Northampton, MA

Northampton, Massachusetts’ Accessory Dwelling Unit (ADU) Rules

City Acceptance Rating: 9/10 (10 is most accepting)

What you need to know: 

In 2014, Northampton joined many cities in MA by revising its zoning bylaw to make it easier for homeowners to build accessory apartments in all zoning districts. They have attractive rules in their zoning ordinance and biggest restrictions are related to environmental protections.

Type of permit required:

Attached ADU:s

Attached ADUs are allows by right in all residential zoning districts.

For detached ADUs:

By Right with administrative site plan review:

• Rural Residential

• Suburban Residential

Allowed in By Special Permit:

• All other residential zoning districts including Farms, Forests, Rivers (FFR), and Water Shed Protection (WSP).

ADU Rules in Northampton:

• The living area cannot be greater than 900 SF.

• New entrances must be on the side or rear of the building.

• An ADU can only be added to a single-family home (2-family properties don’t qualify).

• There can only be 1 ADU per lot.

• No more than 3 people can live in the ADU.

• Detached ADUs must abide by the primary home’s setback requirements (different per zone).

• New exterior entrances must be located on the side or back of the building.

• The owner must live in one of the two dwelling units.

• The ADU must function as a fully separate unit with separate kitchen, bath, and egress.

• The lot must have at least 3 parking places.

See the full text here: Zoning Ordinance Section 350-10.10, Accessory Apartments