Iowa 2025-2026 Regular Session

Iowa House Bill HSB618

Introduced
1/22/26  

Caption

A bill for an act relating to county and city regulation of accessory dwelling units.(See HF 2252.)

Impact

HSB618 will amend existing state laws to specify that the size of an ADU cannot exceed 1,000 square feet or 50% of the primary dwelling's size, whichever is larger, and certain considerations such as unfinished basements are excluded from this calculation. Additionally, the bill reduces restrictions that might currently prevent the construction of ADUs in historic districts, allowing these units to be regulated only based on local historic preservation standards. This could potentially increase the development of ADUs in areas where they might not have been previously permitted, effectively altering local zoning frameworks.

Summary

House Study Bill 618 addresses regulations surrounding accessory dwelling units (ADUs) within the state of Iowa. The bill mandates that counties and cities must allow at least one ADU on a lot that already has a single-family residence, provided that the location falls within a zoning district that permits such residences. This legislation aims to streamline the process for creating additional housing options in response to growing concerns about housing availability and affordability, as it can potentially increase the housing supply in residential areas without requiring significant new infrastructure.

Contention

Notable points of contention surrounding HSB618 may arise from local governments' concerns about loss of regulatory authority. Some community members fear that the bill could mandate more housing development without sufficiently considering local contexts, which could impact neighborhood character or historic cohesion. Others argue that this bill represents an important step towards increasing the availability of diverse housing options, an essential issue as cities face increasing population pressures. Ultimately, as with many housing-related bills, the discussions surrounding HSB618 will likely involve balancing community preferences with the pressing need for more housing.

Companion Bills

IA SSB3070

Related A bill for an act relating to county and city regulation of accessory dwelling units.(See SF 2369.)

IA HF2252

Replaced by A bill for an act relating to county and city regulation of accessory dwelling units.(Formerly HSB 618.)

Previously Filed As

IA SSB3070

A bill for an act relating to county and city regulation of accessory dwelling units.(See SF 2369.)

IA HF2252

A bill for an act relating to county and city regulation of accessory dwelling units.(Formerly HSB 618.)

IA HSB162

A bill for an act relating to county and city regulation of accessory dwelling units.(See HF 947.)

IA SF2369

A bill for an act relating to county and city regulation of accessory dwelling units. (Formerly SSB 3070.) Effective date: 07/01/2026.

IA SSB1182

A bill for an act relating to county and city regulation of accessory dwelling units.(See SF 592.)

IA HF947

A bill for an act relating to county and city regulation of accessory dwelling units.(Formerly HSB 162.)

IA SF592

A bill for an act relating to county and city regulation of accessory dwelling units. (Formerly SSB 1182.) Effective date: 07/01/2025.

IA SB543

Accessory dwelling units and junior accessory dwelling units.

IA HB2783

Accessory dwelling units; population; regulations

IA SB673

Relating to municipal and county regulation of accessory dwelling units; authorizing a fee.

Similar Bills

CA AB1154

Junior accessory dwelling units.

CA SB9

Accessory Dwelling Units: ordinances.

CA AB2127

Accessory dwelling units: private sewage disposal systems.

CA AB956

An act to amend Section 50515.

CA AB1055

Accessory dwelling units: proof of residential occupancy requirements.

CA SB543

Accessory dwelling units and junior accessory dwelling units.

AZ HB4028

Accessory dwelling units; requirements

TX SB673

Relating to municipal and county regulation of accessory dwelling units; authorizing a fee.