ADU Laws in Michigan — 2026 Guide

Yes, conditionally — Michigan permits ADUs on qualifying lots per HB 4633 (2024). Larger cities generally lead adoption; smaller municipalities may apply variance or conditional-use permit requirements.

Michigan permits ADUs up to approximately 900 square feet per HB 4633 (2024). Individual municipalities may set lower caps; verify with your city or county planning department before ordering.

Yes — every ADU in Michigan requires a building permit issued by the city or county. The permit process typically runs 35-100 days depending on jurisdiction, complexity, and whether discretionary review is triggered.

Long-term rental is generally permitted in Michigan where the ADU itself is legal. Short-term rental (under 30 days) is subject to municipal registration and may require additional permits; check with your local planning department.

No — Michigan does not require owner-occupancy under state statute per HB 4633 (2024). Local ordinances may still add owner-occupancy requirements in specific cities.

Most Michigan municipalities permit ADUs in single-family residential zones (R-1, R-2 equivalent). Michigan HB 4633 (2024) required cities over 50,000 population to permit at least one ADU pathway by right. Grand Rapids permits by-right in most residential zones. Consult your city zoning code for the specific district table.

Typical ADU permit timelines in Michigan run 35-100 days from application to approval. Fast-permitting counties can move in under 30 days; metro-core jurisdictions with discretionary review can extend to 150+ days.

Yes — most Michigan municipalities apply the same setback requirements to ADUs that apply to the primary structure (typically 5-10 feet rear and side, 15-25 feet front). Some cities apply reduced setbacks specifically for detached ADUs. Verify with your city zoning code.

Yes — several financing pathways cover ADU purchases in Michigan: Fannie Mae HomeStyle Renovation, FHA 203(k), construction-to-perm loans, HELOC on the primary residence, and cash. Check with modular-friendly lenders like 21st Mortgage, Cascade Financial, and Triad Financial for the Michigan-specific product.

The JADU (Junior ADU) category originated in California and is not a distinct legal category in Michigan. Most Michigan municipalities regulate internal conversions and detached units under a single ADU/accessory apartment definition.