Des Moines

Iowa enacted strong statewide ADU preemption in the 2025 session. Senate File 592 was signed by Governor Kim Reynolds on 2025-05-01 and took effect 2025-07-01. The bill requires every Iowa city and county to allow at least one ADU on every lot containing a single-family residence. ADU size is capped at the larger of 1,000 sqft or 50% of the primary residence size. Cities and counties may not impose ADU-specific requirements that are more restrictive than those for single-family residences in the same zone — including height, setbacks, lot size, lot coverage, density, parking, utility separation, impact fees, rental restrictions, or aesthetic/architectural standards. Permit applications that meet requirements must be approved without a hearing within the same timeframe as a single-family residence. Local actions inconsistent with the law are void. The only carve-outs are state historic building code, deed restrictions, and HOA rules.

Iowa does not operate an ADU-specific statewide loan, grant, or forgivable-loan program. The Iowa Finance Authority (IFA), now operating under the Iowa Economic Development & Finance Authority umbrella, administers general first-time-homebuyer mortgage and down-payment-assistance programs (FirstHome, Homes for Iowans) and a Multifamily Loan Program for rental development; none target ADU construction directly. ADU costs may be financed through standard renovation or construction loan products under these IFA programs when the ADU is part of a qualifying primary-residence purchase or refinance.

• FirstHome Program
• Homes for Iowans Program
• Multifamily Loan Program

Iowa's primary state-level ADU program is the SF 592 (2025) preemption framework: by-right ADUs on every single-family lot statewide, with strict caps on what local regulation can impose. There is no statewide pre-approved ADU plan catalog, no statewide ADU rebate, and no statewide ADU impact-fee waiver as a separate program — but SF 592 itself prohibits ADU-specific impact fees beyond what would apply to a single-family residence, which functions as a statewide impact-fee floor. Streamlined ministerial review is mandated by SF 592.

• SF 592 ADU-by-right framework — Cities and counties must allow at least one ADU on every single-family lot, ministerially, on the same approval timeline as a single-family residence. ADU-specific restrictions on size (above the 1,000 sqft / 50% cap), height, setbacks, lot coverage, density, parking, utilities, impact fees, rental, and aesthetics are barred.
• SF 592 implicit impact-fee cap — Local impact fees specific to ADUs (beyond the single-family fee schedule) are barred. ADUs cannot be charged separately above what the underlying single-family use would bear.