Janesville, WI Building Setbacks & Zoning: Lot Coverage Limits (2026)

Section 42-440(a)(2) defines green area as land that must be permanently provided and properly maintained on each lot devoted to a permitted or conditional use, unobstructed to the sky and off-limits to service driveways, walks, off-street parking spaces or loading berths; it must instead be usable for greenery, recreation and other outdoor leisure activities, with at least half of the requirement falling in the front or corner side yard between the principal building and the property line. Section 42-440(a)(3) separately defines open space as land that may include driveways, walks, parking, pools and tennis courts, and green area, but must remain free of any building or structure.

The district-specific standards translate those definitions into hard percentages: Section 42-440(b)(1)g requires 25 percent of the gross lot area in the R1 District to be devoted to green area, and Section 42-440(b)(1)h requires 40 percent of the gross lot area left in open space, with green area countable toward that 40 percent. The same 25 percent green area and 40 percent open space figures repeat for the R1D, R2 and R3M Districts under their own (g) and (h) subsections, while R3 and R4 carry only the 25 percent green area requirement with no separate open space line.

Because open space excludes any building footprint, these percentages function as the city's functional lot-coverage ceiling: a principal building, its accessory structures and any impervious paving cannot together consume more than 60 percent of an R1 lot's area, and no more than 75 percent can be non-green surface.