Monroe County, FL Fence Regulations: Retaining Walls (2026)

Section 114-13(d) defines a retaining wall as a wall or similar structural device used at a grade change to hold soil on the up-hill side from slumping, sliding or falling, and folds it into the same rules that govern fences under Section 114-13. A retaining wall follows the setback and height limits that apply to fences on that lot, but with one hard ceiling: no retaining wall may exceed four feet, measured from the lowest existing adjacent grade, regardless of what a fence on the same property could reach.

Where a slope needs more than one wall stepped up the grade, the walls must be separated by a minimum distance equal to twice the exposed height of the lower wall, with an absolute minimum separation of two feet and a maximum required separation width of five feet, measured from the back edge of the lower wall to the front edge of the next wall up. If a retaining wall is topped with a fence, the combined height of the wall and fence cannot exceed the fence height limit that applies to that setback under Section 114-13(a) and (c).

Because retaining walls are treated as fences for setback purposes, they can generally sit anywhere on the lot, including on the property line, but they cannot block fire and emergency access, extend into wetlands or past the mean high tide line, or clear native vegetation from a required bufferyard, and any wall on Big Pine Key or No Name Key must also meet the additional Key Deer habitat standards in Section 114-13(c).