ADU Design in Derby, CT

ADU Design in Connecticut: what governs your project

Connecticut's 2021 zoning reform requires municipalities to allow ADUs as of right, though towns were given a path to opt out of certain provisions. As a result, ADU availability is broad but not uniform across the state.

Energy code

Local zoning and building permits govern size, setbacks, and design. Owner-occupancy requirements and utility connection standards vary by town; septic-system review applies in areas without public sewer.

Permitting & plan check

Connecticut has no county permitting layer — all land use and building permits are handled by its 169 cities and towns. Zoning, wetlands, and building departments each review separately, so pre-application meetings with the town are standard practice for commercial projects.

Good to know

• Connecticut is divided into 169 municipalities, each with its own zoning and wetlands authority, and there is no county permitting layer.
• The Inland Wetlands and Watercourses Act gives local agencies direct regulatory power over work near wetlands and watercourses.
• Long Island Sound's coastline subjects shoreline construction to both state coastal management and tidal wetland rules.

Every discipline, one team