Accessory Dwelling Units: Lessons for Massachusetts from Around the Country

Any opinions expressed in this paper are those of the author(s) and not those of the Joint Center for Housing Studies of Harvard University or of any of the persons or organizations providing support to the Joint Center for Housing Studies. [...] Design standards, moreover, must be “clear and objective.”62 The approach taken in Portland and then in the state as a whole has made Portland and Oregon models for other states that seek to encourage and support the development of ADUs (though, as of mid 2023, only California, Washington, and Montana, have come close to Oregon’s policy of banning owner-occupancy requirements and most parking requ. [...] Additionally, the absence of consistent standards for ADUs in New Hampshire has stymied the growth of a network of builders and developers who specialize in ADUs and forestalled the emergence of innovative ways to fund ADUs. [...] The city also offers grants up to $2,500 for design costs and $45,000 for construction costs to each homeowner who participates in the affordable ADU program.105 In contrast, Boston provides up to $50,000 in zero-interest, deferred loans to homeowners who want to create an ADU and whose incomes are less than 135 percent of the AMI.106 An Emerging ADU Ecosystem In addition to the changes in local r. [...] With these provisions, the number of ADUs permitted in the state rose elevenfold in six years, increasing from 1,269 in 2016 (when new ADUs accounted for about one percent of all new housing built in the state) to over 24,000 in 2022 (when new ADUs accounted for about 18 percent of all new housing in the state).122 Comprehensive or Incremental Change? The research also makes it clear that those in.