A bill for an act relating to county and city regulation of accessory dwelling units.

This bill requires Iowa counties and cities to allow at least one accessory dwelling unit (ADU) - a secondary home on the same lot as a primary residence - in zoning districts where single-family homes are permitted. It sets size limits (max 1,000 sq ft or 50% of the main house size, excluding unfinished basements, garages, decks, and unheated porches) and restricts local governments from banning ADUs solely due to historic preservation rules unless a commission documents specific historical incompatibility. Homeowners seeking to build ADUs and local governments creating zoning rules are directly affected. The bill clarifies that historic district restrictions must be justified by a commission’s written determination, replacing prior broad exemptions.