IOWA CITY – In November, Iowa City adopted an update to the city’s Title 14 Zoning code to expand eligible housing types in single-family zones, adjust design and lot requirements, and provide additional regulatory incentives for affordable housing development. City staff say the amendments are a response to housing supply surveys and goals set forth by the council’s 2022 Strategic Plan.
Read our full overview of the amendments.
The amendments, which seek to “improve housing choice, increase housing supply, and encourage affordability,” were developed in consultation with many local community housing groups. Beyond these direct goals, city staff and other supporters have highlighted sustainability, walkability, and increased density as other potential benefits of the changes. While an end to the ever-destructive, exclusionary single-family zoning practice and increased flexibility for more affordable housing types is laudable, many of these amendments are ultimately impeded by other elements of the zoning code and the city’s 2013 Comprehensive Plan. The Title 14 Amendments are, in the end, a limited first step in encouraging a more urban, sustainable, and inclusive Iowa City.
Single-Family Zone Changes
A notable component of the amendments is the elimination of exclusive single-family zoning and reduction of minimum lot sizes for the city’s RS-5 and RS-8 zones, which account for the majority of the city’s neighborhoods. Duplex and attached zero-lot homes will now be allowed throughout the zones with a major caveat: ample minimum lot size rules must be met for the housing types.
| Housing Type | RS-5 Min. Lot Size | RS-8 Min. Lot Size |
| Single-Family | 6,000 sqft (7.26 du/ac) | 5,000 sqft (8.71 du/ac) |
| Duplex | 10,000 sqft (8.71 du/ac) | 8,000 sqft (10.89 du/ac) |
| Zero-Lot Line | 5,000 sqft (8.71 du/ac) | 4,000 sqft (10.89 du/ac) |
Housing density is generally expressed in units per acre (du/ac). As noted in the chart, the new lot minimums allow for a maximum density range of 7.26 du/ac to 10.89 du/ac. This is an improvement from the maximum threshold of 5.45 du/ac to 7.26 du/ac provided for prior to the amendments; however, buyers and builders are unlikely to choose to divide lots at such minimums. Further, many extant lots are below 10,000 sqft in area restricting duplex redevelopment opportunities to only larger lots. At best, marginal improvements above the 2 du/ac to 5 du/ac range neighborhoods that currently predominate the residential sectors of Iowa City are likely to be achieved.
Such marginal improvements would fall short of the immense benefits provided by housing densities above 8 du/ac. Densities above 8 du/ac are associated with a more urban character, improvements to public transit and walkability, and opportunities for neighborhood commercial amenities. Reduction of personal car trips, adoption of transit service, and mixing land uses are essential for reducing climate impacts and improving the lived experience of our cities.
Conventional planning wisdom targets this level of housing density (8+ du/ac) as a minimum rule of thumb for bus service. Iowa City’s bus service has seen great success increasing ridership with its fare-free pilot, though ridership remains below a decade ago. Long-term viability of bus service (and any potential mass transit projects) will be vastly ameliorated by increasing housing density above 8 du/ac in as many city neighborhoods as possible. Public outreach during the Iowa City Area Transit Study (2019-2020) found that the overwhelming majority of respondents desired more frequent service. Without increasing housing density to transit supportive densities, economically achieving 15-minute frequency bus service will prove elusive.
Higher housing densities not only reduce car trips through supporting better transit service, but also through creating communities conducive to neighborhood commercial services. Restaurants, corner stores, coffee shops, and small taverns that are located within a 15-minute walkshed discourage short crosstown car trips. Most residential areas of Iowa City lack such amenities. Beyond the environmental benefits, neighborhood businesses improve the lived experience of communities by serving a social role as “third places.” Indispensable to producing community ties, third places are shared spaces that one can frequently visit that is beyond their home or workplace. These spaces allow for spontaneous social interactions across all backgrounds that would not otherwise occur.
While the adopted minimum lot sizes allow for densities above 8 du/ac as an upper threshold, failing to make this density a targeted standard for Iowa City’s RS-5 and RS-8 residential zones means many of the discussed density benefits will remain out of reach. It should be noted that more radical changes to the lot size standards were likely constrained by standards established in the city’s 2013 Comprehensive Plan, which seeks a range of 2 to 8 du/ac for the RS-5 and RS-8 zones. City staff are currently preparing to begin an update of the city’s comprehensive plan that is expected to take a multi-year effort.
Single-Family Zones Looking Forward
Higher housing density should be a major priority of any update. While the current reform by the city allows for more diverse housing types within Iowa City’s neighborhoods, relatively large minimum lot sizes will continue to limit housing density. More ambitious reforms have yielded encouraging results. In 2013, the city of Houston reduced minimum lot sizes for residential zones to 3,500 square feet (12.45 du/ac) or even 1,400 sqft in special circumstances. A team of researchers from the University of Texas at Austin found that the reduced lot requirements yielded thousands of new housing units. Further, the new housing units tended to be more affordable in comparison to new construction built in other US cities. Read an overview of the study at Pew, which found similar results to an earlier project by Gray and Millsap.
Beyond minimum lot sizes, Iowa City planning staff expect the amendments to have little noticeable impact on existing neighborhoods in the short-term citing market conditions. High interest rates and construction costs make single-family to duplex conversions less attractive to potential developers. However, if a future reform were to allow more units per lot, conversions would be more financially feasible. Many zoning reforms across US cities and states have allowed townhomes, triplexes, quadplexes, or more to replace single-family lots by right including Minneapolis, Portland, and Washington state, with far more under consideration.
Despite the shortcomings of the amendments, it is commendable for a city of Iowa City’s size to adopt such reforms and be in comparison to the cities discussed above. With enough openness and ambition the city can continue tinkering towards tangibly achieving the affordability, equity, and sustainability goals set forth in the 2022 Strategic Plan.
CC-2 Commercial Zone Changes
An often overlooked change of the Title 14 Zoning amendment package adopted by the city altered the CC-2 Commercial Zone to allow multi-family use with the provision that residential units are above the ground floor. The amendments also allow ground floor residential in commercial zones if given approval through the special exception process. The change is significant as it opens most commercial areas along Highway 1, US 6, and 1st Ave to mixed-use development. However, the amendments do not alter existing requirements that inhibit urban mixed-use development such as parking requirements, floor to area ratio (FAR), and minimum lot area and open space per unit regulations. These requirements prevent compact, walkable development and increase the cost of construction by requiring more land per unit. A summary of the relevant requirements is in the table below.
| Category | CC-2 Requirement |
| Lot size per unit | 2,725 sqft (15.98 du/ac) |
| FAR | 2 |
| Open space | 10 sqft per bedroom (400 sqft min) |
| Mixed commercial parking minimum | 1 space per 250 sqft |
| Studio to 1 Bed parking minimum | 1 space per unit |
| 2 Bed to 3 Bed parking minimum | 2 spaces per unit |
Despite staff and council declaring an intent to introduce more mixed-use development with the amendments, most of Iowa City’s extant mixed-use buildings remain illegal to build in the CC-2 zone. For example, even though the 3 floor property at 1301 S Gilbert St. in the Riverfront Crossings District appears to meet the CC-2 zone’s 35ft height limit, the building contains 54 units over approximately 1.4 acres (38.57 du/ac) which is double CC-2’s allowed density of 15.98 du/ac. The property, shown below, contains ample parking and open space despite its housing density.
Traditional mixed-use buildings such as those on South Dubuque St. with ground floor storefronts and 2nd story apartments would meet the CC-2 zone’s maximum floor to area ratio, but fail the open space and parking requirements. Prior to the mid twentieth century, this style of construction dominated American commercial areas from small town mainstreets to neighborhood centers within major cities. Yet, again, this form, shown below, remains illegal in the CC-2 “Community Commercial” zone.
What could be built in CC-2?
As the previously discussed mixed-use forms remain illegal, exploring a hypothetical mixed-use development project may best aid in understanding the burden of the CC-2 zone’s additional requirements.
If a developer desired to build a 3 story project with 15 two bedroom units and ground floor commercial, they would require a one acre lot. At 900 square feet per unit, the ground floor commercial would likely be approximately 8,000 square feet. The CC-2 parking standards would require 32 spots for commercial and 30 spots for residential for a total of 62 spots. Parking lots average around 300 to 350 square feet per spot, which would give the project a range of 18,600 square feet to 21,700 square feet of lot space dedicated to parking. In other words, more than two times as much area would be used for parking than the building itself. Once the 400 square feet of open space is set aside, the lot would have between 13,460 and 16,560 square feet remaining. Though some of this area would be used for lot setback requirements, utility easements, and sidewalks, a significant amount of empty space (a third of the original acre) would go unused.
Such a development project appears unattractive both for promoting walkable urban communities and investment in redevelopment and housing construction. Parking in excess of twice the building area discourages active frontages to pedestrian environments and vastly increases the distance between buildings, while continuing to prioritize automobile access above other modes of transportation. Not only do large surface parking lots discourage walking, if many lots must leave a full third of their space undeveloped buildings will resultantly be spaced even further apart. Further, potential development will have lesser incentive to incorporate housing if the amount of land used in a project must be limited to meet housing density restrictions. Properly scaling housing density and parking requirements together with the desired mixed-use building type in mind would allow projects to better make use of their lot space; thus, making this form of housing construction more attractive.
Zoning Reform and Social Justice
Housing and land use are a social justice issue.
In his work The Color of Law, the academic Richard Rothstein documents the ways in which governments and institutions across the US directly contributed to racial segregation throughout the 20th century. According to Rothstein, in the 1920s cities began to adopt single-family zoning ordinances that prohibited the construction of apartments or businesses in zoned neighborhoods as a response to a 1917 Supreme Court decision Buchanan v. Warley which forbade racially explicit housing ordinances. Because black families were excluded from federal and private mortgage programs, single-family zones effectively segregated our cities and vastly undermined the ability for black Americans to build generational wealth.
The consequences of exclusionary single-family zones are still visible in the fabric of our cities a century later. Despite the Fair Housing Act of 1968 and many policy programs, our communities and schools remain largely segregated. A 2019 study for UC Berkeley’s Terner Center for Housing Innovation that found areas with exclusively single-family detached homes were far more likely to be predominantly white. In Iowa City, roughly 54% of black residents live in only four out of the twenty census tracts that contain the city. Four of the five census tracts with the highest proportions of white residents are filled with an overwhelming majority of owner-occupied, single-family homes. Two of these tracts, Tract 16.02 and Tract 17, include subdivisions that carried race-restricted housing covenants in the mid-20 century as identified by the University of Iowa’s Mapping Segregation project.
According to a report on racial segregation by the Othering and Belonging Institute, “The problem here lies not with single family homes, but with single-family zoning. More specifically, the problem is with zoning that prohibits multi-family homes.” While Iowa City’s adopted zoning amendments open up many single-family neighborhoods to duplexes, middle density apartments and mixed-use buildings remain illegal or difficult to build in vast sections of the city, as previously discussed for the CC-2 zone. A continued lack of choice in housing types will inhibit many residents of Iowa City from finding adequate housing near job opportunities and preferred schools furthering inequities in opportunity and freedom of movement.
Through adopting the Title 14 Zoning amendments, Iowa City City Council took a small first step in beginning to address this history. However, much work remains to be done to ensure the racial and economic integration of our city.
The Comprehensive Plan Update and Other Solutions
While the amendments passed in November expand allowable housing types and uses, as demonstrated above, housing density limits and parking minimums will continue to inhibit the production of the desired housing within Iowa City. Further reform should focus on increasing the allowable density of units and reexamining the burden of the current approach to parking minimums. Special attention needs to be given to producing the desired final forms of development sought by the 2022 Strategic Plan and Affordable Housing Action Plan.
City staff announced at a Planning & Zoning Commission meeting that an update to the 2013 Comprehensive Plan will begin this year. The plan update process will be a valuable opportunity to further the work set forth in the adopted amendments. As stated, a focus on desired end form of housing and building types rather than uses, raw density numbers, and parking formulas may yield better progress. One option for consideration would be expanding a form-based zoning citywide.
Iowa City currently employs a form-based zoning approach for the Riverfront Crossings plan area and undeveloped land within the South District and Southwest District. According to city staff, “Form-based zoning focuses less on land use (e.g. commercial v. residential) and more on the scale (e.g. bulk and height) of the development and its relationship to the street and the public realm.” The city’s existing form-based code describes standards for a variety of development types including detached homes, duplexes, row homes, small apartments, cottage apartments, and traditional mixed-use buildings. Further, the codes place less emphasis on use standards and density limits than traditional euclidean zoning. Such an approach may avoid the shortcomings discussed for mixed-use projects in the CC-2 zone and integrate more housing types into neighborhoods than the amendments allow for the extant RS-5 and RS-8 zones.
Expansion of form-based zones is already a recommended item of the 2022 Affordable Housing Action Plan and even shares support of the Northside Neighborhood Association, many of whose members voiced opposition to the adopted zoning amendments. While citywide adoption of a form-based approach would require more further action, the comprehensive plan update is an opportunity to set a foundation for future adoption. At the very least, the update should call for higher allowable housing densities in all zones discussed within this article: RS-5, RS-8, and CC-2. Doing so would alleviate barriers to the current reform effort. However, beyond city land use policies, the financial environment for funding affordable housing construction remains difficult. Other solutions should be sought to ameliorate these constraints.
Cities that have passed zoning reforms, such as Minneapolis, have found that large developers and major lenders are hesitant to build middle-density housing types due to unfamiliarity. Higher interest rates in the wake of COVID make it difficult for individual developers to take on single-family conversion projects. As seen in the Riverfront Crossing zone of Iowa City, even if large developers take on multifamily or mixed-use projects, the results are often unaffordable to most residents. Cities and states will likely need to take an active role in producing new housing, especially affordable housing.
The previously discussed report by the Othering and Belonging Institute identifies several possible interventions including rent control, land or housing trust funds, inclusionary zoning, and housing subsidies. Iowa law prohibits municipalities from enforcing rent control or mandatory inclusionary zoning ordinances. A bill to allow rent control passed an Iowa House subcommittee vote in January 2024, but has not yet been brought to the floor of either legislative chamber. Part 4 of Iowa City’s adopted zoning amendments included voluntary inclusive zoning incentives that grant density bonuses and parking reductions for affordable units. However, the city’s earlier inclusive zoning rules for the Riverfront Crossings plan have seen developers choose to pay a one-time lump sum into the city’s housing fund, rather than include affordable units in their projects.
Potential solutions to overcoming lender’s hesitation for funding missing middle and mixed-use housing types include city initiated proof-of-concept projects and public-private partnerships for loan programs. Iowa City is no stranger to direct involvement in important development opportunities. The city participated in developing the Hotel Vitro towers, the 15-story Chauncey, renovated duplexes on Taylor Drive, and is currently planning for city-owned land at 21 S Linn St. To demonstrate the feasibility of duplex conversions, ADUs, and small apartments the city could facilitate initial projects and develop a guide for private parties. Such projects could involve local lenders to establish ADU and missing middle loan programs, as done in the city of Santa Cruz, CA.
Conclusion
Though measurable impacts of the amendments will take years to come to fruition, it is clear that to achieve the city’s goals of increasing affordable housing, walkability, and sustainable development more ambitious action will be needed. Decades of exclusionary single-family zoning and the associated auto-oriented sprawl will need sustained reform and investment to overcome. We are one step closer to a more urban and inclusive Iowa City, which is no small victory nonetheless.
Stay tuned for updates about Iowa City’s upcoming 21 S Linn St redevelopment planning and Comprehensive Plan Update.