ADU Regulations in Iowa : The Complete Guide

Iowa is a place where small towns, open farmland, and friendly neighborhoods create a strong sense of community. With more homeowners exploring flexible housing options, Accessory Dwelling Units (ADUs) have become a growing point of interest across the state. And with Iowa developing a state-wide law permitting one ADU per lot, many cities and counties have begun developing their own clear rules to help residents add secondary housing on their property. If you’re considering building an ADU, the key is understanding how your local jurisdiction approaches zoning, size, utilities, and permitting. Zook Cabins is here to explain the essentials so you can move forward confidently.

Are ADUs Allowed in Iowa?

Yes! Under a new legislation passed in July 2025, ADUs are allowed in many parts of Iowa, but specific guidelines can vary on local zoning. Some communities, including Des Moines, Cedar Rapids, Iowa City, and Ames, have adopted or are currently finalizing ADU-specific ordinances that allow accessory units on residential lots. Other towns still restrict second units or require special approval. Before planning construction, you’ll need to confirm your zoning district and any local requirements related to placement, occupancy, or design.

What Is Considered An ADU in Iowa?

Across Iowa, an ADU is generally recognized as a self-contained dwelling located on the same lot as a single-family home. It needs to function independently, meaning it must include its own kitchen, bathroom, and sleeping area. ADUs may be attached, such as a basement apartment or converted garage or detached, like a small backyard cottage or standalone small home. The definition is the same statewide, but the rules about where and how ADUs may be built vary by city.

Can Park Model ADUs Be Used As ADUs?

This depends entirely on your local zoning and building department. Park model homes are built to RV standards rather than residential building codes. Some Iowa jurisdictions allow them in RV parks or seasonal camp settings but restrict them on residential lots unless they are converted and permitted to meet local building code standards. If you’re hoping to use a park model as an ADU, reach out to your city’s planning office before making any commitments.

Can Log Cabins Be Used As An ADU?

Yes, log cabin-style ADUs are allowed as long as they meet local building code requirements for permanent dwellings. Most Iowa cities that permit ADUs set a maximum size, often between 600 and 1,000 square feet, and require compliance with frost-depth foundations, plumbing, and insulation standards appropriate for Iowa’s climate. Several Zook Cabins designs fall comfortably within this size range, making them a practical and charming fit for a backyard ADU in Iowa.

Can Modern Cabins Be Used As An ADU?

Modern cabin designs work very well as ADUs in Iowa as long as they meet your local standards regarding height, setbacks, and foundation type. Each city establishes its own maximum size so while some allow as much as 900 square feet, others require the unit to remain smaller than the primary home. If you’re aiming for a clean, contemporary modern cabin, we can help you select a model that meets both your aesthetic preferences and your zoning requirements.

What is the Difference Between a Prefab ADU & a Modular ADU?

The distinction comes down to how the unit is transported and assembled. Prefab ADUs are built in one piece and delivered fully assembled, while modular ADUs are built in sections and finished on-site. Iowa recognizes modular homes built to residential construction standards, and many cities permit them as ADUs as long as they are placed on permanent foundations and inspected accordingly. Zook Cabins focuses on modular ADUs that meet or exceed local building and energy code requirements.

What is the Minimum Size for an Accessory Dwelling Unit?

Minimum and maximum ADU size rules vary by jurisdiction. Some Iowa cities set no minimum size beyond basic building code requirements for habitable rooms, while others specify a minimum of around 450 to 600 square feet. Maximum size limits often fall between 600 and 1,000 square feet or a percentage of the main home’s square footage. 

Can My ADU be Bigger Than My House?

No, Iowa’s state law caps ADU size at 1,000 square feet or 50% of your primary dwelling, whichever is greater. ADUs are designed to complement the primary dwelling, not overpower it. 

How Close To My House Can I Build An ADU?

Your ADU must be on the same lot as your main home, and it must comply with local setback, height, and coverage restrictions. Setback requirements differ as well, though most communities require detached ADUs to maintain standard side-yard distances and be placed behind the primary residence. Expect a typical 5 ft rear setback.

Do You Need A Permit For An ADU in Iowa?

Yes. Every ADU in Iowa requires both zoning approval and a building permit. You’ll need to confirm your lot is eligible, provide site plans showing placement and utilities, and ensure the structure meets Iowa’s residential building and energy codes. If your unit is detached or new plumbing systems are added, separate permits for electrical, mechanical, and wastewater systems may also be required. Once construction is complete, a final inspection is necessary before occupancy.

Are There Any Incentives or Grants for ADUs in Iowa?

Iowa does not currently offer a statewide ADU financial incentive. However, some municipalities and regional housing agencies periodically offer grants or low-interest financing for housing projects that expand affordable options or support aging-in-place. Availability varies, so it’s worth checking with your city housing department or regional council of governments for current programs.

Are Zook Cabin’s ADUs Built to Code?

Most definitely. With years of knowledge and experience with ADUs, our designers and builders craft each ADU with local building codes in mind, ensuring that each aspect meets and exceeds your building codes.  

Can an ADU Have Multiple Bedrooms and Bathrooms?

Yes! Why limit yourself to one bedroom when you can have two or three? Most counties and cities in Iowa limit ADUs to two bedrooms, but there may be some that permit three bedrooms. Check out our cozy and compact one bedroom options or more spacious two bedroom options for your specific needs! 

Are ADUs A Good Investment?

For many homeowners, yes. ADUs can add long-term value to a property and open the door to rental income, multi-generational living, or flexible housing for guests or caregivers. With Iowa communities increasingly discussing housing affordability and efficient land use, ADUs offer a practical, future-minded solution without requiring new land development. They are best approached as a long-term investment that supports lifestyle flexibility and property value growth over time.

What Counties in Iowa Allow ADUs?

Adair County	Adair County Supervisors
Allamakee County	Allamakee County Planning & Development
Appanoose County	Appanoose County Planning & Zoning Department
Audubon County	Audubon County Planning & Zoning Department
Benton County	Benton County Land Use Department
Black Hawk County	Black Hawk County Planning & Zoning Department
Boone County	Boone County Planning & Development Department
Bremer County	Bremer County Building, Zoning, & Environmental Health Department
Buchanan County	Buchanan County Planning & Zoning
Butler County	Butler County Zoning Department
Calhoun County	Calhoun County Zoning Department
Carroll County	Carroll County Planning & Zoning Deaprtment
Cass County	Cass County Zoning & Planning Department
Cerro Gordo County	Cerro Gordo County Planning & Zoning Department
Cherokee County	Cherokee County Zoning Department
Chickasaw County	Chickasaw County Land Use Department
Clarke County	Clarke County Zoning Department
Clay County	Clay County Zoning Department
Clayton County	Clayton County Health & Zoning Department
Clinton County	Clinton County Zoning Department
Crawford County	Crawford County Board of Supervisors
Dallas County	Dallas County Planning & Development
Davis County	Davis County Board of Supervisors
Decatur County	Decatur County Board of Supervisors
Delaware County	Delaware County Zoning
Des Moines County	Des Moines County Land Use Department
Dickinson County	Dickinson County Zoning & Environmental Health Department
Dubuque County	Dubuque County Zoning Department
Emmet County	Emmet County Iowa
Fayette County	Fayette County Planning & Zoning Department
Floyd County	Floyd County Planning & Zoning Department
Franklin County	Franklin County Zoning Department
Fremont County	Fremont County Zoning Information
Greene County	Greene County Planning & Zoning Department
Grundy County	Grundy County Zoning Department
Guthrie County	Guthrie County Planning & Zoning Department
Hancock County	Hancock County Zoning Department
Hardin County	Hardin County Planning & Zoning Department
Henry County	Henry County Planning & Zoning Department
Howard County	Howard County Board of Supervisors
Humboldt County	Humboldt County Zoning Department
Ida County	Contact Ida County
Iowa County	Iowa County Zoning Department
Jackson County	Jackson County Zoning Department
Jasper County	Jasper County Community Development Department
Jefferson County	Jefferson County Code of Ordinances
Johnson County	Johnson County Department Directory
Jones County	Jones County Land Use Department
Keokuk County	Keokuk County Board of Supervisors
Kossuth County	Kossuth County Planning & Zoning Department
Lee County	Lee County Ordinances
Linn County	Linn County Planning & Development Department
Louisa County	Louisa County Zoning Department
Lucas County	Lucas County Board of Supervisors
Lyon County	Lyon County Zoning Department
Madison County	Madison County Zoning Department
Mahaska County	Mahaska County Buildings & Maintenance
Marion County	Marion County Zoning Department
Marshall County	Marshall County Planning & Zoning
Mills County	Mills County Building & Zoning Department
Mitchell County	Mitchell County Planning & Zoning
Monona County	Monona County Environmental Health & Zoning Department
Muscatine County	Muscatine County Zoning DepartmentMuscatine County Building Department
O’Brien County	O’Brien County Board of Supervisors
Osceola County	Osceola County Zoning Department
Page County	Page County Zoning Department
Palo Alto County	Palo Alto County Zoning Department
Plymouth County	Plymouth County Zoning Department
Pocahontas County	Pocahontas County Zoning Department
Polk County	Polk County Planning & Development Department
Poweshiek County	Poweshiek County Zoning Department
Ringgold County	Ringgold County Board of Supervisors
Scott County	Scott County Planning & Development Department
Shelby County	Shelby County Planning and Zoning Department
Story County	Story County Planning & Development Department
Taylor County	Taylor County, Iowa
Union County	Union County Board of Supervisors
Van Buren County	Van Buren County Board of Supervisors
Wapello County	Wapello County Planning & Zoning Department
Warren County	Warren County Planning & Zoning Office
Washington County	Washington County Planning & Development Department
Wayne County	Wayne County Assessor
Winnebago County	Winnebago County Zoning Department
Winneshiek County	Winneshiek County Planning & Zoning Department
Woodbury County	Woodbury County Planning & Zoning Department
Worth County	Worth County Planning & Zoning Department
Wright County	Wright County Planning & Zoning Department

Does Adair County Allow ADUs? 

Yes, although there are some exceptions. In Adair County, regulations for accessory dwellings depend heavily on whether your property is inside a town boundary or in an unincorporated rural area. Most of the county is zoned agricultural, where a second dwelling on a parcel is generally allowed if it is used for family, farm workers, or long-term residential purposes and is placed on a permanent foundation. However, each incorporated town, such as Greenfield, manages its own zoning and may require a conditional use permit or limit detached accessory units. If you are looking to add an ADU in Adair County, the first step is to contact the Adair County Zoning Administrator or your city clerk to confirm your zoning district and any site-specific rules before planning your build.

Does Allamakee County Allow ADUs?

Here again, Allamakee County’s terrain and rural character mean many homeowners have space for additional structures, but the county still regulates accessory dwellings through zoning and building permits. In unincorporated areas, an ADU is usually allowed if it sits on the same parcel as the primary residence and shares utilities or water access where required. Inside cities like Waukon or Lansing, local ordinances may require the ADU to match the appearance of the main home or limit its size relative to the primary residence. Homeowners should start by reviewing their parcel’s zoning classification with the Allamakee County Zoning Office and, if inside city limits, speaking directly with the local planning department for exact ADU standards.

Does Appanoose County Allow ADUs? 

It sure does! Appanoose County allows secondary dwellings in many residential and agricultural zones, and detached ADUs typically require building permits along with verification that sewer and water systems can handle the additional unit. If your property is served by a septic system, the county sanitarian will need to evaluate capacity before approval. Anyone exploring an ADU here should begin by confirming whether their property lies inside or outside a city boundary, then contact either Appanoose County Planning and Zoning or their local city hall for permit requirements and next steps.

Does Audubon County Allow ADUs? 

Yes! In Audubon County, ADUs are most commonly approved in rural residential and agricultural zones where there is sufficient lot size and safe access for emergency services. Detached units must be placed on permanent foundations and comply with building code standards related to snow load, insulation, and structural durability. To proceed confidently, reach out to the Audubon County Zoning Office or your local city zoning administrator and request a zoning map lookup and permit guidance before you design or purchase an ADU structure.

Does Benton County Allow ADUs? 

Based on state law, yes it does! Benton County has a formal zoning framework that addresses accessory structures and occasional accessory dwellings, but the details depend on whether you are inside one of the incorporated towns like Vinton or in an unincorporated rural area. Rural parcels generally allow a second dwelling for family or long-term residential use, provided the property meets minimum lot size and septic guidelines. In town limits, ADUs may need to be smaller than the primary home and located behind or beside it rather than in front. The best starting point in Benton County is to contact the Benton County Land Use and Development Office or your local municipal planning department to confirm whether an ADU is permitted on your specific parcel and to request permit timelines.

Does Black Hawk County Allow ADUs? 

It sure does! In Black Hawk County, homeowners can add one ADU by right as long as the unit is located on the same lot as a single-family home and meets the county’s placement and building code standards. Size requirements are 1,000 feet or 50% of your primary dwelling, whichever is greatest. Many neighborhoods already have the infrastructure to support a second dwelling, which helps streamline permitting. If you’re planning an ADU here, your next step is to contact either Black Hawk County Planning and Zoning or your city’s community development office to confirm setbacks and whether your site uses public sewer or individual septic.

Does Boone County Allow ADUs? 

Per state law, Boone County now recognizes ADUs as a permitted accessory use. Because the legislation was fairly recent, there are not many specific requirements, as the county leaves it mainly up to the municipalities to decide. Inside towns like Boone and Ogden, height limits, parking requirements, and size ratios relative to the primary home often come into play. Homeowners interested in moving forward should begin with a zoning verification for their parcel, and then meet with the Boone County Building and Planning Department or their local city hall to keep the process going. 

Does Bremer County Allow ADUs? 

Yes! Bremer County allows ADUs by right, but emphasizes proper siting and access. In rural parcels outside city limits, ADUs are often easier to place as long as they maintain required distance from property lines, roadways, and agricultural activity. Inside communities such as Waverly, zoning ordinances may specify architectural compatibility or limit the ADU’s footprint to maintain neighborhood scale. Utilities are the main consideration here as public sewer hookups may require extension permits, while private septic systems must be reviewed for additional capacity. Homeowners should start by contacting the Bremer County Building and Zoning Department or their city planning office to walk through site layout expectations and the building permit process.

Does Buchanan County Allow ADUs? 

Absolutely, per Iowa law. Buchanan County supports ADUs by right, provided the unit is clearly secondary to the primary residence and adheres to established building codes. Homeowners in rural areas usually have more placement flexibility, while residents in towns like Independence may see specific guidelines for ADU height, driveway access, or exterior appearance. Because the county relies on a mix of municipal sewer and private septic, verifying your wastewater setup early will save time later. To move forward, request a zoning confirmation from Buchanan County Planning and Zoning or your local municipal planning department, then submit a preliminary site plan showing where the ADU will sit in relation to the main home.

Does Butler County Allow ADUs?

Definitely. You can build one ADU by right on a single-family lot in Butler County, subject to normal zoning and building rules. Iowa’s cap applies which states your ADU can be up to 1,000 sq ft or 50% of your primary home’s floor area, whichever is larger, and it must meet State Building Code requirements under Chapter 103A. For unincorporated parcels, expect standard setbacks from your base zoning and a utilities check and if you’re on septic, the county will look at system capacity before sign-off. Inside city limits, local rules may add design or placement standards. Start by confirming your parcel’s zoning and permit path with the Butler County Zoning Office then verify setbacks and septic or sewer details with staff before you order plans. 

Does Calhoun County Allow ADUs?

 One ADU is allowed by right on single-family lots, with the statewide size ceiling of 1,000 sq ft or 50% of the primary dwelling. In the rural unincorporated area, you’ll follow the county zoning ordinance plus State Building Code; in towns, city codes control placement and appearance. Expect the county to apply your underlying district’s setbacks and to require septic review where applicable. Pull your zoning map and confirm whether your driveway or parking layout needs adjustment; then file zoning and building permit applications together so staff can check setbacks, height, and utility connections in one pass. 

Does Carroll County Allow ADUs?

Absolutely! Carroll County recognizes one ADU by right on a single-family lot, subject to the state’s size cap (1,000 sq ft or 50% of the house) and compliance with Chapter 103A building regulations. Homeowners should start with a quick zoning verification and a sketch showing ADU footprint, distance to lot lines, and utility route. Local zoning staff will flag any adjustments before you submit for the building permit. 

Does Cass County Allow ADUs?

 Under Iowa’s ADU law, one ADU is permitted by right on any single-family lot in Cass County. Use the state maximum and plan for standard setbacks based on your zoning district. Rural sites commonly trigger septic capacity reviews while city parcels typically require proof of sewer/water availability and may apply driveway or parking criteria. Cass County’s planning staff can confirm whether your site is inside city limits and which code set applies. If you can, bring a basic site plan with dimensions and proposed utility connections to streamline your zoning and building permit review. 

Does Cerro Gordo County Allow ADUs?

 Cerro Gordo County allows one ADU by right consistent with state law, capped at 1,000 sq ft or 50% of the primary home and built to State Building Code standards. In A-1 Agricultural areas, the county historically limited dwellings per parcel but processed second units via special approvals. The new law removes the “whether allowed” question while the county still enforces siting, setbacks, access, and health department sign-off. If you’re on private septic, expect a capacity evaluation. Your first step is the Planning & Zoning portal to confirm your district and pull the permit checklist before engaging a designer.

Does Cherokee County Allow ADUs? 

Yes, you can build one ADU by right on a single-family lot in Cherokee County so long as it meets Iowa’s state standards and has full compliance with the State Building Code. The county will apply your base district’s normal setbacks and height. Note that it can’t demand extra parking, owner-occupancy, or matching exterior materials beyond what applies to a standard house. In practice, that means you’ll sketch or submit a site plan showing distances to lot lines, confirm sewer or septic capacity, and submit permits on the same timeline used for a new single-family home. Start with the county zoning office to verify your zoning map and setbacks, then move straight into building review.

Does Chickasaw County Allow ADUs?

 Chickasaw County currently has no countywide zoning ordinance, but the new state ADU law still gives you the right to add one ADU if your parcel has a single-family home. Plan to meet the statewide size cap (up to 1,000 sq ft or 50% of the main home). The county can’t add owner-occupancy, extra parking, or design-match requirements, and your permit must be processed on the same schedule as a house. Your practical next step is a call to the County Land Use office to confirm septic or utility details, then coordinate building permits with the city (if applicable).

Does Clarke County Allow ADUs?

 With ADUs now allowed by right, Clarke County homeowners can add one ADU on a single-family lot if it meets state size and building code limits. Expect your underlying zoning setbacks and height to govern placement because the county cannot require owner-occupancy, extra off-street parking matching beyond what applies to a typical house. If you’re outside city limits, you’ll go through the county’s standard building permit process and if you’re in Osceola, Murray, or Woodburn, check local rules on where a detached unit may sit on the lot. Bring a simple site plan and utility layout and keep in mind permits must be handled in the same timeframe as a single-family dwelling.

Does Clay County Allow ADUs? 

 Clay County regulates rural building through its planning and zoning process, but the state ADU law controls the headline items. One ADU by right per single-family lot, capped at 1,000 sq ft or 50% of the main home, with State Building Code compliance. The county can apply normal residential setbacks and height, yet it can’t impose added parking, require separate new utility service or force an owner-occupancy covenant. If you’re on private septic, plan for a capacity review; if you’re on city sewer/water in places like Spencer, the city utility connection standards will apply. Contact your local building department for more details on next steps. 

Does Clayton County Allow ADUs? 

 Yes, in Clayton County, you may build one ADU by right on the same lot as your single-family home if you stay within the state cap of 1,000 sq ft or 50% of the primary home. Because much of Clayton County includes river valleys and mapped floodplains, check early whether your ADU site also needs floodplain review. Prepare a site plan with lot-line distances, driveway access, and utility routing and expect that your permit should be processed on the same timeline as a single-family dwelling. 

Does Clinton County Allow ADUs?

With the new statewide allowance, a single ADU is permitted by right on any single-family lot in Clinton County, so long as the unit meets standard building and zoning requirements. Most homeowners will use the general residential zoning setbacks already in place, typically keeping the ADU behind or to the side of the main house and respecting the standard distance from property lines. Size generally follows the state allowance though cities such as Clinton or DeWitt may cap the ADU at a percentage of the main home to maintain neighborhood scale. Your first step is to call Clinton County Planning & Zoning or the city clerk’s office where your address is located to confirm setbacks and permit sequencing.

Does Crawford County Allow ADUs? 

It sure does! Crawford County recognizes one ADU by right when placed on a lot with an existing single-family home, with the same construction and safety standards required for any residential structure. In rural areas outside of communities like Denison, size is usually determined by the state guidance and available space on the parcel, with septic capacity being the key factor in approval. The county cannot require owner-occupancy covenants or special architectural matching beyond normal residential standards. Begin by confirming whether your property lies inside city limits, then request a zoning setback map and utility review before drafting your footprint.

Does Dallas County Allow ADUs? 

Yes. Dallas County is experiencing rapid suburban growth, so city-level rules play a stronger role here. The statewide by-right ADU allowance applies, meaning every single-family residential lot is eligible for one ADU, but cities like Waukee, West Des Moines (Dallas County portion), and Adel may define placement, height, and lot coverage. Size commonly lands in the 600–900 sq ft range to stay proportional to typical newer homes, though the state allows more if the primary is larger. Your best starting point is to request a zoning verification for your parcel and ask whether your neighborhood has any overlay or HOA restrictions that would affect the build.

Does Davis County Allow ADUs? 

Definitely. With the statewide by-right ADU rule in place, Davis County homeowners may add one ADU to any lot containing a single-family home, provided it meets standard setbacks and building code requirements. Davis County has large rural areas where detached ADUs are relatively simple to place as long as septic and well capacity are confirmed. Inside Bloomfield or other incorporated towns, you may see preferred placement behind the main home and basic limits on height so the ADU does not dominate street view. ADU size planning usually aligns with the state guidance of keeping the unit clearly smaller than the primary house—typically around 600–1,000 sq ft depending on the home and lot layout. Contact the County Zoning Office or the Bloomfield City Hall to get your setback distances and utility connection expectations before you draft floor plans.

Does Decatur County Allow ADUs? 

Absolutely. Decatur County falls heavily rural, which makes lot size and utilities the primary considerations rather than visual design or neighborhood compatibility. One ADU is permitted by right, but if your home uses private septic, the county sanitarian must verify the system can handle the additional bedroom count or water usage. In towns like Leon or Lamoni, the city may define how far the ADU must sit from the main house or the property line, using the same general rules applied to garages and accessory buildings. With many homes on larger parcels, detached ADUs are common, but the unit still must be built to residential code standards, not RV or park model specifications, unless converted and permitted accordingly. Homeowners should begin with a septic or utility capacity check, then request zoning setback confirmation to know exactly where the ADU can be placed.

Does Delaware County Allow ADUs? 

Yes, in Delaware County, you can add one ADU by right on a residential lot so long as the unit meets standard setbacks, height limits, and State Building Code requirements. Most parcels in the county’s smaller towns and rural areas have enough space to accommodate a detached backyard unit, but utilities determine the smoothness of the process. Inside city limits such as Manchester, expect the ADU to be placed behind or beside the main house and kept smaller to remain visually secondary—typically planned in the 600–900 sq ft range. Start by confirming your property’s zoning map and driveway access allowances with the Delaware County Planning Office before drafting your layout.

Does Des Moines County Allow ADUs?

One ADU is now permitted by right in Des Moines County, whether the parcel is inside Burlington or in the unincorporated rural area. Lots served by public sewer and water often move through the permit review more quickly, while rural parcels will need septic evaluation and verification of year-round access for emergency response. City-level zoning in Burlington may include placement guidance that keeps the ADU behind the primary house, maintaining typical neighborhood streetscapes. Height limits generally follow the same rules used for garages and accessory buildings. For most homeowners, the best first step is to obtain your parcel’s zoning classification from the county or city zoning office, then outline a simple site sketch showing building location, driveway access, and utility routing.

Does Dickinson County Allow ADUs? 

 Because Dickinson County surrounds the Iowa Great Lakes region, shoreline and drainage considerations are often as important as structure size. One ADU is allowed by right, but setbacks and impervious surface limits may affect your build, especially near West Okoboji, Spirit Lake, or Big Spirit Lake. Detached ADUs often fall in the 600–800 sq ft range here to maintain open space on lakeside lots, although the state allows up to 1,000 sq ft or 50% of the primary home if the lot layout supports it. If you are near the shoreline or in a mapped floodplain, you may need elevation or stormwater review before foundations are approved. Begin by requesting your parcel’s zoning map and shoreland overlay rules from Dickinson County Zoning, then confirm whether public sewer or private septic will support the added dwelling.

Does Dubuque County Allow ADUs? 

Yes, Dubuque County permits one ADU by right, but local standards vary depending on whether the property is in unincorporated county land or inside the City of Dubuque. The City of Dubuque has long supported smaller accessory living units, typically keeping ADUs behind the main dwelling and ensuring they remain visually secondary—often 650–900 sq ft depending on the neighborhood. In the unincorporated areas, placement is mainly controlled by standard agricultural or residential setbacks and septic capacity if sewer isn’t available. Your best next step is to ask for a zoning verification for your parcel and then request the standard building permit packet so you know the exact submittal drawings required.

Does Emmet County Allow ADUs?

Yup, Emmet County allows one ADU by right when placed on the same lot as a single-family dwelling. Rural parcels often have generous placement options, provided the unit meets side and rear setbacks and the septic system is confirmed adequate. The county cannot impose extra owner-occupancy conditions or require special parking beyond what applies to a single-family home. To begin, identify whether your parcel is served by sewer or septic, then request a zoning site plan review from Emmet County Planning so they can confirm where on the lot the ADU can be placed before you finalize building plans.

Does Fayette County Allow ADUs? 

Absolutely, in Fayette County, one ADU is permitted by right on the same lot as your primary home. Most properties in rural areas have ample room for detached ADUs, but the key approval checkpoint will be septic capacity if the property is not connected to municipal sewer. Inside communities like West Union or Oelwein, typical residential setbacks will guide placement and most homeowners position the ADU behind or to the side of the main house. Height usually follows the same limit as accessory structures such as garages, and the ADU should remain smaller and visually secondary to the primary residence. Your next step is to confirm whether your property lies inside city limits, then request zoning setback distances and utility connection guidance from the county or city planning office before finalizing your floor plan.

Does Floyd County Allow ADUs? 

Definitely! Floyd County allows one ADU by right so long as it meets State Building Code standards and the lot’s existing zoning setbacks. Rural parcels generally allow more flexibility, but private septic systems must be evaluated for additional daily flow before approval. No owner-occupancy covenant or special façade matching is required beyond standard residential rules. Start by confirming your parcel’s zoning classification and whether your utilities are municipal or private. This can be done at your local building or zoning department. 

Does Franklin County Allow ADUs? 

Yes, in Franklin County, one ADU is allowed by right on any lot with an existing single-family dwelling. The county applies its normal residential or agricultural setbacks depending on the zoning district, and the ADU must be structurally built to residential standards—not RV, camper, or park model construction unless converted to meet code. Many properties in Franklin County use private wells and septic systems, so a utilities review is commonly part of the approval process. For homeowners in towns like Hampton, municipal sewer/water simplifies permitting and placement. A practical first step is to call the Franklin County Zoning Office to verify your lot size and setback rules, then work with a builder or designer to scale the ADU below the primary home’s size for clear compliance.

Does Fremont County Allow ADUs? 

 Yes, Fremont County allows one ADU by right, but site placement depends on the underlying zoning district and available infrastructure. In rural areas where many properties sit on larger lots, detached ADUs are often straightforward to locate as long as the ADU remains smaller than the primary home and meets side and rear setback distances. If your property relies on private septic, the county sanitarian must confirm capacity or determine whether expansion is needed. Begin by confirming whether your parcel uses city utilities or septic, then request zoning setback maps and building permit timelines from the county or city planning office.

Does Greene County Allow ADUs? 

According to Iowa state law, Greene County permits one ADU by right on residential lots with a single-family dwelling. Detached ADUs are common in the county’s rural portions, provided they meet the district’s setbacks which is usually a meaningful buffer from property lines and outbuildings. In Jefferson and other municipalities, the ADU generally must be smaller than the primary home and placed behind or beside it to preserve neighborhood form. If the property connects to city sewer and water, ADU utility approvals tend to move quickly; if on septic, the county will calculate whether system capacity is adequate based on bedroom count and fixture load. Your next step is to contact the Greene County Zoning Office or the relevant city hall to confirm your zoning district and allowable build area, then produce a site plan before you submit for building permits.

Does Grundy County Allow ADUs? 

Yes, in Grundy County, a single ADU is allowed by right when placed on a lot that already has a single-family home. Most of the county includes rural parcels where space is not the limiting factor. If you are inside municipal limits, such as in Grundy Center, the ADU will generally need to be placed behind or to the side of the main home and remain noticeably smaller, commonly 600–900 sq ft depending on the size of your primary residence. The county does not impose owner-occupancy or separate parking beyond normal residential standards. Begin by confirming whether you are on city sewer or private septic, then request setback distances from the Grundy County Planning Office or your city clerk’s zoning administrator before drafting your layout.

Does Guthrie County Allow ADUs? 

Yes, Guthrie County allows one ADU by right and is largely rural, so lot size typically does not restrict the build, but placement and utilities still matter. Detached ADUs are common here and must meet standard side and rear setbacks tied to the zoning district. If your property uses a septic system, the county sanitarian must verify system capacity or specify an expansion. For homes inside Guthrie Center, Panora, or Lake Panorama communities, expect ADUs to be placed behind the main structure to maintain street-facing residential character. Size usually falls in the 500–850 sq ft range simply because of existing neighborhood scale and lot layouts, though larger is possible on bigger parcels. Start with a zoning district lookup, then contact your zoning department for more specific details. 

Does Hancock County Allow ADUs? 

 In Hancock County, one ADU can be added by right, but you must follow standard county zoning setbacks and State Building Code. No additional parking, architectural matching, or owner-occupancy requirements can be imposed beyond what applies to normal single-family construction. Your first step is to confirm whether your parcel is within city limits and request setback details, then move into the building permit review phase with a simple, scaled site plan.

Does Hardin County Allow ADUs?

Yes, Hardin County supports ADUs by right on residential parcels with an existing single-family home. If your property lies in rural unincorporated areas, expect septic or well capacity review to be the main gating factor before construction. Standard height and lot coverage rules apply, but the county cannot require additional owner-occupancy conditions or special exterior materials. Homeowners should begin by confirming whether the property uses municipal sewer or private septic, then request a setback and lot coverage verification from the Hardin County zoning office before selecting a floor plan.

Does Henry County Allow ADUs?

Based on Iowa law, in Henry County, one ADU is permitted by right, but exact placement depends on whether your property lies in a town or in unincorporated farmland. In communities like Mount Pleasant, the ADU will typically be required to sit behind the main house and remain clearly smaller, usually 600–950 sq ft to match neighborhood scale. Detached ADUs in rural areas are common, but properties on septic will undergo a sanitary review to ensure the existing system can support an additional dwelling unit. No additional parking mandates or owner-occupancy rules apply beyond standard residential requirements. To move forward, confirm your zoning district and utility service type, then prepare a basic site sketch showing setbacks and access before submitting your building permit.

Does Howard County Allow ADUs? 

 It sure does! In Howard County, one ADU is allowed by right when it is located on the same parcel as an existing single-family home. Rural parcels often have ample build space, so septic capacity becomes the primary approval checkpoint if the property isn’t connected to municipal sewer. Height and exterior finish follow standard residential building code; no owner-occupancy or special parking conditions apply beyond what is required for a normal home. Begin by verifying whether you are inside city limits, then request zoning setback distances and a septic/sewer capacity review before drafting your design.

Does Humboldt County Allow ADUs? 

Yes, Humboldt County permits one ADU by right on any single-family lot, with placement guided by the base zoning district. Detached ADUs are common on rural parcels, though the Health Department will evaluate private septic systems to ensure the added unit can be supported. In towns like Humboldt and Dakota City, the ADU is usually required to be behind the primary house to maintain a consistent street frontage.. The county cannot impose owner-occupancy requirements or special façade matching beyond standard building code. Start by requesting a zoning map lookup and a utilities check before drawing a site plan.

Does Ida County Allow ADUs?

 Yes!  One ADU is allowed by right in Ida County, and most rural properties have plenty of room for detached builds. The controlling factors are normal residential setbacks, access for emergency vehicles, and septic capacity where private systems are in use. No additional parking rules, design-matching mandates, or owner-occupancy requirements apply. Homeowners should start by confirming whether the property is covered by city sewer or private septic, then obtain permitting process steps. 

Does Iowa County Allow ADUs? 

Yes, Iowa County allows one ADU by right, with zoning setbacks and the State Building Code governing placement and construction. Large rural parcels in the county make detached ADUs practical, provided the septic system is sized appropriately or upgraded as needed. Within towns like Marengo, Williamsburg, and Millersburg, the ADU should typically be located to the rear or side of the main dwelling, and remain a secondary structure in scale. The county cannot require additional parking or owner residency restrictions beyond standard residential expectations. Contact Iowa County Planning or your city clerk’s zoning office to confirm lot coverage allowances and access requirements before designing your unit.

Does Jackson County Allow ADUs? 

Jackson County allows one ADU by right on single-family residential parcels, though terrain and slope are often important considerations due to the county’s hill country and river valleys. In rural areas, detached ADUs are typically feasible if the septic system can handle the added dwelling. Start your process by requesting a zoning setback confirmation and a utilities check, especially if your property is near a slope, drainage channel, or mapped floodplain.

Does Jasper County Allow ADUs?

Definitely. In Jasper County, one ADU may be added by right on a residential lot, as long as it meets standard setbacks and building code. In Newton and other municipalities, the ADU will typically need to be placed behind or beside the primary home to preserve the neighborhood’s front-facing appearance. If the property uses private septic, the county sanitarian will confirm system capacity before approval. Start by requesting a zoning map lookup and setback verification, then proceed to a building permit application with a simple site plan.

Does Jefferson County Allow ADUs? 

 Jefferson County permits a single ADU on a residential parcel without the need for a special use hearing. Rural parcels have more placement flexibility, but septic and well capacity must be confirmed prior to building permit approval. No owner-occupancy covenant or special architectural matching is required beyond normal residential building standards. Begin by confirming whether the property is inside a city boundary, then request setback distances and a sewer or septic connection review before finalizing design.

Does Johnson County Allow ADUs? 

In Johnson County, the growth around Iowa City means city-level zoning plays a strong role. One ADU is allowed by right, but in neighborhoods served by municipal sewer and water, the ADU is typically required to remain behind or offset from the primary home. Many ADUs in Iowa City and Coralville fall in the 550–900 square foot range due to established lot sizes and block layouts. Detached ADUs are permitted, but the new structure must still meet residential foundation, insulation, and life-safety code requirements. In rural Johnson County, septic capacity will determine whether the ADU can include multiple bedrooms or a full kitchen. The best starting step is to request your parcel’s zoning and utility service type from the planning office, then create a site plan showing placement and access.

Does Jones County Allow ADUs? 

Yes, Jones County allows one ADU by right on lots with an existing single-family home. Rural properties often have enough space to accommodate a detached ADU, but all units must comply with the same building code standards as a house, including frost-depth foundation and compliant plumbing and electrical systems. The county cannot require additional parking or enforce a separate owner-occupancy rule beyond what applies to normal residential use. Begin by confirming the zoning district and whether your property uses public sewer or septic, then obtain a simple site sketch for permit review.

Does Keokuk County Allow ADUs? 

Yes! Keokuk County allows one ADU by right on a single-family lot and primarily evaluates projects based on setbacks, utility service, and compliance with residential building standards. Many properties are on private wells and septic systems, so confirming septic capacity is often the first step if the ADU will be a full living space. In towns like Sigourney, the ADU is generally positioned behind the existing home, maintaining the established street pattern. Size is usually kept modest, often in the 500–850 square foot range, though larger lots can support more as long as the ADU is clearly secondary to the main dwelling. Request a zoning and utility check from the county or city clerk, then move forward with a building permit submittal that includes a scaled site plan.

Does Kossuth County Allow ADUs? 

It sure does! In Kossuth County, one ADU can be added by right to any single-family lot. Most rural properties in this county have the space for a detached ADU, so the primary considerations are setback distance from property lines and whether the existing septic system can support the additional unit. In towns like Algona or Bancroft, the ADU will typically need to sit behind or beside the primary home, and remain secondary in size—usually 600–950 square feet depending on the main dwelling. There are no special design-match or owner-occupancy requirements beyond standard residential construction code. Homeowners should begin by verifying zoning classification and utility type, then create a simple site layout showing placement and access before submitting building permits.

Does Lee County Allow ADUs? 

Yes, Lee County allows one ADU by right on lots containing a single-family residence. For rural parcels, ADU feasibility hinges mostly on septic and well capacity. No additional parking or owner-occupancy mandates are added specifically for ADUs. Start by verifying whether your home is connected to municipal utilities; then request setback and site plan review guidance from the local planning office.

Does Linn County Allow ADUs? 

Yes, Linn County does allow one ADU by right; however, properties inside the City of Cedar Rapids follow municipal standards that are more specific about ADU placement. In Cedar Rapids and Marion, ADUs are typically required to be located behind the front face of the main house to maintain the neighborhood’s visual pattern. Rural Linn County parcels frequently use septic, so a capacity evaluation is necessary if adding a full kitchen and bathroom. Start by confirming whether your parcel is in an incorporated city or in unincorporated county land, then request zoning setbacks and utility review before design planning.

Does Louisa County Allow ADUs? 

Yes, In Louisa County, one ADU is allowed by right on a single-family lot and must comply with the same State Building Code as the primary residence. Many homes in the county’s rural areas rely on septic and well systems, so the health department review is usually the most critical approval step. In towns like Wapello or Columbus Junction, the ADU will typically be placed behind the main dwelling and kept clearly smaller—commonly 500–850 square feet depending on lot depth. Standard side and rear setbacks apply. No special parking, owner-occupancy, or architectural matching rules are applied beyond normal residential requirements. Homeowners should start by confirming their utility setup and obtaining a zoning setback map before drafting their building layout.

Does Lucas County Allow ADUs? 

Yes! Lucas County allows one ADU by right so long as the structure meets residential code and zoning placement rules. In rural areas, detached ADUs are common as long as septic system capacity can be verified or expanded if needed. Within Chariton and other incorporated towns, placement generally requires the ADU to remain to the rear or side of the primary house. The county cannot impose additional parking, owner-occupancy, or aesthetic mandates specific to ADUs. A good starting point is to confirm your parcel’s zoning district and request a site plan review appointment so setbacks and access can be confirmed before the design phase.

Does Lyon County Allow ADUs? 

Yes, in Lyon County, one ADU is permitted by right when located on the same lot as an existing single-family home. Many properties here are rural and already have available yard space, so the main approval factor is septic capacity if the property is not on municipal sewer. Standard setbacks apply based on the zoning district. Start by confirming whether your parcel is on city utilities or private septic, then request a setback verification before designing foundation placement and utility routing.

Does Madison County Allow ADUs? 

Madison County allows one ADU by right on residential parcels. Many homes in rural areas can accommodate a detached ADU easily, but the county will require a health department review of your septic system if you are not connected to public sewer. In Winterset and other municipalities, ADUs must typically sit to the rear of the main structure to maintain traditional street-facing home profiles. No special parking mandates or owner-occupancy covenants apply. Start with a zoning map check and utility confirmation, then prepare a simple site plan before submitting your building permit application.

Does Mahaska County Allow ADUs? 

Yes, in Mahaska County, one ADU is allowed by right on a residential lot, with placement governed by standard zoning setbacks and State Building Code. In rural areas, detached ADUs are common as long as the septic system is rated to handle the additional dwelling or can be expanded. Begin by requesting a zoning verification from the county or city, then determine whether your property is served by public sewer or requires septic capacity review before drafting building plans.

Does Marion County Allow ADUs? 

Yes, Marion County permits one ADU by right for single-family lots. Rural parcels have greater flexibility, but private septic capacity is the determining factor for full-use ADUs with kitchens and bathrooms. No additional owner-occupancy or parking rules are applied beyond standard residential code. Homeowners should request a zoning setback map and utility review early, as this will define the workable building envelope before design.

Does Marshall County Allow ADUs? 

Yes, Marshall County allows one ADU by right and evaluates projects primarily based on existing zoning setbacks and utility availability. For properties inside Marshalltown, the ADU is usually required to sit behind or offset from the primary structure to maintain residential frontage patterns. Start by verifying your zoning district, then create a basic site diagram showing structure placement, driveway access, and utility routing before initiating building permitting.

Does Mills County Allow ADUs? 

Yes, new laws now require Mills County to allow one ADU by right on a single-family lot, but lot layout and utilities determine how the ADU can be placed.Typical ADU sizes fall between 600–950 square feet, though larger may be possible if the primary home is large enough and setbacks allow. In rural areas, septic capacity is the key approval factor; the county sanitarian will verify whether the existing system can support the ADU’s kitchen and bathroom load. Begin by confirming whether your property is inside city limits, then request zoning setback distances and a utilities review before designing your building footprint.

Does Mitchell County Allow ADUs? 

It sure does. In Mitchell County, one ADU is permitted by right, with placement regulated by standard setbacks for your zoning district. If your property is not connected to municipal sewer, a septic evaluation will be required to determine whether expansion or modification is needed. Height limits follow normal residential accessory structure guidelines. The county does not add owner-occupancy rules or force architectural matching beyond standard building code. Start by confirming zoning classification and utility type, then start the permit process through the local building department. 

Does Monona County Allow ADUs? 

Yes, Monona County permits one ADU by right with the same building and safety standards required for a primary dwelling. Normal side and rear setbacks apply, and the ADU must sit on a permanent foundation. No additional parking or owner-occupancy conditions are imposed. Homeowners should start with a zoning map check and septic/sewer utility review before developing final layout drawings.

Does Muscatine County Allow ADUs? 

Yes, Muscatine County allows one ADU by right when placed on the same lot as a single-family dwelling. Properties inside Muscatine city limits often have more defined placement expectations, requiring the ADU to be behind the main home to maintain neighborhood character. In unincorporated rural areas, the county will focus on septic capacity and safe driveway access rather than architectural matching or parking. Start your process by determining whether your parcel is on city sewer or private septic, then request a zoning setback diagram so you know where the ADU can be positioned without adjustment.

Does O’Brien County Allow ADUs? 

Yes, O’Brien County permits a single ADU by right on residential parcels. In rural zones, detached ADUs are common, but the feasibility is tied to whether your septic system can handle the additional load. Height and exterior finish follow the same rules applied to ordinary residential structures with no additional owner-occupancy or parking requirements apply. A smart first step is to confirm zoning and utilities, then prepare a simple site plan marking distances to property lines, the main house, and utility tie-in points before applying for permits.

Does Osceola County Allow ADUs? 

 Because of new Iowa law, Osceola County allows one ADU by right on a single-family lot, with the structure required to meet standard residential construction code. In the county’s rural areas, detached ADUs are common due to larger lot sizes, but the septic system must be evaluated to ensure it can handle the added use. Standard accessory building setbacks apply. The first step is confirming whether your home is on municipal sewer or private septic, then requesting a zoning setback verification from the county or city zoning office.

Does Page County Allow ADUs? 

Yes, In Page County, one ADU is allowed by right, and the county relies on its standard setbacks and building code to guide placement. Rural properties often already have sufficient space for detached backyard cottages, but septic capacity must be confirmed if not on city sewer.To begin, verify your zoning district and utility setup, then prepare a basic site plan showing building location, driveway, and utility tie-ins before applying for permits.

Does Palo Alto County Allow ADUs? 

Yes, Palo Alto County permits one ADU by right on residential lots with an existing single-family dwelling. In rural settings, detached ADUs are often straightforward as long as there is septic capacity and access for emergency vehicles. In towns like Emmetsburg, the ADU should generally be located to the rear or side of the main home and sized to maintain a secondary role.  Standard setbacks and height limits apply. The county does not add extra parking or owner-occupancy rules. Homeowners should start with a zoning map lookup and a utilities check before designing foundation placement and service routing.

Does Plymouth County Allow ADUs? 

Definitely.  In Plymouth County, one ADU is allowed by right, with placement determined by base zoning setbacks and the lot’s available build area. Detached ADUs are common on rural parcels, but the county will require a health department review if the property is on a private septic system. The ADU must be built to full residential code standards, including frost-depth footings, insulation, and life safety systems. Start by confirming zoning and utility service, then prepare a simple site sketch for permitting.

Does Pocahontas County Allow ADUs? 

Yes, Pocahontas County permits one ADU by right on lots with a single-family home. The county’s rural land base means space is not usually the issue; instead, feasibility depends on septic capacity and proper placement within required property line setbacks.. A good first step is to request a zoning setback check and utility evaluation before drafting building plans.

Does Polk County Allow ADUs? 

 Polk County allows one ADU by right on any single-family residential lot. In unincorporated Polk County, the ADU must meet standard residential setbacks and be structurally built to the same code as the primary home. Properties connected to city sewer/water typically move through permitting faster, while rural parcels require septic capacity verification before approval. Start by confirming whether your address is in city limits (because that determines which office handles your permit), then request a setback and lot coverage check before finalizing your floor plan.

Does Poweshiek County Allow ADUs? 

Yes, Poweshiek County permits one ADU by right on single-family lots, with feasibility determined mainly by utilities and setback room. No special design matching, parking, or owner-occupancy rules apply beyond standard residential construction. Standard Iowa laws regarding ADUs apply to this county. Your next step is to confirm whether your property is on city sewer or private septic, then request a zoning setback verification to determine your buildable footprint.

Does Ringgold County Allow ADUs? 

In Ringgold County, one ADU is allowed by right, and the county mainly applies its standard accessory building setbacks and building code requirements. Most residential parcels here are larger or semi-rural, so detached ADUs are common. The determining factor is typically septic capacity if the property is outside city sewer service. In towns like Mount Ayr, the ADU should remain secondary in scale, usually 550–900 sq ft, and kept to the rear of the main house to maintain visual consistency along the street. No owner-occupancy or additional parking requirements are added. Begin with a zoning and utilities confirmation, then prepare a sketch showing distances to lot lines and access points before applying for permits.

Does Scott County Allow ADUs? 

Scott County allows one ADU by right, but because it includes major municipalities such as Davenport and Bettendorf, city-level requirements define placement more specifically. In urban areas, ADUs are generally required to be located behind the main home and remain clearly smaller hough larger lots can support larger footprints. Height usually must remain below or at the secondary accessory structure limit to maintain neighborhood scale. In unincorporated rural parts of Scott County, septic capacity drives feasibility. At the start of planning, request a parcel zoning lookup to determine whether your permit will be processed through the city or the county, then confirm permit steps. 

Does Shelby County Allow ADUs? 

Definitely. Shelby County permits one ADU by right alongside a single-family residence. Rural parcels typically have space to accommodate detached ADUs, but like most Iowa counties, the septic system must be confirmed capable of supporting the added dwelling. Height limits and materials follow standard residential building rules. No special parking or owner-occupancy requirements apply. Start with zoning verification and a utility service review, then prepare a simple site plan before submitting for permits.

Does Story County Allow ADUs? 

Yes, Story County allows one ADU by right when placed on a lot with a single-family residence. Because the county includes Ames, placement and size standards can vary by location. In Ames neighborhoods, the ADU must generally sit behind the main home and remain clearly secondary. In the unincorporated rural areas, there is usually ample placement flexibility, but septic capacity is the primary approval step if the home is not on municipal sewer. No additional parking or owner-occupancy covenants are imposed beyond standard dwelling rules. Begin by confirming whether your property lies inside Ames city jurisdiction or unincorporated county, then request a meeting with your local zoning department to discuss next steps. 

Does Taylor County Allow ADUs? 

Yes, Taylor County permits one ADU by right on residential parcels. Most properties here are rural, so space is generally not the limiting factor. Instead, you will need to verify septic system capacity if the property is not served by city sewer. Standard residential setbacks apply, and the ADU must be built on a permanent foundation. No extra owner-occupancy or design-match requirements are added. Start with a zoning district lookup and a connection with your local building department. 

Does Union County Allow ADUs? 

Yes, Union County allows one ADU by right on a single-family lot. In Creston and other incorporated communities, the ADU should be set to the rear of the main house and remain visually secondary, with common sizes falling in the 600–950 sq ft range. In rural areas, detached ADUs are straightforward as long as property line setbacks are met and the septic system can support the additional wastewater load. Structural code standards for frost-depth foundation, plumbing, and electrical still apply just like with any home. To start, confirm zoning classification and utilities, then sketch a site plan showing placement, driveway access, and utility routing before submitting for permits.

Does Van Buren County Allow ADUs? 

Van Buren County allows one ADU by right and relies on standard residential zoning rules to determine placement. No additional parking, architectural matching, or owner-occupancy rules apply beyond the norms for a standard dwelling. Your best first move is to confirm whether the property is inside or outside city limits, then request setback verification. Your local zoning and building departments are critical to this process. 

Does Wapello County Allow ADUs? 

Absolutely. Wapello County allows one ADU by right with typical zoning setbacks and State Building Code compliance. In Ottumwa, ADUs are generally expected to be sited behind the main house to maintain consistent street frontage. ADUs here usually fall in the 600–950 sq ft range to match existing lot patterns, though larger may be allowed on deep lots as long as the structure is clearly secondary. In rural parts of the county, feasibility hinges on septic and well capacity, and an evaluation may be required before construction approval. No additional parking mandates or owner-occupancy clauses are added. Start by contacting your local zoning department to get the ball rolling. 

Does Warren County Allow ADUs? 

Because of new legislation, Warren County allows one ADU by right on any lot with an existing single-family residence. In rural parts of Warren County, feasibility hinges on septic capacity, which must be verified before the county issues building approval. The simplest path is to determine whether your parcel is inside city limits or under county jurisdiction, then request a setback and utility confirmation before drafting your building layout.

Does Washington County Allow ADUs? 

Yes, Washington County permits one ADU by right, with placement determined by standard residential setbacks and lot coverage limits. In Washington and Kalona, ADUs typically must sit to the rear or side of the primary home and stay smaller  depending on the typical neighborhood scale. Rural parcels often allow more placement flexibility, but septic and private well systems need capacity review before permitting. The ADU must sit on a permanent foundation and meet insulation and life-safety code requirements just like a main home. Your best first step is to request zoning and utility verification from the county or city planning office, then obtain the building plans. 

Does Wayne County Allow ADUs? 

Wayne County allows one ADU by right for single-family properties, with most approvals hinging on utility capacity and proper setbacks. Many parcels here are rural, so detached ADUs are usually feasible as long as the septic system can support the additional dwelling. According to Iowa law, the ADU must meet the same structural and energy code standards as the primary home, including frost-depth foundation and proper egress. Start your process by confirming whether the property is sewered or on septic, then request setback distances before designing the building footprint.

Does Winnebago County Allow ADUs? 

Yes, Winnebago County permits one ADU by right when located on the same parcel as a single-family home. Rural lots here often have space for a detached ADU, but septic capacity review is required if not connected to municipal sewer. The county does not impose additional owner-occupancy or parking requirements for ADUs. Begin by verifying your zoning district, then go to your local zoning or building department to ask about the next step. 

Does Winneshiek County Allow ADUs? 

Winneshiek County allows one ADU by right, but planning depends on whether the property lies in the rural county or inside cities such as Decorah. In Decorah, ADUs are usually expected to be placed behind the primary structure and sized to maintain a secondary role. Rural parcels often have more flexibility, but well and septic capacity review is standard before approval. All ADUs must comply with the State Building Code for structural safety, energy performance, and long-term residential use. The best starting point is to request a zoning and utility assessment, then shape your design to fit the workable building envelope identified during the site review.

Does Woodbury County Allow ADUs? 

Yes, Woodbury County allows one ADU by right on a single-family residential lot. In unincorporated rural areas, detached ADUs are common and usually straightforward to position as long as the septic system is evaluated and rated for the additional living space. Within Sioux City, placement typically requires the ADU to sit behind or to the side of the primary home, maintaining a consistent street-facing profile. Begin your process by confirming whether your address falls under city review or county review, then request a setback and utility confirmation before finalizing design.

Does Worth County Allow ADUs? 

Yes, Worth County permits one ADU by right on single-family parcels, but placement depends on both setbacks and whether the property uses municipal sewer or private septic. In rural areas, there is typically ample build space and the primary check will be verifying septic capacity or planning a system expansion if needed. In communities like Northwood and Manly, ADUs are generally expected to be located behind the main residence and remain secondary in size. No additional parking or owner-occupancy restrictions apply beyond standard residential code. A practical starting step is to request zoning district and setback guidance, then prepare a simple site layout showing building placement and access.

Does Wright County Allow ADUs? 

Definitely! Wright County allows one ADU by right when placed on the same lot as a single-family home. Detached ADUs are commonly feasible in rural parts of the county, provided the septic system is approved for the additional wastewater load. All ADUs must meet State Building Code requirements, including frost-depth foundations, safe egress, insulation, and proper electrical and plumbing installation. Start by confirming whether your parcel is served by city utilities or private systems, then request a zoning setback map to establish your buildable area before drafting house plans. 

Accessory Dwelling Unit Requirements by Municipalities 

Des Moines	Des Moines Development Services
Cedar Rapids	Cedar Rapids Development Services
Davenport	Davenport Building & Land Development Services
Sioux City	Sioux City Planning & Zoning Division
Iowa City	Iowa City Development Services
Ankeny	Ankeny Licenses and Permits
Dubuque	Dubuque Planning & Zoning Department
Urbandale	Urbandale Community Development Department
Marion	Marion Zoning Department
Waterloo	Waterloo Planning & Zoning Department
Ames	Ames Planning Department
Cedar Falls	Cedar Falls Community Development Services
Council Bluffs	Council Bluffs Community Development Department
Bettendorf	Bettendorf Community Development Department
Waukee	Waukee Community Development Department

Does Des Moines, Iowa, Allow ADUs? 

Yes, like other Iowan cities, Des Moines allows ADUs up to 1,000 square feet or half your primary dwelling’s size, whichever is larger. Regulations on setbacks and permitting process can be obtained by contacting the Plan and Zoning Commission. They will direct you to take the next step.

 

Does Cedar Rapids, Iowa, Allow ADUs? 

Yes! Cedar Rapids allows ADUs. The city defines an ADU as a fully self-contained unit with its own kitchen, bath, sleeping area, located on the same lot as the main house. The key rules for ADUs are one ADU per lot and compliance with building codes. Homeowners should contact the Planning & Zoning Division or email zoning@cedar-rapids.org to get the ADU checklist packet and confirm current setbacks/design rules.

Does Davenport, Iowa, Allow ADUs? 

It sure does. Davenport allows accessory dwelling units as defined in its zoning code. Important homeowner requirements to note is that only one ADU per lot is allowed. That ADU must include separate cooking and sanitary facilities and independent exits from the primary dwelling. If detached, the ADU must be located in the rear yard and meet the setback and height rules that apply to detached garages. The next step is to review the city’s zoning code and contact Davenport’s Community Development department to pull any accessory-dwelling permit forms and confirm lot-specific setback/height/utility rules.

Does Sioux City, Iowa, Allow ADUs? 

Absolutely! The city’s Zoning & Sign Code includes provisions for “Accessory Dwelling Units” and identifies two types attached or detached. The rules still require compliance with all accessory-structure setback, height and yard requirements. For homeowners, you will want to  check the city’s official Zoning & Sign Code available online, and then meet with the Planning Division of Sioux City (712-224-5500) to go through other details like setbacks, utilities, building code compliance, and permit process.

Does Iowa City, Iowa, Allow ADUs? 

Yes, Iowa City allows ADUs. According to the city’s planning site, ADUs can be built on any property with a single-family or duplex home in any residential zone and owner-occupancy is required. Additionally, the ADU must be accessory to the principal dwelling and size is limited to the larger of 1,000 sq ft or 50% of the main building’s floor area. Visit Iowa City’s Neighborhood & Development Services to download the ADU requirements and submit the building permit through the city’s Development Services.

Does Ankeny, Iowa, Allow ADUs? 

At present there’s no clearly defined ADU-specific ordinance publicly stated because the municipal code focuses on accessory buildings (garages, sheds) with limits. However, because the state law permits one ADU per lot in Iowan cities, it is very likely Ankeny also allows them. If you’re a homeowner in Ankeny considering an ADU, you’ll want to contact the Planning & Zoning at the City of Ankeny to ask if an ADU is allowed under current zoning, and what permit process applies. 

Does Dubuque, Iowa, Allow ADUs? 

Yes, although specific regulations are not clear. You can always rely on the statewide mandate for one ADU per lot but because this city does not offer specific size limitations or have legislation yet regarding ADUs, you will need to contact Dubuque’s Planning & Zoning to find out all the correct information. 

Does Urbandale, Iowa, Allow ADUs? 

Yes! Urbandale explicitly includes a section titled “Accessory Dwelling Unit” in its code. Key homeowner requirements to be aware of are as follows: no more than one ADU per eligible property, size cap is either 1,000 sq ft or 50% of primary dwelling (whichever greater), a maximum of two bedrooms.So if you’re in Urbandale, contact the Zoning Division, download the ADU handout, and review parking, utility, setback and occupancy rules before submitting your permit application.

Does Marion, Iowa, Allow ADUs? 

It sure does. The city’s code includes “Auxiliary Dwelling Unit” language in the specific use standards which suggests that a secondary dwelling unit is permitted under defined conditions. For a homeowner you will need to look at Marion’s “Auxiliary Dwelling Unit” section then call Marion’s Community Development and ask for the application form and guidance on ADU compliance and zoning district eligibility.

Does Waterloo, Iowa, Allow ADUs? 

Yes, although local zoning codes don’t reference the specifics yet. Waterloo’s zoning and building regulations primarily reference accessory structures in general ( but we did not locate a clear, dedicated “ADU” section in the publicly cited code. As a homeowner in Waterloo, if you’re thinking about an ADU, you should contact the Building Inspections and Planning Departments, ask whether the zoning code permits self-contained accessory dwellings, and check standards on parking, utilities, setbacks, and whether separate kitchen/bath facilities are allowed.

Does Ames, Iowa, Allow ADUs? 

Yes! Ames allows accessory dwelling units. The city’s ordinance defines an ADU as a detached or attached residential unit on the same lot as a single-family residence. Key rules for homeowners is that the unit is capped at 900 square feet, limited to one bedroom, and the property owner must live in either the main home or the ADU. One parking space is required in addition to existing parking. Visit the City of Ames “ADUs & Duplexes” page, download their ADU brochure/checklist, and schedule a meeting with the Planning Division to review lot‐specific zoning and permit requirements.

Does Cedar Falls, Iowa, Allow ADUs? 

It sure does! Cedar Falls’s zoning code includes a definition for “Accessory dwelling unit” as “a small secondary dwelling unit that is accessory to a detached single-unit dwelling. While there are not more specific limits on size and setbacks, the presence of the definition means the city recognizes ADUs. Homeowners should approach the Planning & Community Services Division and request the latest ADU policy in Cedar Falls. 

Does Council Bluffs, Iowa, Allow ADUs? 

Yes, under state law, but local regulations are unclear at this point.  This means you will need to directly contact Council Bluffs’ Community Development and ask directly if the city accepts applications for accessory dwelling units (with separate kitchen/bath) on single-family lots and what the design, setback, and building‐code standards are for such units.

Does Bettendorf, Iowa, Allow ADUs? 

Absolutely! Bettendorf specifically permits ADUs in its zoning regulations under “Accessory Dwelling Units. ADUs are permitted in single-family homes and are subject to the following additional requirements. Only one ADU is permitted per lot and the ADU must meet all building and city code requirements. Additionally, approval is by special-use permit. The next step is to reach out to Bettendorf’s Community Development, request the ADU application form, review the special-use permit criteria, and get other relevant information. 

Does Waukee, Iowa, Allow ADUs? 

It is likely, but not definitively detailed because while Waukee’s zoning and accessory structure code has strong language around accessory buildings like sheds and garages, there are not specifics about ADUs. Given the state law requiring cities to permit ADUs, Waukee must allow them in some form. Your next best step is to contact Waukee’s Planning & Zoning Department and obtain the current policy/permit requirements, especially focusing on whether detached units are allowed, and what standards apply. 

Searching for an ADU Builder Serving Iowa? 

The best part about learning the regulations is that you are now ready for the next phase: finding an ADU builder you can trust. Zook Cabins reaches you in Iowa, no matter where you live! Combining decades of experience with ADUs plus a passion for non-traditional living makes our team the perfect fit for you. Interested in learning more? Simply contact us and talk to a sales representative or request a free quote to be one step closer to owning a luxurious ADU. We guarantee you up front pricing, quality commitment, and the support you need through the whole process. 

Tiny Homes & ADU Rules by State: How Do They Compare?

Quite honestly, regulations around tiny homes and ADUs can be overwhelming and discouraging. Luckily, Zook Cabins is here to cut through the confusion and provide clarity for you. Curious to know which states allow tiny homes but not ADUs, or vice versa? Or are you interested in a certain county for both? We provide the answers you need with our tiny home regulations articles and our ADU regulations, each by individual state. Simply click on the state you want to learn more about and you’re on your way to clarity! No matter where you live, Zook Cabins wants to make it possible for you to embrace a new way of living.

Conclusion…

As you can see, Iowa is like many of the other states. Some areas are great for ADUs, while other areas still need to catch up with the times. At Zook Cabins, we strive to help you find the perfect ADU to fit your needs. So when you are ready to start the process of adding an ADU to your property, contact us. We would love to help you Dwell Beyond The Ordinary.