Manchester, New Hampshire

Manchester, NH Accessory Dwelling Unit (ADU) Rules

City Acceptance Rating: 8/10

Last Updated: 8.28.2024

What You Need To Know

Only one ADU is allowed per single-family home, which can be within, attached to, or above the garage, or as a standalone structure. The owner must live in either the main dwelling or the ADU, and both must remain under common ownership. ADUs cannot exceed 900 square feet. The design must match the main house, and new ADUs require a conditional use permit and impact fees.

Type of ADU Permit Required

Conditional Use Permit required.

ADU Rules

  • Quantity: Only one ADU is allowed per single-family home. It can be within, attached to, or above the garage, or as a standalone structure. Garage ADUs must not reduce required parking space.

  • Owner Occupied: The owner must live in either the main dwelling or the ADU. Both units must stay under common ownership and cannot be separately sold. A deed restriction requiring owner occupancy must be recorded before occupancy.

  • Size: ADUs cannot exceed 900 square feet or the height of the main structure and are limited to two bedrooms.

  • Location: ADUs are not allowed in front yards and must be at least 10 feet from side and rear property lines, with detached ADUs at least 5 feet from the main structure.

  • Parking: One additional off-street parking space is required for the ADU.

  • Utilities: Septic systems must meet NH standards for the total occupancy. ADUs must connect to existing utilities if available.

  • Design and Construction: New entrances for ADUs cannot face the street. The design must match the main residence.

  • Internal Construction: ADUs within existing structures do not require a conditional use permit, even with minor exterior changes.

  • External Construction: New construction for ADUs requires a conditional use permit and must match the main home's exterior design.

  • Impact Fees: New ADUs require the payment of impact fees as per Article 13.

Resources:

https://www.manchesternh.gov/Portals/2/Departments/pcd/Forms/AccessoryDwellingUnits-Information.pdf

Attached ADU, Convert Existing Space, Detatched ADUDeanna DuffeyNew Hampshiure, Friendliness Rating 8/10, Manchester