10 Ways to Kill an ADU
(and How to Fix Them)
By Garlynn Woodsong and Izzy Davids, Woodsong Associates, LLC
ADUs can liven up a community, replacing underutilized space, such as excess driveway area, with cute new homes!
While living in a detached single family home has its appeal, the land, water, and resources that it uses, plus the astronomical costs of purchasing or renting a home, make it an unsustainable option for many homeseekers, as well as for the environment. Accessory Dwelling Units (ADUs), also known as in-law units, backyard cottages, granny flats, and a plethora of other names, offer a way to expand housing options within single-family zoning (SFZ), creating smaller, more affordable homes without drastically changing neighborhood character. These homes are perfect for smaller households who still want to enjoy the benefits of SFZ, or in places where multifamily housing is scarce.
New legislation in the past decade has legalized ADUs for millions of homeowners nationwide, opening the door for much-needed “missing middle” housing. However, regulatory barriers and red tape still stand in the way of ADU adoption, limiting what homeowners can build and discouraging their production.
At Woodsong Associates, we have worked nationwide to help cities, counties, and states refine their ADU policies and streamline the permitting process. Our expertise helps jurisdictions clear these roadblocks so that property owners can more easily build ADUs, providing affordable, sustainable housing while strengthening their communities.
10 Ways to Kill an ADU (and How to Fix Them)
Parking requirements
Many jurisdictions across the country require every new detached ADU to provide (at least) one on-site parking space, which can be particularly burdensome in urban areas where space is limited and land costs are high. For homeowners looking to add an ADU, at best this can mean having to pave over a portion of their yard, or make other costly modifications to their property, ultimately increasing the expense and complexity of the project. For many properties, especially those on smaller lots, it may not be physically possible to add additional off-street parking spaces; for these properties, parking requirements can effectively kill any potential for adding an ADU.
Moreover, minimum parking requirements can be especially problematic in dense neighborhoods where public transportation options are readily available. These requirements not only discourage or prevent the creation of new ADUs, but also undermine broader urban planning goals aimed at reducing car dependency and promoting sustainable, walkable communities.
By requiring unnecessary parking spaces, municipalities inadvertently stymie efforts to increase affordable housing options and make better use of existing residential properties.
Alternatively, by eliminating or reducing parking mandates, cities can encourage more ADU development, while promoting sustainable, walkable neighborhoods.
Has your jurisdiction considered parking requirement reductions? Woodsong Associates can help you develop smart parking policies that balance mobility needs with housing growth.
2. Architectural compatibility requirements
Some jurisdictions’ zoning codes require new ADUs to be “architecturally compatible” with the main home, forcing property owners to try to match the colors and materials of their ADU to their existing house. While this regulation is meant to protect neighborhood character and maintain a cohesive aesthetic, it ends up being problematic for a number of reasons.
First, it can add significant costs to an ADU project, especially if the main home’s materials are expensive, discontinued, or hard to find.
Moreover, what should a homeowner do if they don’t like the aesthetic of the main home? Should they be forced to choose between spending hundreds of thousands of dollars replicating a look that they don’t like, or instead, forgo building the ADU only because the law says that it has to match?
Finally, architectural compatibility requirements directly contradict many states’ and jurisdictions’ requirement that an ADU must go through a ministerial review process based on objective standards, meaning all considerations must be completely free of the need for subjective determinations. Assessing “compatibility” calls for a subjective determination, allowing for delays in the permitting process and unfair treatment of ADUs, depending on who is reviewing their architectural “compatibility.”
The State of California clarified this statewide regulation with the passage of new ADU bills in September of 2022, stating that all ADU standards must be objective (SB 897). However, some California cities, such as Buena Park, have gotten around the new law by updating their ordinance to require ADUs to “incorporate the same architectural features, building materials, and color as the main dwelling unit.” This language allows the City to claim that its ordinance conforms with State law, though it continues to pose the same hindrance as the previous “compatibility” language. Lacking specific legal guidance to cities from HCD concerning the inapplicability of design compatibility requirements to ADUs, they remain a barrier to ADUs in many California jurisdictions.
The State of Oregon, on the other hand, has issued guidance to its local jurisdictions to clarify, in its Guidance On Implementing The Accessory Dwelling Units (Adu) Requirement Under Oregon Senate Bill 1051, that:
“Any design standards required of ADUs must be clear and objective (ORS 197.307[4]). Clear and objective standards do not contain words like “compatible” or “character.” … Requirements that ADUs match the materials, roof pitch, windows, etc. of the primary dwelling can create additional barriers to development and sometimes backfire if the design and materials of the proposed ADU would have been of superior quality to those of the primary dwelling, had they been allowed. … We suggest that cities can set objective design standards to protect the look and feel of neighborhoods, but that they shouldn’t be based around matching the main home.”
California, and every other place that wants to truly incentivize the construction of ADUs, should follow Oregon’s lead, and eliminate design compatibility requirements for ADUs.
Our team has worked with cities to craft legally sound, objective ADU design guidelines that avoid unnecessary costs while ensuring good urban design. Let us help you create a practical, enforceable ADU ordinance.
3. Front setbacks
Often, ADUs are only legally allowed to be placed in side or rear yards, rather than in a home’s front yard. Many jurisdictions require ADUs to comply with the underlying zoning’s front setback requirement, which is often between 10 and 30 feet. This requirement allows homeowners to preserve their front yards, although it also means that for external ADUs (not converted from existing living space inside the home), a significant portion of the home’s private backyard is consumed by the ADU’s footprint. Hence, front setback requirements may prevent some homeowners from building an ADU, as they don’t want to give up their valuable backyard space, or lack sufficient backyard space entirely, but aren’t permitted to place an ADU in the front yard.
Existing carriage houses tend to fade into the fabric of the neighborhood.
In California, the 2022 ADU bills added an exemption to allow people to build an ADU of up to 800 square feet in the front yard, if there was no feasible space in the side or rear yard (AB 2221). While this was a step in the right direction, removing the setback requirement altogether would reduce uncertainties for homeowners, and allow them to build ADUs of any legal size that they can fit in the front yard or driveway, if they so wish. Legalizing ADUs within the front setback would also legalize a classic American typology, the carriage house, which places an ADU above a garage to accommodate both parking and housing in the same structure.
Is your city missing an opportunity to allow ADUs in underutilized front setbacks? Woodsong Associates can help evaluate the impact of setback reforms and craft policy updates that align with state housing laws.
4. Lengthy permitting processes
If you talk to anyone who has built, or is in the process of building an ADU, there’s a good chance they will have grievances to share about interminable permit processing and plan review timelines by their city or county development review staff. Despite often being a by-right development type, ADUs often go through two phases of permit review: first by a jurisdiction’s planning division, then by their building division (as well as, potentially, engineering, fire, water, sewer, and other utility divisions; in some instances, external review is also required by private utilities and/or by schools to assess fees). These reviews may or may not happen concurrently, and can each take weeks or even months to complete, particularly when revision periods are factored in.
Some jurisdictions require part or all of the permitting process to happen in person, which can delay it even further, thanks to limited opening hours and staff capacity.
Long permitting times can end up adding significant costs to the design/construction process, deterring homeowners from wanting to build an ADU. While it takes time and effort to revamp a jurisdiction’s permitting process, a streamlined, concurrent, fully online permitting framework can ease the burdens of ADU development for both city/county staff and homeowners. One city, San José, California, has gone much further with its permit review process streamlining efforts: it now offers the opportunity to issue same-day permits on “ADU Tuesdays,” for the placement of pre-approved ADU designs on uncomplicated sites.
We specialize in process streamlining. If your city wants to reduce permitting bottlenecks, we can help implement online approvals, pre-approved ADU plans, and fast-track review systems.
5. Few available financing products
Because ADUs are a relatively new type of housing product, most conventional banks and lending institutions that offer mortgages don’t yet offer an ADU-specific financing product, making it challenging to access construction financing to build one. Many property owners rely on cash savings, loans from friends and family, or leveraging the equity that they have in their property to take out a Home Equity Line of Credit (HELOC) or home equity loan. However, if a property owner doesn’t have access to any of these options, or if they hope to construct an ADU around the same time that they buy a home and don’t yet have enough equity built up to do so, they may not be able to build one.
If more banks, especially community-serving institutions like Community Development Financial Institutions (CDFIs) and credit unions, were to create ADU-specific financing products, this would help a wider range of people to build their own ADU and create a new revenue stream for themselves, particularly those who have been historically limited from accessing financing.
Moreover, cities, counties, regions, joint powers authorities, states, or even the federal government could create ADU financing programs, such as grants and low-interest loans to help lower-income households build ADUs, as well as a secondary market to sell ADU financing notes into after they have been issued by a primary lender.
Granting the opportunity to build an ADU and become a landlord to socioeconomically disadvantaged groups and individuals can be an effective way to advance equity and generational wealth building, while also providing desperately needed housing.
Woodsong Associates advises governments and financial institutions on ADU-friendly financing solutions. Let’s work together to create funding pathways that make ADUs attainable for more homeowners.
6. Confusing and unclear requirements
Similarly to long permitting timelines, confusing requirements for applications, architectural plans, fee payments, and inspections can be one of the most frustrating parts about building an ADU. Since ADUs are relatively new to many places across the country, many jurisdictions have yet to develop comprehensive resources detailing the steps required to build one legally. This confusion, coupled with the long permitting timelines and costly permitting fees, compels many homeowners to forego obtaining permits, and build their ADU illegally instead. This can be dangerous for future tenants of the unit and property owners, as tenants could face eviction, and property owners could face serious legal consequences, if found out by the jurisdiction’s code enforcement department. While going through the permitting process can cause headaches, completing it properly ensures that the unit is legal and safe for habitation. If the unit doesn’t comply with the building code in effect, it can pose serious threats to the health and safety of the people living in it. It can also complicate efforts to properly insure the home, can prevent the ADU from being used to support a higher resale value, could complicate efforts to sell the property, and likely would prevent the local jurisdiction from being able to collect additional property taxes on the additional value that an ADU adds to a property.
To ensure the safety of the community, it is thus imperative that jurisdictions make the permitting process as easy and straightforward as possible, so that as many unpermitted ADUs as possible are prevented. Resources like handouts, checklists, fee schedules or calculators, and permit process diagrams can clearly inform the public about all of the steps that they need to take to legally build an ADU and prevent dangerous code violations. Moreover, a clear understanding of the permitting process can be encouraging to those who are on the fence about building an ADU, leading to an overall boost in their production. Boosting ADU production should logically lead to a boost in property tax revenues for local jurisdictions, meaning there is a payoff to the local jurisdiction for development review streamlining efforts beyond the initial fees collected for permit issuance.
We help cities create clear, user-friendly ADU guides, process diagrams, and fee calculators. Need a comprehensive ADU handbook? We can develop one for you.
7. Bans on two-story ADUs
What if an ADU could provide double the amount of livable space, while only using the same amount of yard space? Well, with two stories, it easily could. However, two-story ADUs are prohibited in many jurisdictions across the country, despite being a fantastic way to maximize both indoor and outdoor living space.
Moreover, while California’s statewide ADU regulations allow local jurisdictions to permit two-story ADUs, the majority continue to limit them to a single story in most cases. The suite of ADU bills that California passed in 2022 added some exemptions that require jurisdictions to allow two-story ADUs in some cases, including all attached units, and those within walking distance of a high-quality transit stop (SB 897), but most new detached ADUs are still limited to a single-story in height.
Permitting two-story ADUs by-right (or, perhaps, two stories above a garage) would allow thousands of homeowners with smaller lots the opportunity to build larger ADUs that can generate more revenue and can house more people. This is an obvious step in the right direction to solving the housing crisis. As larger ADUs contain more square footage, they would also produce more property tax revenue, meaning a fiscal payoff to any local jurisdiction that allows 2+ story ADUs.
Curious about how height limit adjustments could increase ADU production in your community? We can analyze your zoning code and recommend smart policy updates.
8. Lower than necessary square footage limitations
We typically think of ADUs as miniature homes, much smaller than a regular single-family residence. Oftentimes they are, yet there is a great opportunity to build larger units of 1,000-1,200 square feet that more closely resemble the size of a standard house, including additional bedrooms, bathrooms, work areas, and common space. Since ADUs often have streamlined permitting requirements (i.e., ministerial review), they are typically easier to build than a new detached single-family home, which usually passes through a lengthy discretionary review process. Therefore, by building larger ADUs, property owners can construct a unit that can fit bigger families or households. This can combat overcrowding and help to balance the housing market.
However, many jurisdictions limit the size of ADUs to 800 or 1,000 square feet, even when their state may allow them to be built up to 1,200 square feet. If jurisdictions raise the maximum square footage limit to 1,200 square feet or more, homeowners with ample yard space could build housing units that fit entire families of three, four, or even five members, greatly expanding the versatility of ADUs as a housing solution, including for multi-generational households.
Does your local ADU ordinance reflect the full range of housing needs? We can assess and refine your policies to maximize their impact.
9. High impact fees
Impact fees are designed to offset the municipal costs associated with population growth, such as for providing more parks, schools, or transportation infrastructure, and they are charged to most new residential and commercial developments in some form. As a city or town gains new residents or patrons, it stands to reason that it may pay more to provide services to those people, such as for the maintenance of streets, sidewalks, parks, vegetation, and public facilities, such as schools. While these fees are clearly important for sustaining complete communities that serve their residents, they can also become quite burdensome to property owners wishing to construct an ADU, if left unchecked.
Sometimes, fee structures can allow impact fees to reach astronomical rates. For example, the California city of Buena Park charges a “park in-lieu fee” to fund the maintenance and creation of local parks, which is based on a formula using the floor area ratio between the main home and the ADU, as well as the market value of the land. Because of the formula’s structure, in some cases, the park in-lieu fee has reached more than $19,000 for a 999 square foot ADU. For comparison, another ADU of only 250 square feet less was charged a fee of about $9,000, less than half the cost. This example shows that the way a fee is structured can dramatically impact the cost to construct an ADU, and thus, its long term profitability (or, the ability to cover its own costs and expenses, plus produce some sort of financial incentive to the owner in return for the brain damage required to design, permit, finance, and construct the ADU).
California law requires all jurisdictions to conduct an impact fee study to ensure that all impact fees are proportionate to the cost of providing the service, but many jurisdictions are out of compliance, and it seems that consequences for failing to comply are minimal to none. To ensure that ADU owners aren’t paying more than their fair share for city services, and thus discouraging the production of ADUs, we recommend stronger legislation at the state level to incentivize or require jurisdictions to re-assess their impact fee exactions. At the local level, we recommend that jurisdictions consider the balance between the potential income that can be raised by fees, in comparison to the potential lost property tax or other revenue from ADUs not built due to excessive fees that may discourage their production.
We can conduct an impact fee analysis to ensure fees are proportional and legally defensible, while still funding essential infrastructure.
10. Bans on Tiny Homes on Wheels (THOWs)
Bans on Tiny Homes on Wheels (THOWs) represent a significant barrier to the development of ADUs, particularly for those seeking flexible and affordable housing solutions. THOWs offer an innovative approach to providing housing: a compact, mobile living space that can be an ideal solution for many homeowners looking to add an ADU. However, many municipalities impose strict regulations or outright bans on these types of dwellings, citing concerns ranging from safety standards to neighborhood aesthetics. These bans prevent homeowners from utilizing THOWs as a viable option for creating additional living spaces, thus limiting the potential for diverse and affordable housing within the community.
The prohibition of THOWs often stems from outdated zoning laws that fail to recognize the evolving needs and preferences of modern residents. By restricting these adaptable and cost-effective housing solutions, local governments not only stifle innovation, but also miss out on opportunities to address housing shortages. Allowing THOWs can enable more homeowners to contribute to the housing supply, offering an accessible pathway for those who might not have the financial means to construct a traditional ADU. Therefore, lifting these bans and implementing reasonable regulations could significantly enhance the flexibility and inclusivity of housing options in many communities.
Portland, Oregon is one community that eliminated its ban on THOWs, beginning in 2019. It now allows homeowners to park a THOW in their driveway or other legal parking space, as long as it is provided with properly permitted utility hook-ups for sewer, potable water, and power. The general consensus of residents seems to be that allowing THOWs in driveways is vastly preferable to having to deal with homeless campers in tents and RVs on the streets and other neglected areas of the city.
If your city wants to explore THOW legalization, Woodsong Associates can help craft zoning updates that ensure safety while allowing this innovative housing option.
Moving forward
Given the critical state of the country’s housing market, with crippling shortages of housing in most in-demand areas, ADUs provide an essential type of homeowner-initiated housing that can be leveraged to boost the overall stock of homes, and bring down costs for everyone. Their versatility allows them to work for a multitude of situations, both for homeowners interested in building their own, and for tenants seeking housing for small or larger households. However, unnecessarily stringent zoning requirements, onerous permitting and construction processes, and lack of access to financing can prevent or discourage property owners from constructing their own, further prolonging the housing crisis.
At Woodsong Associates, we partner with cities, counties, and states to streamline ADU programs, develop financing solutions, and update zoning codes to support ADU production.
If your jurisdiction is ready to unlock the full potential of ADUs, let’s talk. Contact us today to see how we can help make ADUs work for your community.
