MAPC presents
Photo Credit: Union Studio Architecture and Nat Rea Photography
There are many types of homes that would provide more housing options for smaller households while maintaining compatibility with the small-town character of suburban and rural communities in Greater Boston. Living little explores seven of these types:
Photo Credit: Alexis Smith
There’s more to Greater Boston’s housing crisis than simply a lack of affordable housing. In the region’s suburbs, where most homes are single-family detached houses, there is also a lack of different types of housing, which leads to a mismatch between available housing options and the needs of the people who live there.
If so many people want smaller housing options, why does it seem like huge, expensive houses are the only things being built in many suburban towns? This video breaks down housing costs and the ways that local policy can encourage or discourage certain types of housing.
In most suburban neighborhoods, it’s no longer legal to build modest homes like duplexes or backyard cottages. But these rules can be changed!
An Accessory Dwelling Unit, or ADU, is a smaller apartment on the same lot as a larger main house. ADUs are also known as “granny flats,” “carriage houses,” or “in-law apartments.” ADUs can be within the existing house (for example, in a finished basement), added to an existing structure (for example, in space above the garage or as a small addition to the main house), or free-standing (for example, in a converted a carriage house).
Photo Credit: Sightline Institute
ADUs were prevalent before World War II throughout American towns and cities, often housing in-laws, extended family members, or household staff. Following the end of WWII and the move towards single-family development, low-density suburbs, and increased zoning restrictions, ADUs lost popularity or were zoned out of existence. Beginning in the 1970s, a handful of municipalities began to write ADUs back into their zoning, recognizing ADUs as one solution to high housing costs. Nationally, Oregon and California are at the forefront of creating flexible zoning to encourage ADUs.
ADUs can vary widely in size, from as small as 250 square feet to as large as 1,200 square feet. Towns often limit the size of the ADU overall, or in relation to the main house (for example, the ADU cannot be larger than 30-40% of the main house’s area), to help ensure it is relatively lower cost. Building codes require an ADU to have its own bathroom, kitchen, and bedroom, separate from the main house.
How can my town's sewer system handle this?
The small size of ADUs makes their impact on public infrastructure minimal, especially when compared to large single-family homes or multifamily dwellings. For example, the impact of ten ADUs with two people living in each would have the same impact as that of four large single-family houses with five people living in each.
If my neighbor builds an ADU, will my property values go down?
That's unlikely. There is no conclusive evidence that ADUs negatively impact property values; on the contrary, ADUs can increase surrounding property values. Zoning bylaws can also be crafted to ensure the design of ADUs is in keeping with the surrounding neighborhood. [1]
What if these increase the number of schoolchildren in town?
ADUs' impact on school system enrollment is usually very small, because ADUs are overwhelmingly occupied by small households without school-age children. [2]
Chapple, Karen. Studying the Benefits of Accessory Dwelling Units. UC Berkeley.
City of Reno. Accessory Dwelling Units, Neighborhood Advisory Board Presentation.
Hulse, Travis M. Use of Accessory Dwelling Units as a Housing Strategy: A Case Study of Lawrence, Kansas. University of Nebraska - Lincoln.
ULI. Accessory Dwelling Units: Friendly Density or Neighborhood Foe?
Garcia, David. ADU Update: Early Lessons and Impacts of California's State and Local Policy Changes. UC Berkeley.
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