Yellowstone County, MT Fence Regulations: Fence Permit Requirements (2026)

Section 27-1209.A governs when fence work in unincorporated Yellowstone County needs sign-off from the planning department. The section defines "fence" broadly to mean any fence, wall, or hedge, so a living hedge used as a screen is regulated the same way as a wood or chain-link fence. Any fence greater than three feet and up to seven feet in height requires a fence permit under Section 27-1619; anything over seven feet requires the more involved Zoning Compliance Permit under Section 27-1628, the same permit track used for other zoning-regulated site changes. A fence at three feet or under needs no permit under this section at all. No fence, wall, or hedge of any height may be erected or maintained inside a public right-of-way, full stop.

Height itself is measured precisely: Section 27-1209.B defines it as the vertical distance from the top rail, board, or wire down to the ground directly below, measured from the inside of the fence, not the outside face a neighbor sees. That measurement point matters on sloped lots, where the inside and outside grade can differ by more than a few inches. Once a fence clears the permit threshold, it also has to meet the article's height and setback limits, including the four-foot maximum height that applies within a required front yard setback under Section 27-1209.C.