Last week, Phoenix City Council voted to legalize backyard casitas, also known as Accessory Dwelling Units in all residential areas. It’s a small but important step forward in addressing the housing shortage which has driven up housing costs in the Valley and across the state.
Accessory Dwelling Units (ADUs) have become a major part of pro-housing reforms across the country as cities and states attempt to solve worsening housing shortages. Casitas provide additional housing to the benefit of existing homeowners. These small, backyard dwellings are typically more affordable to renters than other housing types.
The people who use these housing units are often family members: a local ADU builder writing in AZCentral says that the vast majority they build are used to help take care of aging parents.
This is a major victory for Phoenix housing advocates who worked tirelessly to get this over the line. Vice Mayor Yassamin Ansari also deserves credit for spearheading this, in addition to other pro-housing reforms she’s pushed on city council.
Much ADU about nothing
As the Arizona Agenda writes, it took immense pressure—and three years—for Phoenix to adopt just this one modest housing legalization option. They also point out that the number of ADUs produced by existing reforms in the state has been meager.
Phoenix is not the first city in Arizona to legalize ADUs. Tempe legalized casitas in 2019. Tucson passed its ADU ordinance in 2021. Tucson has completed only 37 casitas of the 77 that applied for permitting since their ordinance went into effect. Tempe numbers look much worse. Permit data from Tempe suggests the city has permitted only five casitas since 2019.
While these are housing units that otherwise would not have been produced, it is clearly not enough to make a scratch in the housing crisis. It would be tempting to dismiss allowing casitas as ineffective, but a closer look at the details of these ordinances suggests that adjustments could be made to boost production.
Learning from others
As cities and states work to legalize housing across the country, we are learning that how you legalize new types of housing is crucial.
Take California—the epicenter of the nationwide housing crisis—where ADUs were technically legal for some time, yet not built in significant amounts. Starting in 2016, a series of statewide laws passed in California that required cities to remove local restrictions on ADUs that made them infeasible to build. These included parking requirements, onerous design reviews, and expensive and time-consuming permitting processes.
The result has been an ADU boom in California. Casitas permitted increased from 654 in 2016 to 3,126 in 2017. Los Angeles, which had produced just 80 units in 2016, permitted 1,980 in 2017.
These are still small numbers in a state the size of California, but the rate of growth is tremendous. California has seen large increases every year in ADUs permitted. Now, almost one in five new housing units built in California is an ADU.
We highly recommend city planner (and friend of the blog) M. Nolan Gray’s article in The Atlantic for a comprehensive look at how California has increased ADU production.
The (sun) devil is in the details
The good news is that Phoenix seems to have passed a relatively well-designed ADU law. It does not require an additional parking space for the casita. It allows them in all single-family residential areas, although HOAs can still prohibit them. Taken together, the Phoenix plan seems comprehensively better and less restrictive than the ordinances in Tucson and especially Tempe.
Tempe’s meager ADU production is a serious cause for concern, especially given the city’s housing needs.
The problem seems to be that Tempe’s code simply does not allow casitas to be built in most places. Unlike Phoenix or Tucson, which allow ADUs in all residential zones, Tempe only allows ADUs on single-family properties within multi-family zones. Only 11% of land in Tempe is zoned multifamily (22% of all residential land) and an even smaller percentage of that land has single-family housing on it. Tempe also requires an 8,000 square foot net minimum site area, further whittling down possible areas where casitas can be built.
Tempe has at least one thing right: it does not require additional parking for accessory dwelling units. Tucson requires a parking space for each ADU unless it is a quarter mile from transit or a bike boulevard.
We have got to do more, faster
Tempe should immediately reopen its ADU ordinance and update it to allow casitas across all residential areas. The evidence suggests that when making housing reforms, it is better to have simple and flexible rules. We should limit fees, exempt casitas from setback requirements, and remove discretionary approval. The city should also put together a series of pre-approved designs to further speed up production.
There are other easy reforms beyond casitas that the city could enact. We could allow for affordable starter homes and cheaper rental units by reducing minimum lot sizes, doing away with arbitrary parking mandates citywide, and allowing other types of housing like duplexes to be built on all residential lots.
It’s unfortunate that Tempe is increasingly finding itself behind the curve on housing policy being enacted in cities and states around the country. Getting to housing affordability is going to require more than one-off solutions, it is going to require actually making substantial reforms at both the local and state levels that meaningfully increase the amount of supply.
Phoenix shows how difficult it is to pass a relatively modest reform in one city. Better late than never, but cities like Tempe and Phoenix have simultaneously been fighting state efforts to deal with the housing crisis while simultaneously dragging their feet on taking action on even the lowest of the low-hanging fruit at the local level.
Phoenix legalizing casitas is an important milestone, but if nothing else, it reemphasizes the need for comprehensive action at the state level to end barriers to housing production and affordability.
Want to write for us? We are always looking for writing about urbanism, housing policy, and related issues impacting Tempe and our state. Email us at TempeYIMBY(at)gmail.com
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