Zoning for Accessory Dwelling Units

by Amy Dain, for Pioneer Institute of Public Policy Research and Smart Growth Alliance, July 2018 (This study updates a 2004-06 study on ADUs by the Pioneer Institute.)

Even in the midst of a housing crisis, zoning laws prohibit most homeowners in cities and towns around Boston from adding accessory dwelling units (ADUs) to their single family houses. An ADU is an apartment within or behind an own- er-occupied single family house that appears from the street to be a single-family as opposed to a two-family house.

Homeowner-voters can be reassured that new rental hous- ing that could be added as ADUs would be highly dispersed and barely visible. The houses are owner-occupied; the land- lord lives next to the ADU renters, so the risk of property-ne- glect or loud parties is minimal. The houses also have to look like single family houses. Since household sizes are shrinking, new residents in ADUs might maintain current neighborhood population densities, but are unlikely to increase them.

Moreover, ADUs are permitted at such low levels now — only 2.5 permits annually per municipality where they are allowed — that permitting levels could increase substantially without being at all noticeable in neighborhoods. If the region were to average five permits per municipality per year across 100 municipalities, over a decade, ADUs could provide 5,000 apartments, dispersed among 538,000 single family houses. Less than one in 100 houses would have an ADU, yet the new rentals would house thousands of people.

Click HERE for the full report.

Accessory Dwelling Units: Policies, Attitudes in Boston Region

from Alexandra P. Levering , Thesis, Urban & Environmental Policy and Planning, Tufts University, August 2017

By 2017 65 out of 101 municipalities in the greater Boston (MAPC) region allowed Accessory Dwelling Units by right or by special permit. The average number of ADU’s added per year was about 3. But by 2017, Lexington had 75 ADUs, Newton had 73 and Ipswich had 66. It is a slow process for a variety of reasons, but the number of units grows over time.

AARP recommends ADU’s. The help homeonwers cover rising housing costs by providing income trhough rent. They also create a space for a caretaker or a family member to live close by, as the homeowner ages.

Autism Housing Pathways and Advocates for Autism of MA (AFAM) came together to advocate for an ADU bylaw to benefit parents of adult children with disabilities. For more information see her complete thesis (with a very useful set of tables and bibliography) HERE.

Accessory Dwelling Units (ADUs) provide multigenerational housing options for aging parents and for adult children. They help families manage changing lifestyle, fiscal and/or caretaking situations.

This type of housing is seen by many as a clear opportunity to offer more affordable residential opportunities. One reason why they are slow to develop is the cost of renovation and construction for homeowners. Some communities offer low or no interest loans to encourage more ADU development.