Johnson County, IA Zoning Overlays & Bonuses: Density Bonus Law (2026)

8(G) of the Unified Development Ordinance, Volume Two of the county code, which governs subdivision design across Johnson County's unincorporated area. Subsection (G)(1), Density Bonuses, applies only to residential subdivisions platted in the AR, RS, and RM zoning districts. A subdivider qualifies by placing 50 percent of the total subdivision acreage into outlots dedicated to open space, agriculture, preservation, or infrastructure, but road right-of-way does not count toward that 50 percent. Meeting the threshold allows the plat to carry 25 percent more dwelling units than the district's standard density table permits.

8(G)(2) for subdivisions of ten or more buildable lots in the R district that preserve or restore Sensitive Areas under Chapter 8:3, and a subdivider who qualifies for both the density bonus and a lot-size bonus can combine them, reaching up to 30 percent of lots between two and five acres. Because the bonus is a subdivision design incentive rather than a use permitted by right, it is reviewed by the Planning, Development and Sustainability Department and the Zoning Administrator as part of preliminary and final plat approval, not through a separate rezoning.

The Comprehensive Plan, adopted under Iowa Code Chapter 335, guides which preferred densities and outlot configurations the county will accept. Subdividers proposing chain subdivisions must include all lots created after this ordinance's adoption when calculating whether the density-bonus threshold is met, so incremental phased development cannot dodge the 50 percent outlot requirement by splitting a project into smaller filings.