Amherst, MA

Amherst, Massachusetts Accessory Dwelling Unit (ADU) Rules

City Acceptance Rating: 8/10 (10 is most accepting)

What you need to know:

In 2021, Amherst proposed amending its ADU bylaws to increase the maximum square footage of ADUs to 1,000 sq. ft., create a more streamlined permitting pathway and add additional design guidelines. Attached and contained ADUs would be allowed by right; detached ADUs would still require a special permit.

Type of Permit Required:

As accessory uses, accessory dwelling units are exempt from the additional lot area/family requirements of Table 3
ADUs that do not require extensive changes to an exterior of a property are allowed by right in all zoning districts except R-F.
Detached ADUs require a special permit in districts: R-G, R-VC, R-N, R-O, and R-LD Districts

NOTE: Homes that in the Design Review or Town Center Design Review Overlay district are subject to Design review by the Design Review Board. The overlay district can be seen at the end of this post.

ADU Rules in Amherst:

Only one (1) accessory dwelling unit will be permitted as accessory to a one family detached dwelling.
Living area must not exceed 1,000 SF.
They cannot be used as short term rentals (No AirBNB).
One of the units must be owner occupied.
The apartment cannot be occupied by more than 3 adults.
The rental must have a management plan that is submitted to the Building Commissioner for review and approval. (We can help with this.)
If rented, the ADU must be registered and permitted in accordance with the “Residential Rental Property Bylaw”.
Waste must be stored inside until removed from the property. No freestanding dumpsters or trash cans are allowed outside.
A reflective street address sign must be installed for the ADU so it can be easily seen by emergency crews.
Parking must be provided in accordance with Article 7.
Exterior lighting must not shine onto adjacent properties.
The accessory dwelling unit must be designed so that the appearance and scale of the building is compatible with the primary single-family dwelling unit. Detached Accessory Dwelling Units must be clearly accessory to the primary dwelling unit.