Accessory Dwelling Units - ADUs

In August, 2024 the state governor signed the Affordable Homes Act into law. It includes an amendment to the Zoning Act to allow, across Massachusetts, ADUs up to 900 SF or half the size of the principal dwelling (whichever is smaller) by right, in zoning districts where single-family homes are permitted. The law also prevents towns from requiring owner-occupancy of either the ADU or the principal dwelling. Also, regulations produced by EOHLC interpret several aspects in ways that differ from Westford’s 2022 bylaw and are designed to allow ADUs more expansively. At Special Town Meeting 2025, the town voted to amend the ADU bylaw to be compliant with the updated state law (final bylaw to be published soon). The state regulations were published on January 31, 2025, and the new law came into effect on February 2, 2025. Further information is available on the state website.

What is an ADU?

An accessory dwelling unit is a small residential living space located on the same lot as another home. ADUs can play a significant role in our housing crisis. The ADU law allows property owners to build an ADU by right.

ADUs can be inside an existing home, like converting a basement into an apartment, attached to a primary residence as an addition, or completely detached, like a cottage or converted garage in a backyard.

Shows different styles of ADUs

Helpful Links and Documents

  1. ADUs Slideshow
  2. ADU Discussion Request Form 2026