What is an ADU?
As described by the Executive Office of Housing and Livable Communities:
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 policy recently signed by the governor allows property owners to build an ADU without having to get special or discretionary approval from the local zoning board.
ADUs can be internal within an existing primary residence, like converting a basement into an apartment, attached to a primary residence as a new construction addition, or completely detached, like a cottage or converted detached garage in a backyard.
The Affordable Homes Act amends the definition of accessory dwelling unit under Section 1A of Chapter 40A of the General Laws to clarify that the maximum size of an ADU is no more than half of the gross floor area of the principal dwelling, or 900 square feet, whichever is smaller. The definition was also amended to prohibit owner-occupancy requirements and unreasonably restricting the creation or rental of an ADU.