Accessory Dwelling Units


Accessory Dwelling Units


PHOENIX — The city of Phoenix has moved forward with a plan that will allow “auxiliary dwelling units,” commonly known as guesthouses, to be added to existing properties with a single-family home.

Mark Stapp, Arizona State University’s Executive Director of the Master of Real Estate Program, told KTAR News 92.3 FM’S The Mike Broomhead Show on Thursday, this change is a good move.

“I think it’s absolutely the right thing to do. But…It goes under the category of ‘every little bit helps,’” Stapp said.

The new ordinance – which has been recommended by a city council subcommittee and will be considered by the full council later – permits one “ADU” on properties with single-family units that are less than 15 feet in height if detached from the main home.

They can also be in multi-family zoning areas as long as the ADU is used for one family.

It also clarifies the differences between ADUs, duplexes, and triplexes and makes them legally distinct from each other. In any previous City of Phoenix policies, the word “guesthouse” has been changed to “auxiliary dwelling unit” as well.

Under the proposed rules, you would not be able to create an ADU bigger than 75% of the size of the main house, and no larger than 1,000 square feet if your overall property is less than 10,000 square feet.

Other rules, such as the distance the dwelling can be from the wall, may come into play depending on where you live.

ADUs can’t be built everywhere

Stapp said a single-family lot is designed and constructed for a single-family unit. The ADU must be connected to the sewer, water and electricity of the single-family unit.

And the presence of an ADU doesn’t guarantee affordability for the renter, either.

“You’re going to allow them to be developed, but it’s purely at the discretion of the property owner if they use them for affordable housing purposes,” Stapp said.

Overall, Stapp said it’s a drop in a very, very big bucket.

“I think it makes sense. But I think it’s going to have limited impact on the huge demand for affordable housing that continues to exist,” he said.

Phoenix City Councilmember Debra Stark worries that ADUs won’t benefit Valley residents who need housing, but instead be used for short-term rentals – something she says has happened in other cities.

However, city officials working on the ordinance say this policy is based on the rules in Flagstaff. There, the property owner has to be living in either the main home or ADU.

This does not outright bar short-term rentals from operating out of ADUs, but Christopher DeParro with the city’s Planning and Development Department explains the Flagstaff policy language has been successful there.

“We do believe that state law does limit our ability to put many restrictions on short-term rentals,” DeParro said.

Meanwhile, Stapp hopes this change will incite city leaders to keep looking in creative spaces to add affordable units to the Valley.

“There’s a lot of underutilized or obsolete commercial properties that are perfect for residential development. But you need to change the zoning, and we know what that means,” Stapp said.

By: Sarah Robinson

Published: Jul. 5, 2023 at 10:49 PM MST

PHOENIX (3TV/CBS 5) — If you have a shed in your backyard, you might be able to spruce it up and turn it into a rental home.

The City of Phoenix is proposing an ordinance that would allow in-law suites in backyards. The proposal is meant for families to make some extra cash by renting a small unit on their property to an in-law, a grown child, or even a stranger. “We are going through a significant housing shortage and ADUs are a low-hanging fruit solution to this issue,” Phoenix Vice Mayor Yassamin Ansari said.

Accessory dwelling units, or ADUs, are secondary housing units on a single-family lot. You might know them as casitas, granny flats, or guest houses, and they could be coming to Phoenix. “This idea has been in the works for several years now,” she said.

She says the goal is to provide renters access to affordable housing within city limits. “If the amendment passes as is, it means that anyone who owns a single-family home anywhere in the city of Phoenix can build an accessory dwelling unit in their backyard,” she said

Right now, city laws allow storage units, but not all areas allow plumbing or running water. This ordinance would change that, making the spaces liveable.

“This ordinance within the City of Phoenix is a perfect example of why the state needs to return local control of short-term rentals to cities and towns in Arizona,” said Kate Bauer, co-found of Arizona Neighborhood Alliance

Bauer says she’s scared this could create more harm than good. “We’re concerned about these turning into short-term rentals and that it won’t help the housing problem at all,” she said.

Bauer says what has really contributed to the lack of affordable housing in Phoenix is short-term rentals, like Airbnb and VRBOs. “I do believe that the ADUs could be very helpful. I absolutely do. it’s just that the cities don’t have the ability to put any sort of cap on short-term rentals,” she said.

According to state law, cities cannot prohibit or ban short-term rentals and she’s fearful some will take advantage of the ordinance to make a profit.

“The city is doing everything that it can to minimize that case through the permitting process,” said Ansari.

There are some requirements to do this: The city says you will need a special permit to build or rent an ADU, they can only be on single-family lots, and the owner has to live in the main house full time. The council is expected to vote on this in early September, and the proposal could change before then.



With an ever-growing housing crisis in the United States, many Americans are struggling to find safe, affordable housing options. Those who cannot afford a home may opt for renting. However, that option carries a lot of unpredictability and instability. Over the last five years, cities like Phoenix, Arizona have seen as much as an 80% increase in rent prices. Many growing cities simply do not have the housing supply to accommodate the influx of newcomers, let alone their existing residents. Solutions to combat this crisis are desperately needed. While no single entity can solve this crisis alone, architects and builders can bring forth new housing typologies with the goal of efficiency and affordability for residents. This article presents an introductory look into tiny homes and Accessory Dwelling Units (ADUs), two housing “trends” that have spiked in popularity in recent years, and how they can potentially become part of the solution to the housing crisis.

Tiny Homes

We’ve all heard about the “tiny house movement” by now, and it’s no question that tiny homes have made a big impact on the design world. But how can tiny homes become part of the solution to the affordable housing crisis? Typically, a tiny house is defined as a structure that is under 600 sqft, and many people associate this typology with mobility. Still, the rise of tiny house communities has proven that mobility is just a single aspect that can be associated with tiny homes, and not what defines them as such. In fact, mobile tiny homes may not be as accessible for those needing affordable housing, as there are added costs such as securing land and towing.

There are many benefits to tiny homes and tiny home communities at large. First, they are much more efficient than a typical single-family home and can reduce an individual’s carbon emissions by 70% over the course of its lifespan. They are also affordable, with the average price being just $52,000. The affordability and efficiency of tiny homes present a great opportunity to increase the supply of housing to benefit low-income and unhoused individuals. According to one study, the tiny house market is expected to grow by 3.33 billion dollars globally from 2021 to 2025.

Tiny Home Communities

As of 2019, there are 34 active tiny home communities in the United States, and one of these communities is located in Tempe, Arizona. Designed by coLAB studio, the Tempe Micro Estates are made up of thirteen 600sqf units situated around a community garden in Tempe’s Downtown Core. This development is the first of its kind in the area and showcases a design typology that is much needed in growing urban cities.

Heading northeast to Ohio is another tiny house community, known as Cedar Springs Tiny Village. This community provides the land at a monthly cost, and the resident must own their own tiny house to live there. This particular community offers lake views and plenty of walking and biking trails for its residents. While this community does charge to lease the site, they do offer a good array of amenities.

In areas of the state, like Columbus, where affordable housing is much more in demand, the story is much different. The state of Ohio currently requires houses to be 950sqf or larger, which by most standards does not meet the definition of a tiny home. Tiny homes on wheels, such as the ones that would be found at the Cedar Springs Village, are an exception because they are classified as travel trailers.

Accessory Dwelling Units

Another housing type is the Accessory Dwelling Unit or ADU for short. Many know these as guest suites, second units, or granny flats. What differentiates these from tiny houses is that they are always accompanied by a primary residence, hence the term “accessory.” They can be either attached to or detached from the main residence. Due to the rise of Euclidean zoning post-WW2, the construction of these became difficult to accomplish, but with the growing housing crisis impacting many Americans, legislation is changing to reflect the need for solutions like ADUs. A benefit of ADUs is that they can be connected to the utilities of the primary dwelling, making them more cost-efficient. Similar to tiny homes, an ADU as a primary residence can reduce an individual’s carbon footprint significantly over its lifespan. Because of their affordability and efficiency as opposed to traditional single-family homes, ADUs are a realistic option for elderly family members or young adults just starting out in the workforce who want to be closer to home but still maintain their independence.

Companies that design and build ADUs are popping up all over the western part of the country because of the legislation in place that makes building ADUs much easier than in certain states. In growing cities like Phoenix, companies are figuring out ways to make these possible and jumping on the opportunity to expand upon the types of housing that are available in their current markets. Minimal Living Concepts is a company that designs and builds ADUs in the Phoenix area. They offer a wide range of concepts that can be built from a studio, all the way up to a three-bedroom home. They use traditional construction methods over prefabricated ones because this method is easily permitted and accepted by the city.

ADU Laws

Unfortunately, ADUs remain difficult to build in many states across the US due to the fact that there are laws prohibiting them. However, with the demand for housing being so high for particular areas, some cities are coming around to creating new laws or adjusting old laws to allow for ADUs in the community. In Phoenix, residents are allowed one ADU per single-family residence, and that structure must maintain the same address as the primary residence. In 2019, the City of Des Moines changed its zoning laws to allow the construction of ADUs in certain districts as well. Currently, many parts of Ohio restrict the addition of ADUs. However, this is likely to change as they become more widely accepted in other communities.

Final Thoughts

The housing crisis in the United States is pushing demand for housing typologies that present both efficiency and affordability. This presents designers, architects, and builders with the unique opportunity to confront a large issue that has impacted so many Americans. Design typologies like tiny homes and accessory dwelling units can be a viable part of the solution to this crisis. It is only a matter of time before you might see a tiny house village or accessory dwelling unit popping up in your area.


We at Third Dimension Design, LLC are ready to help you come up with your tiny house or ADU design!