Aging parents who want to maintain a level of independence. Young adults who can’t find an affordable place to live. A person with disabilities who benefits from family support but also seeks autonomy.
What if there was a simple solution to help communities struggling with high housing costs, limited developable land and a demand for multigenerational living?
An increasing number of communities around the United States have found that there is such a solution: accessory dwelling units (ADUs). Also called an in-law suite, granny flat or secondary dwelling unit, an ADU offers an additional self-contained living unit that typically has its own kitchen, bedroom(s) and bathroom space, while maintaining independence and privacy from the primary home.
ADUs can take many forms: a second small backyard cottage on the same grounds as (or attached to) a single-family house, an apartment over the garage or a basement apartment. They offer a relatively inexpensive means to provide more affordable housing options in a neighborhood without changing neighborhood character. ADUs have the added appeal of generally not needing new infrastructure or public investment, and not contributing to a concentrated increase in density. And in addition to providing additional space for family members, an ADU may also serve as a rental unit, providing additional income for the homeowner.
According to a recent NAHB survey,
in the past 12 months, one-fifth of remodelers created an ADU by converting an existing space; a similar number also created an ADU by building a new addition. More than 75% of remodelers indicated such projects cost upward of $50,000 to construct, with only 6% completing projects valued at $25,000 or less (or what is often considered a minor improvement).
Here are how communities across the country are integrating these solutions:
After strong advocacy from the New Hampshire Home Builders Association
, with a broad coalition of housing advocates, including Housing Action New Hampshire
and New Hampshire’s Business and Industry Association
, New Hampshire passed an ordinance in 2017 that requires local zoning ordinances to allow ADUs
nearly everywhere that single-family houses are permitted.
The New Hampshire law prohibits communities
from requiring that the units have fewer than two bedrooms, be smaller than 750-square-feet or that a person related to the owner live in the ADU. However, towns and cities may require that one of the units is owner-occupied. Local municipalities also have oversight over parking requirements, and can limit ADUs to one per home and institute design guidelines.
Researchers have suggested that small-scale infill development such as ADUs could account for as much as half of California’s new development capacity
in coming decades. Effective Jan. 1, 2018, California adopted legislation to support the development of ADUs
alongside a primary single-family residence along with easing parking restrictions and fees from utilities.
San Francisco has also pioneered carving ADUs out of existing apartment buildings
. New units are being created out of garages, storage spaces, even vacant boiler rooms. San Francisco’s regulatory innovations have helped to add hundreds of new ADUs to the pipeline since 2017.
The keys to success of San Francisco’s ADU regulations include:
- Fast-tracking plan reviews
- Adding flexibility to city guidelines, and
- Cultivating lender and industry support.
Such measures would easily help encourage the development of ADUs elsewhere, too.
Over the last five years, both of the Twin Cities have explored how to increase housing diversity and add density in residential neighborhoods. Minneapolis and St. Paul demonstrate different paths to advance access to ADUs
: one fast track, the other slower.
- In 2014, Minneapolis introduced an ordinance to allow all types of ADUs — internal, attached and detached — to be built on single- and two-family lots throughout the city. The only requirement was administrative review for compliance. The initiative yielded quick interest, and in the first three years, building permits were issued for 92 ADUs.
- In 2013, St. Paul undertook a more incremental, neighborhood-based approach to pilot ADUs in particular neighborhoods near the Green Line light rail. After extensive public input and review, a 2016 ordinance established the total area permitted for ADUs in a 3.5-square-mile area on either side of the light rail corridor. However, St. Paul’s piecemeal approach appeared likely to result in allowing ADUs in one neighborhood but prohibit them just a few blocks away. In 2017, only one ADU was permitted for construction. Major points of discussion on ADUs in St. Paul included a preference that primary properties be owner-occupied and how the units would be inspected. Finally, in 2018, the Paul City Council voted to allow ADUs on single-family lots throughout the city.
As the need for this type of housing stock is in higher demand around the country, localities and states have sought to find ways to overcome barriers and make ADUs a more widely available option. Fortunately, the growing popularity means there is now a wide array of data, ordinances, and best practices on record.
For additional information on ADUs and other affordable housing options, NAHB has recently published a new research report, “Diversifying Housing Options with Smaller Lots and Smaller Homes
,” which is also available through the Land Use 101
and Housing for All
Deborah Myerson is the executive director at South Central Indiana Housing Opportunities (SCIHO) in Bloomington, Ind. Read the full post on Best in American Living.