Williamsburg, MA


Williamsburg, MA Accessory Dwelling Unit (ADU) Rules

New Rules allowing Detached ADUs coming in September 2021!!!!


City Acceptance Rating:
N/A

What you need to know: 

Williamsburg does not allow detached accessory dwelling units (ADUs). Granny flats must be constructed within existing space or as an addition.

Type of permit:

A special permit from the zoning board of appeals is required.


ADU rules in Williamsburg:

  • The ADU must have its own kitchen and bath and be within an existing single family dwelling.

  • One of the two units must be owner occupied.

  • The ADU’s floor space must be less than 750 square feet or one-third of the existing living space whichever is greater.

  • No more than three people can live in the ADU

  • Parking must comply with parking requirements outlined in the parking section of the Bylaw.

Other Notes:

  • Human habitation is not allowed in accessory structures, aka backyard homes.

  • Multi-family and two-family homes are allowed in all zoning districts. This means homeowners can convert their homes from single to two family dwelling INSTEAD of adding an ADU.

See the full text here: Zoning Ordinance Section 9.1 Accessory Apartments

Convert/add to eligibleGuest UserFriendliness Score N/A, Williamsburg MA, Western MA