ADU Rules in Vergennes, Vermont

Vergennes holds a singular distinction: it is the smallest city in Vermont and one of the smallest cities in the United States, with a population of approximately 2,500 residents. Despite its tiny footprint — just about 1.5 square miles — Vergennes has city status (incorporated as a city in 1788, making it one of the oldest chartered cities in New England). Located in Addison County along Otter Creek, with access to Lake Champlain just a few miles to the west, Vergennes combines a historic downtown with a compact residential neighborhood fabric.

Vermont Act 47 (2023) — ADU Rights Statewide

Vermont Act 47 (2023) requires all Vermont municipalities — including the City of Vergennes — to allow at least one ADU by right on any residential lot containing a single-family or two-family dwelling. For Vergennes property owners:

• ADUs must be approved without requiring a public hearing, variance, or discretionary conditional use review, provided objective dimensional standards are met
• The city may maintain its own dimensional standards (setbacks, maximum size, height) but may not use subjective design criteria to effectively block ADUs
• Both attached and detached ADUs are covered

Act 47 is particularly impactful in a compact historic city like Vergennes, where older homes on smaller lots frequently have potential for in-law suites, carriage house conversions, or detached backyard units.

ADU Types Permitted

• Attached ADUs — in-law suites, basement apartments, or upper-floor secondary units within the primary structure
• Detached ADUs — freestanding backyard cottages, carriage house or barn conversions
• Garage conversions — converting existing attached or detached garages into habitable units
• Interior ADUs — second units created within the existing floor plan of the principal home

Vergennes's historic residential fabric includes many older homes with detached carriage barns or garages that may be suitable for conversion, subject to applicable standards.

Size, Setbacks, and Historic Character

Vergennes's zoning regulations set local dimensional standards. In a compact historic city, lots tend to be smaller than in rural Vermont towns, and setback requirements may reflect this urban character:

• Maximum ADU floor area (verify current local standard — Act 47 may have prompted updates)
• Rear and side yard setbacks for detached ADUs
• Height limits consistent with the accessory structure standards of the applicable zoning district
• Any historic district or design review requirements that apply to exterior alterations on historically significant properties

Contact the Vergennes Planning and Zoning office for current standards, particularly if your property is within any locally designated historic area.

Otter Creek and Lake Champlain — Flood and Environmental Considerations

Otter Creek flows through the eastern portion of the city and is subject to:

• FEMA Special Flood Hazard Areas (SFHAs): ADUs in SFHAs must be elevated to or above the Base Flood Elevation and require a floodplain development permit.
• Vermont ANR Fluvial Erosion Hazard (FEH) Zones: Properties within river corridor FEH zones may face setback requirements of 50+ feet from the Otter Creek channel.

Lake Champlain Shoreland: Properties near Lake Champlain are subject to Vermont's Shoreland Protection Act (Act 110 of 2014, 10 V.S.A. § 1441 et seq.), which regulates development within 250 feet of mean water level. If your property falls within this shoreland buffer, additional state review may be required for ADU construction.

Check both the FEMA Flood Map Service Center at msc.fema.gov and the Vermont ANR Natural Resources Atlas at anrmaps.vermont.gov.

Act 250 — Vermont Statewide Land Use

A single residential ADU addition in Vergennes does not typically trigger Act 250 review. Act 250 jurisdiction applies to larger developments, subdivisions of 10 or more lots, or construction on land above 2,500 feet elevation — none of which apply to a typical ADU project in this flat lakeside city.

Permit Process

1. Confirm the parcel's flood zone and FEH zone status (and shoreland zone if applicable) using Vermont ANR and FEMA maps
2. Contact the Vergennes Planning and Zoning office for current dimensional standards and any historic district requirements
3. Submit a zoning permit application with site plan and floor plans
4. Obtain a building permit under Vermont Fire & Building Safety Division requirements
5. Pass all required inspections and receive a certificate of occupancy

Contact Information

City of Vergennes Planning and Zoning

• Address: 120 Main Street, Vergennes, VT 05491
• Phone: (802) 877-2287
• Website: vergennescity.org

Disclaimer: Zoning regulations and state law change frequently. This page is provided for general informational purposes only. Always verify current ADU requirements with the City of Vergennes Planning and Zoning office and consult a licensed Vermont architect or contractor before beginning any project.