The Three Massachusetts ADU Bills

Accessory Dwelling Units (ADUs) have been identified as a crucial element in addressing housing shortages and promoting affordable living options in Massachusetts. Three legislative bills—S2834 from the State Senate, H4707 from the State House of Representatives, and H4138 from the Governor’s office—propose remarkably similar frameworks to encourage the development of ADUs. This post examines how ADUs are defined in these documents, what local zoning restrictions are, and are not, allowed under the proposed laws, and the intended effect of the three bills.

Defining Accessory Dwelling Units

In each of the legislative documents, ADUs are defined as a self-contained housing unit including sleeping, cooking, and sanitary facilities located on the same lot as a principal dwelling.  The ADU must maintain a separate entrance, either from the outside or through a shared entry with the principal dwelling, and can be no larger than half the size of the principal dwelling, or 900 square feet, whichever is smaller​​​​​​.

Limiting Restrictions on Development

The proposed laws place clear limitations on the types of restrictions municipalities can impose on ADUs. According to the bills, local zoning ordinances cannot unreasonably restrict the creation or rental of ADUs in single-family residential zoning districts. This means municipalities cannot require special permits or other discretionary approvals for ADUs. Furthermore, municipalities cannot impose owner-occupancy requirements for either the ADU or the principal dwelling. These provisions ensure that the process of developing Accessory Dwelling Units is streamlined and transparent​​​​​​.

Except in a Few Specific Cases

While the bills seek to facilitate the development of ADUs, they do permit municipalities to impose “reasonable” regulations. These include compliance with state environmental and safety regulations, site plan review, and regulations concerning distance from property lines and the bulk and height of structures. Additionally, towns may restrict or outright ban the short-term rental of ADUs. The legislation also allows towns to require one additional parking space for the creation of an ADU, though the Senate bill notably states no additional parking is required for ADUs located within 0.5 miles of public transport​​​​​​.

Promoting ADU Development

All three bills share the common goal of promoting ADU development to address housing shortages and provide affordable housing options. They achieve this by standardizing the definition of ADUs and prohibiting unreasonable zoning restrictions. The alignment between the Governor and the Legislature underscores a broad recognition of the benefits accessory dwelling units can offer in terms of increasing housing supply . By minimizing bureaucratic hurdles , these legislative efforts aim to make it easier for homeowners to develop ADUs, creating a more flexible and inclusive housing market in Massachusetts.

Interested in building an ADU in Massachusetts? Contact me at Derek@MaaduBuilder.com for a free project consultation.