The City of Des Moines will dramatically expand homeowners' ability to construct Accessory Dwelling Units (ADUs) under an amendment to the city’s zoning code adopted by Council Monday night. ADUs are smaller homes that share a lot with a larger single-family home.
The changes allow ADUs to be built in residential areas across the city, a significant expansion over the earlier code, which only allowed them in areas already zoned for multifamily development. A press release by the City of Des Moines estimates ADUs will be allowed on 78 percent of the city's residential land following this change. In the remaining areas, other forms of multifamily housing are allowed.
Under this action by Council, ADUs would be legal to build “by right,” or with minimal city approvals, in more than half the city, including land already zoned for multifamily housing as well as areas near DART transit lines. With a conditional use permit approved by the Zoning Board of Adjustment, these homes would be allowed in other residential areas.
“We're trying to provide alternative housing options that give people different choices and provide more rooftops in Des Moines. I think that it's particularly important on our corridors and transit routes that have that extra layer of density but [need development that is] done in a way that is sensitive to the character of the neighborhood,” said Des Moines planning and urban design administrator Jason Van Essen.
Ahead of the vote, the City of Des Moines released a new resource explaining restrictions that apply to ADUs built in the city, including that they are restricted to half the size of the main house on the property and include on-site parking.
In addition, the property owner must live either in the main house or the ADU but can obtain a rental certificate for the other home on the lot if someone who is not in the homeowner's immediate family will live there. That move is intended to boost neighbors’ confidence that ADUs will not interfere with surrounding owner-occupied homes.
“An owner has to reside on the property, so you’re always going to have the actual property owner invested in what happens on that property, and I think more of the challenges that we’ve seen historically with properties that are rented is often you have the absentee landlord,” Van Essen said.
Van Essen said that while the city does not have a count of the current number of ADUs in Des Moines, they can be found in several neighborhoods. He estimated their number in the dozens, but not the hundreds, city-wide.
Local nonprofit HOME, Inc., is constructing one ADU in the Oak Park neighborhood of Des Moines. The Polk County Housing Trust Fund is tracking the construction of that home with videos on its YouTube channel.
Around the country, ADUs are known as a “gentle density” form of housing development which means neighbors may not even notice their addition on a given block. Des Moines city officials have said the expansion of ADU access aligns with changes to the city’s zoning code in 2019 and the city’s comprehensive plan, which calls for increasing housing options at various price points.
As an affordable housing strategy, one advantage of ADUs is that they do not require buying more land because they share a lot with another home. They are also an effective way of allowing smaller rental units into single-family neighborhoods where they may not otherwise be allowed, according to The ABCs of ADUs, a publication by the AARP, a national leader in advocating for ADUs across the country.
AARP also points out that ADUs are an excellent way for multiple generations of a family to live on the same property while each can keep their independence.
“It’s one thing that can be done to try to provide a variety of options for folks that are at different points in their lives,” Van Essen said. “We want to maintain our sense of place but also try to provide more housing, so I think this is a great way to do that.”
This change in zoning is the second recent policy change Des Moines has made to support more housing choices. In November, the city adjusted its development incentives to provide tax abatements for ADUs and missing middle housing – smaller multi-family developments that occupy the middle ground between single-family homes and larger apartment buildings.
Around the country, multiple changes in city codes are often necessary to spur more construction of ADUs. Van Essen acknowledged Des Moines' current actions might not be its last.
“You know zoning – it's all a living document [that’s] constantly being evaluated and changed, and so we’ll... continue to look at this and see how it goes and make changes in reaction to what we see,” he said.
Editor’s note: In the Des Moines zoning code, ADUs are referred to as Accessory Housing Units or AHUs. The two terms can be used interchangeably to describe the same type of housing.
This blog post was updated on May 10 to incorporate information from a City of Des Moines press release.
Under an updated urban renewal plan approved this week, the City of Des Moines will extend tax incentives to housing options that typically cost less for residents while incrementally adding density to neighborhoods and supporting the city’s tax base.
The plan creates a new declining tax abatement schedule for 8 years (9 years for properties with enhanced sustainability features) for “missing middle” housing that contains between 2 and 12 dwelling units. It also enhances tax incentives available for accessory housing units.
Missing middle housing describes a range of building types including smaller apartment buildings or townhouse developments that used to be common in neighborhoods but are rarer in today’s environment of large suburban single family homes and apartment complexes.
Photos: Missing middle housing can take many different formats as these examples from the Pacific Northwest show. Options range from a duplex to small apartment buildings, townhomes, and more. Images via the Sightline Institute, licensed via Creative Commons.
The more modest floor plans missing middle housing provides can make it a lower cost housing choice. The scale of missing middle housing fits nicely within predominantly single family neighborhoods, where neighbors expect new development to match the existing building style.
The tax incentives included in the City’s plan will help incentivize housing that is well-positioned to be more affordable for households with incomes under $75,000/year who are looking to buy.
This will expand housing choices for people whose wages make attaining homeownership difficult in today’s market. In fact, Des Moines cited the workforce housing study Here We Grow is based upon as part of its rationale for the new policy.
Deputy director of development services Michael Ludwig said Des Moines’ action follows years of discussion about seeking ways to add more housing that matches the style of a neighborhood.
“We know we need a greater variety of housing options and housing types in the city to have a strong housing market - a market that has a range of prices in it so that hopefully people can move up within the city without moving out,” Ludwig said.
In addition, local housing advocates like the Polk County Housing Trust Fund have long endorsed missing middle housing as an option to provide more housing at lower costs.
The plan also enhances tax incentives available to accessory housing units (AHUs) that allow homeowners to construct a second housing unit on their property. Housing choices within neighborhoods play an important role as people seek to remain in communities they love through different phases of their lives. Accessory housing units seek to address that challenge, said Brad Anderson, state director of the AARP in Iowa.
During the pandemic, he saw a spike in families interested in providing an independent living for aging loved ones adjacent to their family’s homes.
“AHUs are quickly becoming a popular affordable housing option for families who want to stay close to loved ones or provide alternative options for long-term care,” Anderson said.
AARP has prepared a resource guide for local homeowners interested in AHUs. Anderson noted that AHUs also bolster the city’s supply of more affordable housing and can be an income source for homeowners who add a rental unit to their properties.
Ludwig says for cities, supporting these new housing units also makes sense because it allows more housing value to be added in a community with less land, ultimately supporting sustainable funding for city services.
“Land is a primary cost and infrastructure is a primary cost that goes into housing affordability, and if you can get two units on a property with existing infrastructure, there are economies of scale in adding that density incrementally to an existing neighborhood,” Ludwig said.
Note: AHUs are also often called Accessory Dwelling Units or ADUs. This blog post follows the lead of the policy Des Moines passed, which uses the AHU name.
On Sept. 21, the Iowa Economic Development Authority (IEDA) awarded $29.8 million in workforce housing tax incentives to 49 projects across Iowa. Iowa’s Workforce Housing Tax Credit encourages development and rehabilitation of housing in Iowa, especially focusing on rehabilitation of vacant or underused property.
In Polk County, 6 projects were awarded a combined $3.1 million in tax credits. Those projects will support new construction of 173 new rental housing units and rehabilitation of an additional 150 rental units.
Five are located in Des Moines, while the sixth (Junction Development Catalyst, LLC) is a project in West Des Moines. Two received the maximum credit award of $1 million.
IEDA reported it received applications for nearly triple the incentives available in this funding round. The agency says projects were “scored competitively based on readiness, financing, need and local support and participation.”
Receipt of the tax credit does not require that future residents of the property will need to meet income guidelines; however, to qualify, project costs cannot exceed $200,000 (or $250,000 for historic rehabilitation) per unit.
Polk County projects funded
Number of Units
Urban Campus Apartments LLLP
Junction Development Catalyst, LLC
3524 6th Ave. Historic Rehabilitation
Source: Iowa Economic Development Authority