ADU Hot Topics

ADU Hot Topics

ADU 'Hot Topics' Housing

ADU ' Hot Topics'

As communities allow ADUs or update existing codes and rules to be more ADU-friendly they inevitably wrestle with the following questions

Photo by Eli Spevak The zoning code in Evanston, Illinois, permits accessory dwelling units, creating an opportunity for the owners of this 1911 home with an outbuilding in the backyard.

How can ADUs be added to existing neighborhoods

Recognizing that ADUs may represent a new housing type for existing neighborhoods, communities often write special rules to ensure they’ll fit in well. These guidelines typically address visual compatibility with the primary dwelling, appearance from the street (if the ADU can be seen) and privacy for neighbors. Rules that help achieve these goals include: height and size caps mandating that ADUs be shorter and smaller than the primary dwelling

requirements that detached ADUs be behind the main house or a minimum distance from the street

mandates that the design and location of detached ADUs be managed the same way as other detached structures (e.g., garages) on the lot

design standards for larger or two-story ADUs so they architecturally match the primary dwelling or reflect and complement neighborhood aesthetics

encouragement for the creation of internal ADUs, which are often unnoticed when looking at the house Each community can strike its own unique balance between strict rules to ensure that ADUs have a minimal impact on neighborhoods and more flexible rules that make them easier to build.

What about parking

More-realistic parking rules might: waive off-street-parking requirements at locations within walking distance of transit

allow parking requirements for the house and ADU to be met with a combination of off-street parking, curb parking, and tandem (one car in front of the other) driveway parking

What can be done about unpermitted ADUs

It’s not uncommon for homeowners to convert a portion of their residence into an ADU in violation (knowingly or not) of zoning laws or without permits. Such illegal ADUs are common in cities with tight housing markets and a history of ADU bans. One example is New York City, which gained 114,000 apartments between 1990 and 2000 that aren’t reflected in certificates of occupancy or by safety inspections. Some cities have found that legalizing ADUs, simplifying ADU regulations and/or waiving fees can be effective at getting the owners of illegal ADUs to “go legit” — and address safety problems in the process.

How can certain uses be allowed and others restricted

Communities get to decide whether to let ADUs be used just like any other housing type or to create special rules for them. Some municipalities take a simple approach, regulating ADUs just as they do other homes. So if a home-based childcare service is allowed to operate in the primary dwelling, it is also allowed in an ADU. Conversely, communities sometimes adopt ADU-specific regulations in order to avoid undesirable impacts on neighbors. Examples include: Limiting short-term rentals: ADUs tend to work well as short term rentals. They’re small and the owner usually lives on-site, making it convenient to serve as host. However, if ADUs primarily serve as short-term rentals, such as for Airbnb and similar services, it undermines the objective of adding small homes to the local housing supply and creating housing that’s affordable.

In popular markets, short-term rentals can be more profitable than long-term ones, allowing homeowners to recoup their ADU expenses more quickly. In addition, short-term rentals can provide owners with enough income that they can afford to occasionally use the ADU for friends and family.

A survey of ADU owners in three Pacific Northwest cities with mature ADU and short-term rental markets found that 60 percent of ADUs are used for long-term housing as compared with 12 percent for short-term rentals.

Respondents shared that they “greatly value the ability to use an ADU flexibly.” For instance, an ADU can be rented nightly to tourists, then someday rented to a long-term tenant, then used to house an aging parent. ADUs intended primarily for visting family are sometimes used as short-term rentals between visits.

Cities concerned about short-term rentals often regulate them across all housing types. If there are already rules like this, special ones might not be needed for ADUs. An approach employed in Portland, Oregon, is to treat ADUs the same except that any financial incentives (such as fee waivers) to create them are available only if the property owner agrees not to use the ADU as a short-term rental for at least 10 years.

Requiring owner-occupancy: Some jurisdictions require the property owner to live on-site, either in the primary house or its ADU. This is a common way of addressing concerns that absentee landlords and their tenants will allow homes and ADUs to fall into disrepair and negatively impact the neighborhood.

Owner-occupancy rules are usually implemented through a deed restriction and/or by filing an annual statement confirming residency. Some cities go further, saying ADUs can be occupied only by family members, child- or adult-care providers, or other employees in service of the family.

Owner-occupancy requirements make the financing of ADUs more difficult, just as they would if applied to single-family homes. But as ADUs have become more common, owner-occupancy restrictions have become less so, which is good. Such requirements limit the appraised value of properties with ADUs and reduce options for lenders should they need to foreclose.

Enforcing owner-occupancy laws can be tricky, and the rules have been challenged in courts, sometimes successfully. However, according to a study by the Oregon Department of Environmental Quality, more than two-thirds of properties with ADUs are owner-occupied even without an owner-occupancy mandate. This article is adapted from The ABCs of ADUs, a publication by AARP Livable Communities. Learn more below.

MORE ABOUT ACCESSORY DWELLING UNITS

Visit for links to more articles and to order AARP s free publications about accessory dwelling units

A-Z Archive

TAKE A LOOK

Watch and share this short video about the benefits of Accessory Dwelling Units.

AARP org Livable

Enter a topic, name, place, etc. See past issues:

Our Free Publications

See the complete list at

Follow Us

Facebook: Twitter:

Contact Us

Email AARP Livable Communities at .

Ask about the AARP Livability Index by completing this .

AARP Members: For questions about your benefits, AARP The Magazine or the AARP Bulletin, visit the page or call 1-888-OUR-AARP (1-888-687-2277). Cancel You are leaving AARP.org and going to the website of our trusted provider. The provider’s terms, conditions and policies apply. Please return to AARP.org to learn more about other benefits. Your email address is now confirmed. You'll start receiving the latest news, benefits, events, and programs related to AARP's mission to empower people to choose how they live as they age. You can also by updating your account at anytime. You will be asked to register or log in. Cancel Offer Details Disclosures

Close In the next 24 hours, you will receive an email to confirm your subscription to receive emails related to AARP volunteering. Once you confirm that subscription, you will regularly receive communications related to AARP volunteering. In the meantime, please feel free to search for ways to make a difference in your community at Javascript must be enabled to use this site. Please enable Javascript in your browser and try again.
Share:
0 comments

Comments (0)

Leave a Comment

Minimum 10 characters required

* All fields are required. Comments are moderated before appearing.

No comments yet. Be the first to comment!