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Dave Marshall and Kasey Cordell at their home on Monday, August 30, 2021, near Berkeley in Denver. The couple, looking to turn their basement into a rental dwelling unit, has gathered numerous neighbors to initiate a group application for the ADU zoning process. (Olivia Sun, The Colorado Sun)

Dave Marshall can stand on the front porch of his circa 1939 bungalow on the north side of West 46th Avenue in Denver’s Berkeley neighborhood and point to multiple accessory dwelling units — also known by terms like granny flats, mother-in-law apartments or carriage houses —  that dot the lots on the blocks to the south. 

But on his side of the historic parkway, city zoning hasn’t allowed them, owing to smaller lot sizes. So Marshall and his wife, Kasey Cordell, decided to pursue rezoning their property to open up the possibility of creating an ADU in their little-used basement — or if that didn’t work, atop their garage. 

When Marshall reached out to the city for guidance, officials offered a time- and money-saving suggestion: gauge interest among his immediate neighbors and then join forces with others interested in rezoning their property. A single application would save filing costs — each application runs about $1,000 — and also streamline the city’s response.

As a result, 11 of the 15 homeowners along that stretch of 46th Avenue now have joined Marshall’s application for rezoning, while another is pursuing it on their own.

For Marshall and Cordell, their own reasons reach beyond the practical or financial advantage of having a separate living unit to a more expansive vision of the big-picture role that ADUs could play in creating so-called “gentle density” that could make housing more affordable in the city.

“We really believe in what the ADUs are intended to do for the city,” Marshall says. “We’re a big fan of not encouraging growing sprawl where people have to live out in Erie or Firestone, because there’s just not enough housing inventory. So we’re in favor of smart development, that looks at ways to increase density — not a green light for everyone to do whatever they want, but smart ways to encourage people to utilize their space more productively.”

Interest in ADUs rose steadily in the 2010s, and has only grown stronger in the past few years as the metro-wide real estate market became, for many, prohibitively expensive. City planners have seen an uptick in people moving to rezone their property, and in 2019 carved out a place for ADUs in Blueprint Denver — a “planned guidance” document that recommends removing barriers to the units in residential districts. So far, planners say, they’re not aware that any requests have been denied.

Meanwhile, elected officials like District 1 Councilwoman Amanda Sandoval have shepherded entire neighborhoods — most recently Sloan’s Lake and before that, Chaffee Park — into the ADU zoning fold, another recommendation of Blueprint Denver. Those legislative moves made that option possible for about 3,000 properties.

In District 3, Councilwoman Jamie Torres is exploring similar rezoning for the Villa Park, Barnum and Barnum West neighborhoods, where more than 2,000 lots could be added.

The West Denver Renaissance Collaborative, which aids equitable neighborhood revitalization, continues to advance ADUs by working with public, private and nonprofit organizations to help finance and build units. The group has three currently under construction, two in the permitting process, and up to four more in the financing/underwriting phase and preparing to head into final design. 

“Our goal this year is to get 10 units into the pipeline and into construction,” says Director Renee Martinez-Stone. “Beyond those 10, at least another 20 are very interested in exploring the possibility of working with us.”

Interest is definitely spreading, particularly in the denser urban core, but interest also appears to be growing in the outer rings of the city, says Josh Palmeri, a senior city planner for Denver.  That said, he notes that barriers still exist — starting with a cumbersome and expensive rezoning procedure that can take as long as nine months. After seeing many people express interest but then get put off by the process, city planners are kicking off a project this month to seek ways to eliminate some barriers and explore how ADUs fit various kinds of Denver neighborhoods. 

HOW TO PARTICIPATE: Click here to express interest in the ADUs in Denver project.

“We’re definitely seeing an uptick in the rezoning,” Palmeri says, “so we feel as a city that it is definitely gaining momentum.”

That momentum is reflected in the rebounding number of rezoning requests, which took a hit during the COVID-19 pandemic. In 2010, Denver issued only two ADU permits. In 2019, the number spiked to 71 before the coronavirus shutdown saw a dropoff to 54 in 2020.

So far this year, 32 ADU permits have been issued. 

Dave Marshall and Kasey Cordell at their home, in Denver’s Berkeley neighborhood. The couple stands by a door that could be the private entry to an accessory dwelling unit in their basement. They gauged interest from neighbors and wound up submitting a rezoning application for 11 of the 15 homes on their block. (Olivia Sun, The Colorado Sun)

Rezoning by neighborhood

About one-fourth of Denver’s cityscape, not counting the airport, is currently zoned to allow an ADU. But spurred by guidance from Blueprint Denver, urban enclaves are pursuing rezoning to accommodate them not just through one-off applications, but in large neighborhood-sized chunks.

“My thought is if you provide the zoning to everybody, then one of the barriers is taken down,” Sandoval says. “And when they don’t have to worry about going through that process, they can hire an architect and start building. So, providing the zoning makes it an equal playing field for everybody.

“When you do one-off zoning, it’s time consuming. It seems more expedient and time efficient to rezone and re-do a whole neighborhood with that process, instead of one neighbor, then the next neighbor.”

That doesn’t mean an ADU goes up on every property. In surveys that Sandoval’s office has done to gauge interest in rezoning, she asks: Would you build now? Most people say no. But there’s also a built-in equity element to rezoning an entire neighborhood. That potentially prohibitive cost for an individual application disappears.

High construction costs still present challenges. But ADUs’ role as a mitigating factor in the current housing crunch speaks to changing attitudes toward higher density development as a desirable shift that adds to the ability of local workers to live near their jobs.

“We’d love for a bartender who works on Tennyson, or restaurant workers, school teachers who work in this neighborhood to be able to afford to live in the neighborhood,” Marshall says. “There’s also a community component when you bring a mixed, diverse group of people into your community. We’re big fans of the city’s intent to do that.”

Residents from Chaffee Park, in far northwest Denver, approached Sandoval about rezoning for ADUs once she was elected to city council in 2019. The decision to pursue a zoning change for Sloan’s Lake followed a more data-driven approach, she explains.

Research showed that to be the neighborhood with the most one-off rezoning requests. So her office sent residents flyers through the mail surveying their attitudes about ADUs. Then she hosted two town halls, where residents could learn the basics — what ADUs are, how many permits had already been pulled, what neighborhood impact can look like. Sandoval also sought input from utilities, the city assessor and fire and transportation officials.

Then came another round of flyers — this time placed directly on residents’ doors, to further gauge interest. Outreach continued until a statistically valid pool of responses had been collected. Then her office analyzed the data — 334 residents responded, nearly 95% homeowners — and presented it to the planning board for review and ultimately consideration by the city council.

More than 73% of respondents favored rezoning to allow ADUs, with 20% opposed. Nineteen percent said they’d move to build immediately, 34% said they didn’t intend to build and 46% said they might build in three-to-seven years.

Recently, Sandoval has been hearing interest from the Regis neighborhood, just west of Chaffee Park. That could be the next area where she explores bulk rezoning.

The process inevitably reveals pockets of concern — and sometimes confusion, she says. People worry that the rezoning would allow more apartment buildings or duplexes. They worry about parking, about privacy in their backyards.

“I think northwest Denver has seen so much change in the built environment that people are concerned about change,” Sandoval says. “It’s about education, right? The more education you can do to inform constituents what an accessory dwelling unit is, and show them examples within their own neighborhood, I think people start to understand it in a different way.” 

Beth and Geoff Gallinger built this two-story garage, seen from the second floor of their primary residence, with the idea that they might one day seek a zoning change to allow its conversion to an ADU. Through an error in construction, the garage ended up being too tall. Rather than trim several inches off the roof, they decided to seek ADU zoning that would allow for the structure as built. (Olivia Sun, The Colorado Sun)

Finding help with the process

Sandoval’s office also has offered assistance to homeowners in other neighborhoods within her district who want to pursue rezoning on their own.

When Beth Gallinger and her husband, Geoff, moved into their house in the Denver’s Highlands neighborhood back in 2016, they had big plans to make the 600 square-foot bungalow work for the long haul. 

First, they revamped, expanded and upgraded the existing structure — created a new house, for all practical purposes. Along the way they added a detached garage, with the idea that — someday — they’d convert it to an ADU. 

So the two-story garage went up and, while the Gallingers waited for the day when they might seek the one-off rezoning to allow for inhabitants, they used the second floor for storage. But when city inspectors came to look at the garage, they discovered that the builders goofed.

A misplaced beam caused it to exceed height limitations by 9-1/2  inches. They kicked around ideas for how they could trim off the excess height to make it comply, but then realized that the garage, as built, would be well within the specifications for an ADU. All they had to do was change their zoning.

“It kind of forced our hand in rezoning our property before we had planned on it,” Beth says. “So we decided, all right, we’re gonna go for it, we’re gonna apply and we’re gonna do it. How hard could it be, right? 

“We learned very quickly, very hard. I feel like it’s a very confusing process. That’s why you have to find somebody at the city who can basically guide you through this.”

For the Gallingers, Sandoval’s office provided that guidance. The conversion of their garage to an ADU became roughly a three-year process, in part because they adopted a son, David, along the way and decided to pause everything while they recalibrated family life. So the garage issue remained unresolved until they felt ready to revisit the process in January of 2020. Three months later, COVID-19 struck and slowed everything down still further.

They finally got word that their rezoning application had been approved last December — they considered it a surprise Christmas present. So now they’ve been pursuing all the appropriate permits to transform that upper level into a livable space.

“Short term, we were actually thinking like family,” Beth says, “because you know we have a new little boy in our life and when in-laws come to town there’s only so much traffic you can handle in your house. But we were kind of thinking long term about making it a rental.”

Joey Gargotto, a 30-year-old commercial real estate broker who bought into Denver’s West Highlands neighborhood, watched as the homeowner next door went through the rezoning process and then constructed an ADU above a three-car garage. Gargotto totally supported his neighbor’s plans — and also took note of the process so he could start down that road himself.

With a wedding planned for next fall, he and his fiancée look ahead to a time when a larger family and visiting relatives would make an additional living space an attractive option. So they spent about $1,250 for the application, the signage informing neighbors of his intent and letters to his immediate neighborhood delivering notice.

But that’s as far as they’re ready to go at this point.

Beth and Geoff Gallinger with their son, David, in northwest Denver. They had thought of one day converting the garage they built into an ADU, but a construction error prompted them to seek rezoning sooner than they originally planned. (Olivia Sun, The Colorado Sun)

“Now that we have zoning in place, for us we feel like it gives us the ability to think about our home as more of a long-term thing,” Gargotto says. “Now that the zoning’s in place, we can think about what improvements make to the home, but also think about bearing the cost of the ADU, because being 29 and 30, we’re not in a place to start building this out.”

He became familiar with Blueprint Denver and supports the need for adding density and, at the same time, addressing the city’s housing supply problem. Even though he sees a “fair amount” of ADUs functioning as short-term rentals — including the unit next door — he notices only a “minor change” in the parking situation and considers that a minor issue.

“I’m seeing a lot of pressure to maintain the neighborhood feel, at the same time there’s a real affordability issue,” Gargotto says. “Frankly, those issues are in direct competition. We’ve decided this is the context we feel comfortable with as a community, this is a good compromise.” 

Construction costs remain high

But even moving beyond concerns about issues like parking and neighborhood character, construction continues to present a potentially difficult barrier.

Bill Killam, a 35-year resident of the Berkeley neighborhood, started pursuing an ADU when he had the opportunity to purchase a neighboring property in 2007. But the recession paused that idea for about five years, when he then began working with a builder on constructing a large garage with a second-floor ADU. He didn’t break ground until 2017.

A year later, he put the 1,000 square-foot, two-bedroom, two-bath unit on the short-term rental market. One lesson learned: It’s not easy, or cheap, to build a fully functional ADU.  

“There are a lot of very tricky design requirements and siting requirements to build an ADU in the city and county of Denver these days,” Killam says. “Unfortunately, unless the costs come down, unless changes in zoning make it cheaper for construction of ADUs, I don’t see a massive movement to build these. It’s still expensive.”

Denver’s building code that restricts how a two-story ADU can be constructed means that many residents opt for larger garages in order to allow for adequate living space above, says Sarah Senderhauf, sales manager for L&D Construction.

“That’s one of the biggest things we’ve seen with the code driving up costs,” she says, “and building materials are through the roof, too.”

L&D, she adds, embraced ADUs about six years ago after the company’s owner built an ADU, with the idea that it presented a niche market. The company began putting on educational events and home tours to get the word out about ADUs, and now the structures account for about 70% of its business.

In efforts to reduce the often-prohibitive costs of ADU construction, L&D collaborated with a company called Simple Homes to create a menu of models developed specifically to specifications allowed in Denver, with off-site “panelized builds” also saving time and money. Currently, Senderhauf estimates, the company builds about 10 ADUs a year. A two- or three-car garage with living space above now runs around $340,000 — about $50,000 more than it did just a couple years ago.

“With the big zoning changes, we’re starting to see a lot more interest,” she says. “But people had this fear that all of a sudden there would be a ton of ADUs, and that’s just not the case. We’re not seeing them pop up all over, but there are more today than 2010. I think it’s going to be a gradual change.”

That tracks with what Marshall sees along his West 46th Avenue stretch of the Berkeley neighborhood. He notes that the ultimate intent of others in his group rezoning effort is a “mixed bag.” Some tell him they’d just like to have the option to build an ADU later. Others figure that it would be a plus for a buyer if they decide to sell, or that they’d rather go through the process as a group rather than jump through all the hoops themselves. And some can’t wait to get started building.

Marshall says he and his wife will move ahead with remodeling their basement into a third bedroom and bath while they wait for the zoning to go through — it could take another couple of months — before making any decisions on conversion to a full-blown ADU.

“I think my wife and I are probably the most passionate about the factors that are highlighted in Blueprint Denver,” he says. “And that’s not encouraging more sprawl. That’s better utilizing areas that were designed for higher density.”

Kevin Simpson is a co-founder of The Colorado Sun and a general assignment writer and editor. He also oversees the Sun’s literary feature, SunLit, and the site’s cartoonists. A St. Louis native and graduate of the University of Missouri’s...