Milan, NY ADU Rules: Detached Units Up to 2,000 Sq Ft

By Spenser McCoy

Milan's zoning code draws a sharp line between attached and detached accessory apartments, and the detached option is unusually generous: up to 2,000 square feet, or 75% of your primary dwelling's size, whichever is smaller. That's among the largest detached-ADU allowances we found anywhere in the Hudson Valley. Attached units are more modest — capped at 900 square feet, or 25% of the host building, with a 300 square foot floor either way.

Eligibility is narrower than the size caps suggest: accessory apartments are only permitted in five zoning districts — A5A, A3A, R2A, HA, and HB — so confirming your parcel's district is the first step, not an afterthought. Approval goes through the Zoning Board of Appeals via a special use permit, and Milan takes owner-occupancy seriously: the principal structure has to be owner-occupied at the time of application, with a deed of record at the Dutchess County Clerk's office, and the ZBA can revoke your permit if you stop living there. Selling the property triggers a compliance re-inspection within 60 days, so this isn't a "build it and forget it" approval.

The bottom line: Milan is the move if you want a genuinely large detached unit — a real guest house or income property — and you're planning to stay on the property yourself.

FAQ How big can a detached ADU be in Milan? Up to 2,000 square feet, or 75% of your main house, whichever is less.

Do I have to live on the property? Yes, and it's enforced — the ZBA can revoke your permit if you move out.

Which districts allow accessory apartments? A5A, A3A, R2A, HA, and HB.

Want to confirm your district and size your project right? Book a free Discovery Call with OneBuild.