Members of the Jefferson County Council and Planning and Zoning Commission met June 11 to analyze a rough draft of the new Unified Development Order, highlighting modernized zoning districts and measurement standards, while also chewing on the pros and cons of short-term rental regulations and accessory dwelling units, like mother-in-law suites.
The joint work session between the council and commission is the first in a series of meetings organized to review the new and updated regulations laid out in the county’s Unified Development Order (UDO). The county commissioned Houseal Lavigne, a community planning consulting firm based in Chicago, to draft the new UDO.
Houseal Lavigne also worked with the county on the Visualize Jefferson County Master Plan, a 118-page document acting as the county’s official guide for land use, economic development and natural areas. The plan was approved by the council in November 2025.
County Services Director Mitch Bair said, compared to the master plan, the UDO is a more technical document used as a handbook for developers for the county’s zoning districts, building regulations and design standards.
“You’ll see throughout this conversation that there have been great efforts taken to make a very strong connection to that master plan,” Bair said. “Preserving property rights by making the rules and the processes simpler, increasing that quality, protecting adjoining property rights, and hopefully addressing many of the concerns of residents.”
County Executive Dennis Gannon ordered the joint work session between the county and the commission, Bair said, in an effort to make the UDO adoption process more collaborative. Several more joint work sessions will be held, with the next slated for August, before the UDO is taken for a vote by P and Z and the County Council.
A draft of the UDO is available on the Jefferson County website, jeffcomo.org. To view the document, go to the Agendas & Minutes tab and search for June 11 Planning and Zoning Meeting. The draft is included in the agenda packet for the meeting.
Nicole Campbell, a spokeswoman for Houseal Lavigne, said the new UDO has a consolidated and modernized list of acceptable uses for commercial zoning districts in the county, getting rid of antiquated terms and combining other terms with similar functions to create a more concise list.
“There are some uses that are maybe more traditional and don’t need to be explicitly called out,” Campbell said. “A common one we see is a haberdashery. Maybe we don’t need to be that specific, and it can be grouped into broader categories, which is what we did.”
The broader groups include retail, restaurants and personal services. The groups are defined in the UDO and include examples of what they can include. In alignment with the master plan, development standards vary in the county’s general urban, suburban and rural growth areas. For example, there may be more standards for walkability to support an active environment in the urban growth area, which includes large swaths surrounding Arnold, Kimmswick, Pevely and Festus. But in the rural growth areas, such as south of De Soto and Cedar Hill, standards might focus more on the existing character and compatibility of the area.
Also modernized are certain dimensional standards and building requirements in development applications. For example, the county’s acceptable method for measuring building height is based on roof type, which Campbell said can be complex and inconsistent. The height measurement will instead be based on average grade, which is a more common approach, Campbell said.
Review criteria are included in the UDO, so developers know exactly what is expected of them when building in the county, Campbell said. The criteria include overall alignment, ensuring traffic isn’t heavily impacted, and creating a sense of place and character.
Councilman Tim Brown (District 6, De Soto) said it may be time for the county’s requirement for a traffic impact analysis study to change. Currently, developers are expected to select a traffic consultant themselves, conduct the study and turn over their results to the county for review. Brown said the county could instead hire a traffic consultant and charge the developers to conduct a study in the area in question. Bair agreed and said a section with standards for traffic studies will likely be included in the UDO.
“In my experience, you generally get the same outcome (whether the county or a developer pays for the traffic study), but it keeps it more streamlined,” Bair said. “I think we all agree we need to refine that quite a bit. More to come on that.”
Council members and commissioners discussed certain standards and regulations they’d like to see included in the new UDO.
Councilman Charles Groeteke (District 4, Barnhart) said the county should explore drafting regulations targeting the short-term rental industry, such as Airbnb and VRBO.
Bair said the county currently does not have regulations for short-term rentals, but they could be included in the UDO. He said that since these rentals are not expressly permitted in the UDO, they are generally prohibited and should cease operations.
“If you guys want to allow (short-term rentals) and want them regulated, then we’ll put forward a draft that does that,” Bair told the council members and commissioners. “If you guys don’t want them, it’s very easy to say, ‘They’re not allowed.’ While (the rentals) are difficult to regulate and enforce when we find them, they are a lot easier to regulate and enforce when you have standards, and they don’t comply with those standards.”
The council and commission determined that they’d like to review a draft regulation along with best practices from other counties before a final decision is made on whether to allow short-term rentals.
A new design standard for the county, called accessory dwelling units (ADU), is outlined in the draft UDO. An ADU is allowed as a permanent add-on to single-family homes, either as a separate structure from the main dwelling or a structure attached to the main dwelling.
Campbell said ADUs shall not be rented for a period less than 30 days, with the intent of limiting transient guests from taking advantage of ADUs.
Under the draft UDO, ADUs would be allowed in the suburban residential, urban edge residential, neighborhood residential and mixed residential zoning districts. These districts generally allow for a higher concentration of houses in a smaller area, compared to rural residential districts.
Commissioner Chris Moenster, who represents District 7, questioned Houseal Lavigne’s thought process behind allowing the ADUs in the higher-density zoning districts, but not the lower-density districts. District 7 covers a large, rural portion of southwestern Jefferson County, including a portion of Hillsboro and Cedar Hill.
Campbell replied that the largest concern with allowing ADUs in rural areas is access to utilities, like sewer and water.
“I mean, someone who has 110 acres can’t put a mother-in-law quarters in? I’m guessing somewhere on their property is room for a second septic system,” Moenster said. “It just seems strange that we’re allowing (ADUS) all the way down to a 5,000-square-foot lot in mixed residential, but not in RR2 (rural residential) or RER22 (Rural Edge Residential). Coming at this from the side of the landowner, it just seems restrictive on the larger lots versus permissive.”
Several council members and commissioners agreed that ADUs should be allowed in larger residential lots, and Campbell said Houseal Lavigne will look into amending the section.
Both Brown and Groeteke expressed concerns with Houseal Lavigne’s minimum front yard building setbacks allowed in the smallest residential zoning districts, neighborhood residential and mixed residential. Both require homes to be built a minimum of 25 feet back from the road, and with many of today’s trucks measuring at 22-plus feet, parking in the driveways of these proposed homes may be difficult, Groeteke said.
Brown added that, under the UDO and the master plan, neighborhood sidewalks are prioritized, which could further limit the amount of off-street parking available for larger trucks.
Both Bair and Campbell said changing the setback allowances is not the proper tool for regulating driveway lengths. Rather, adequate off-street parking is addressed in the design standards portion of the UDO.
Additionally, Bair said the UDO’s design standards require a minimum amount of off-street parking spaces, and so developers must come up with alternative options, such as a rear or side entry garage, to satisfy the parking and setback requirements.