ADU Rules in Des Moines, IA (2026)
ADU rules, permit requirements, size limits, and fees for Des Moines, IA. Source-cited from official municipal code.
Yes, ADUs are allowed in Des Moines, IA.
Des Moines, IA permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Des Moines, the Des Moines Permit and Development Center handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Des Moines.
ADU Size Limits
ADU Size Limits in Des Moines: Detached ADU: up to 900 sq ft (max height: 24 feet). Attached ADU: 700 sq ft. Des Moines ADU regulations under Chapter 134. Detached ADU (carriage house, garage apartment) limited to approximately 900 sqft. JADU is a California-specific concept not applicable in Iowa. Des Moines's affordable land market makes ADU construction more economically viable than in coastal cities.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 900 sq ft | 24 feet |
| Attached ADU | 700 sq ft | Per primary structure zone height |
Permit Fees
ADU Permit Fees in Des Moines: Plan check fee: $100-$500. Building permit fee: Based on construction value — typically $700-$3,000. Impact fees: None. School fees: None or N/A. Total estimated permit cost: $800-$3,500 total permit fees. Des Moines Permit Center fee schedule. No development impact fees. Des Moines's permitting costs are among the most affordable of any major US city. Source: dsm.city/departments/permit_and_development_center-division
| Fee Type | Amount |
|---|---|
| Plan Check | $100-$500 |
| Building Permit | Based on construction value — typically $700-$3,000 |
| Impact Fees | None |
| School Fees | None |
| Total Estimate | $800-$3,500 total permit fees |
Permit Timeline
Des Moines ADU Permit Timeline: Des Moines Permit and Development Center: ADU permits typically 3-6 weeks for plan review. Construction 2-7 months. Des Moines has a streamlined online permit portal. Apply through the Des Moines Permit and Development Center online permit portal. Phone: (515) 283-4200.
Setback Requirements
ADU Setback Requirements in Des Moines: Front setback: follows zone standard. Side setback: 3 feet. Rear setback: 5 feet. Des Moines rear yard setback for accessory structures is typically 5 ft from rear property line, 3 ft from side property line. Des Moines standard lot sizes vary by zone — R1-60 requires 6,000 sqft minimum, R1-80 requires 8,000 sqft. Per Des Moines Zoning Ordinance Chapter 134.
Parking Requirements
Parking Requirements: One parking space required per ADU. Des Moines's auto-dependent urban form means most parcels can accommodate on-site parking. Reduced parking requirements may apply in transit-corridor overlay zones near ART (Arterial Rapid Transit) routes.
Restrictions & Requirements
- ADU must comply with Des Moines Building Code habitability standards
- Detached ADU located in rear yard behind principal structure
- Must maintain zone setback requirements
- Sherman Hill Historic District and other historic overlays require HDC review
- Flood plain overlay along Des Moines River and Raccoon River corridors restricts construction
- Iowa tornado country — construction must meet wind-load and storm shelter requirements
How Many ADUs Are Allowed?
Number of ADUs Allowed in Des Moines: Single-family lots: 1 ADU per lot. Multifamily properties: Accessory units on multifamily parcels subject to site plan review. Des Moines's affordable land costs and relatively low construction costs compared to coastal cities make ADU projects economically attractive for property investors. The city has been exploring incentives for ADU development to address housing affordability.
Single-Family Lots
1 ADU per lot
Multifamily Properties
Accessory units on multifamily parcels subject to site plan review
Historic District Considerations
Historic District Requirements: Des Moines has 5 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Des Moines Historic Preservation Commission administers local historic landmarks and districts. Sherman Hill Historic District is the most prominent — a Victorian neighborhood immediately west of the Iowa State Capitol with Queen Anne, Italianate, and Folk Victorian homes. Other designated areas include the Des Moines Register Buildings and several downtown landmarks. Certificate of Appropriateness required for exterior changes in designated districts. Look up historic district boundaries at: https://dsm.city/departments/permit_and_development_center-division/pages/historic_preservation
Frequently Asked Questions
Can I build an ADU in Des Moines?
Yes. Des Moines, IA allows accessory dwelling units. On a single-family lot you can build 1 ADU per lot.
How big can an ADU be in Des Moines?
The maximum size for a detached ADU in Des Moines is 900 square feet.
How long does it take to get an ADU permit in Des Moines?
The typical ADU permit timeline in Des Moines is Des Moines Permit and Development Center: ADU permits typically 3-6 weeks for plan review. Construction 2-7 months. Des Moines has a streamlined online permit portal.. Total estimated permit fees are $800-$3,500 total permit fees.
Do I need extra parking for an ADU in Des Moines?
No, Des Moines does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Des Moines?
No, owner-occupancy is not required for ADUs in Des Moines.
Source: Des Moines Code of Ordinances Chapter 134 (Zoning); Des Moines Building Code. Last verified April 6, 2026. View source