Waukesha, WI Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard requirement
- 2 feet above regional flood elevation
- Fill extent
- At least 15 feet beyond structure
- Zone AO alternative
- FIRM depth + 1 ft, or 3 ft above grade
- Basement/crawl space floor
- 1 ft above regional flood elevation if floodproofed
- Penalty
- Forfeiture up to $50 per day
- Enforcing official
- Zoning Administrator
- Chapter adopted
- Ord. 2023-11, effective 9/5/2023
Summary
New construction and substantially improved homes in Waukesha's Flood Fringe District must have the lowest floor built to or above the flood protection elevation, which Municipal Code Chapter 24 defines as two feet of freeboard above the regional (base) flood elevation, with fill extending 15 feet past the structure.
All New Construction, including placement of Manufactured Homes, and Substantial Improvement of residential Structures, shall have the Lowest Floor elevated to or above the flood protection elevation on fill. The fill around the Structure shall be one foot or more above the regional flood elevation extending at least 15 feet beyond the limits of the Structure. No area may be removed from the Flood Fringe district unless it can be shown to meet §24.04(3);
Full Breakdown
Waukesha Municipal Code Chapter 24, Floodplain Zoning, adopted by Ord. 2023-11 on September 5, 2023, sets the elevation standard for building in a mapped floodplain. 07(3)(a)(i) applies that standard directly: any new residential structure, including a manufactured home, or any substantial improvement to an existing residential structure in the Flood Fringe District must have its lowest floor elevated to or above the flood protection elevation on fill, with the fill extending at least 15 feet beyond the structure and standing at least one foot above the regional flood elevation.
07(3)(a)(ii) allows a narrow exception: a basement or crawl space floor may sit just one foot above the regional flood elevation if the space is engineered watertight, with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads, and no floor of any kind may go below the regional flood elevation itself. 07(3)(k). 08(4) sets separate elevation rules for AO and AH zones: AO structures must be elevated to the FIRM-listed depth above the highest adjacent grade plus one additional foot of freeboard, or three feet above the highest adjacent grade if no depth is listed, while AH structures go to the flood protection elevation like Flood Fringe homes. 10, which require a registered engineer's or architect's certification and a FEMA Floodproofing Certificate before a permit issues. 11.
Violations & Fines
Placing or maintaining any development in a Waukesha floodplain that fails to meet Chapter 24's elevation standards is a public nuisance under Section 24.15(1), and the City, the State, or any citizen may sue to enjoin or abate it under Wis. Stat. § 87.30. Section 24.15(2) also authorizes a forfeiture of up to $50 for each offense, with each day the violation continues counted as a separate offense. The Zoning Administrator and designees enforce the chapter under Section 24.15(3).
Frequently Asked Questions
How high must a new home's lowest floor be built above base flood elevation in Waukesha?
Can a Flood Fringe home in Waukesha have a basement?
What happens if a structure in Waukesha's floodplain isn't elevated correctly?
Do commercial and industrial buildings face the same elevation rule?
Sources & Official References
Other rules in Waukesha
Compare Waukesha to another location·View the Wisconsin environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.