Hampton, NH Accessory Dwelling Unit (ADU) Rules

City Acceptance Rating: 8/10

Last Updated: 8.28.2024

What You Need To Know

Applicants proposing an ADU must submit a scaled plan to the Hampton Planning Board showing the ADU, property line distances, and parking spaces. They must also provide scaled exterior elevations and floor plans showing the interior layout of the ADU.

If the proposal involves enlarging a building or increasing the impervious coverage of the lot, and the Building Inspector has concerns about meeting dimensional requirements, the applicant must submit a certified plot plan by a licensed New Hampshire land surveyor with existing and proposed setbacks and impervious coverage calculations. The Building Inspector’s determinations can be appealed to the Zoning Board of Adjustment.

Type of ADU Permit Required

A Conditional Use Permit from the Hampton Planning Board and a Building Permit in accordance with the Hampton Zoning Ordinance is needed.

ADU Rules

An ADU must provide independent living facilities, including sleeping, eating, cooking (stove, refrigerator, sink), and sanitation (shower/tub, toilet, sink).
It can have up to two bedrooms, each between 7x10 feet and 200 square feet.
The owner must occupy either the main dwelling or the ADU as their primary residence.
Each bedroom in the ADU can house no more than two people.
ADUs or the main dwelling cannot be rented for less than six months.
A Certificate of Rental Occupancy is required for rental units.
ADUs cannot be used for business purposes.
ADUs can be used by relatives of the owner without following the rental rules, but a notarized attestation is required.
ADUs must be attached to the main dwelling, with an interior door connecting them.
For buildings with three or more stories, additional egress is required for upper-story ADUs.
Detached ADUs may be permitted under certain conditions, with a maximum footprint of 5% of the lot area.
Enlarging a structure with a detached ADU is prohibited.
ADUs cannot exceed 800 square feet.
ADUs must comply with Wetlands Conservation District regulations.
ADUs must connect to the town sewer or a legal private system, with proper design to prevent freezing.
If using a private well, it must provide sufficient water for both the main dwelling and the ADU.
ADUs must follow the dimensional requirements in Article IV of the Hampton Zoning Ordinance.
ADUs attached to dwellings of three or more stories require sprinkler systems in both units.
ADUs and the main dwelling must remain under the same ownership and cannot be converted to condos.
ADUs are subject to impact fees, equal to the fee for a two-unit structure, with no waivers.

Resources:

www.hamptonnh.gov/DocumentCenter/View/1697/Accessory-Dwelling-Unit-Ordinance?bidId=

Hampton, New Hampshire