Arbor city R1C district.

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.