Waukesha, WI Fence Regulations: Retaining Walls (2026)
Key Facts
- Unengineered wall cap
- 4 feet maximum
- Governing section
- Municipal Code Sec. 22.17
- Certification required for taller walls
- Registered engineer, architect, or landscape architect
- Small grade-cut standard
- 2 ft or less: sod or masonry wall
- Rip-rap slope limit
- 1 ft vertical to 1 ft horizontal
- First-offense fine
- $10 to $2,500 plus costs
Summary
Waukesha caps an unengineered retaining wall at four feet under Municipal Code Sec. 22.17, the Preservation of Topography section. A taller wall needs a registered engineer, architect, or landscape architect to certify it will not collapse before the City will allow it between adjacent lots.
If the difference in grade between two (2) adjacent lots along a lot line is to be not greater at any point than two (2) feet, this difference in levels may be slopped toward or away from the lot line at a gradient of one (1) foot vertical or three (3) feet horizontal, and as soon as practical must be covered adequately with top soil and sodded to prevent erosion; or a retaining wall of stone or other suitable masonry material shall be constructed to preserve the higher ground. ... A difference in adjacent grades may be protected by a retaining wall providing that the wall is constructed in such a manner as not to collapse. No retaining wall shall exceed four (4) feet in height unless it has been engineered by a registered engineer, architect, or landscape architect who shall certify that such higher wall will not collapse.
Full Breakdown
17 regulates how property owners handle grade differences along a shared lot line. Where the difference is two feet or less, the owner may slope the ground at a gradient of one foot vertical to three feet horizontal and cover it with topsoil and sod, or build a retaining wall of stone or other suitable masonry to hold the higher ground; on a single lot, cuts or fills up to two feet and no more than 4,000 square feet follow the same standard. Where the grade difference exceeds two feet, sodded slopes are still capped at one-to-three, a rip-rap protected slope cannot exceed a one-foot-vertical-to-one-foot-horizontal gradient, and a retaining wall is allowed instead provided it is built so it will not collapse.
That is where the four-foot ceiling applies: any retaining wall over four feet must be engineered, with a registered engineer, architect, or landscape architect certifying the taller wall will not fail. 15, such as commercial or multi-family development, folds the retaining wall into that Plan Commission review of grading, drainage, and site improvements. 67.
Violations & Fines
Building a retaining wall over four feet without the required engineer, architect, or landscape architect certification is a violation of Chapter 22 enforceable by the Zoning Administrator under Section 22.67, which lets the City, the City Attorney, or a damaged neighboring property owner seek injunctive relief. Because Chapter 22 does not set its own dollar penalty, violations fall under the Municipal Code's general penalty schedule in Section 25.05: not less than $10 nor more than $2,500 for a first offense plus prosecution costs, and $100 to $5,000 for each subsequent offense, with every day the wall remains noncompliant counted as a separate offense.
Frequently Asked Questions
How tall can I build a retaining wall in Waukesha without hiring an engineer?
What do I need to build a retaining wall taller than four feet?
Does a retaining wall need Plan Commission approval in Waukesha?
Who enforces Waukesha's retaining wall rules?
Sources & Official References
Other rules in Waukesha
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