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

40's Lot Coverage and Open Space subsection is the one explicit percentage-based coverage cap written into Waukesha's Chapter 22 zoning code. It applies to the M-3 Limited Business and Industrial Park District, created for office, corporate headquarters, and light manufacturing uses arranged in a park-like setting, and it limits the combined footprint of buildings, accessory structures, and surface parking and driveways to seventy-five percent of the lot. The other twenty-five percent must be landscaped open space free of buildings, accessory structures, and parking or driveway surface, though that open space is allowed to double as stormwater retention or detention area rather than pure lawn or planting.

The same subsection layers on an operational limit tied to coverage: every use in the M-3 district must be conducted entirely inside a building, and any outdoor storage is capped at no more than ten percent of the building's area and must be screened from view by an approved solid wall, fence, or hedge. Elsewhere in Chapter 22, most districts regulate site coverage indirectly through minimum lot area and width, required setbacks and yards, and minimum floor area rather than a stated maximum coverage percentage, which makes the M-3 seventy-five percent cap the clearest numeric lot-coverage ceiling in the zoning code. 52, to adjust those standards.