Quick Answer
Fence on sloped land following the contour where possible (running across the slope, not up and down). This reduces erosion, simplifies water management, and maintains consistent wire heights. Where fences must run up slopes, use closer post spacing (30–40 feet), stronger corner bracing, and install drainage crossings at every low point. Slopes over 25% require concrete corner posts and possibly specialized equipment.
Contour vs. Slope-Parallel Fencing
Contour fencing (across the slope): Wire runs level along the hillside. Advantages: consistent wire height, minimal erosion risk, easier to maintain wire tension. Disadvantages: paddock shapes may be irregular; fence lines may not align with natural property boundaries.
Slope-parallel fencing (up and down the hill): Wire runs perpendicular to contours. Problems: water concentrates along the fence line and erodes; wire tension varies at the bottom (too tight) and top (too loose) as the slope changes grade; posts on the downslope side lean from soil movement over time.
Wire Tension on Slopes
Gravity creates uneven tension on a fence running up a slope — the downslope end bears more wire weight than the upslope end. On moderate slopes (5–15%), this is manageable by adding one extra line post every 20–30 feet to support wire weight. On steeper slopes (>15%), use in-line tensioners every 200–300 feet to maintain consistent tension across grade changes, and angle the tensioner mounts to match the wire angle.
Corner and End Post Placement
Place corner posts at the top and bottom of slope runs, not partway up the slope where wire tension changes are greatest. A corner post on a grade change point must deal with both the horizontal wire tension and the vertical component of wire weight — this requires a double H-brace and typically concrete post setting.
Erosion Prevention
- Seed 4–6 feet on each side of slope fence lines with dense perennial grass before installing fence
- Install culverts or water gaps at every drainage concentration point
- Restrict livestock access to fence lines during wet periods to prevent vegetative damage
- Consider rock check dams in channels that form along upslope fence runs
Our Recommendation
Walk the proposed fence line after a rainstorm before installing — you'll see exactly where water flows and where erosion problems will develop. Plan drainage solutions at that stage, not as reactive repairs after damage occurs. The 30-minute pre-installation walk prevents the most common and expensive slope fencing mistakes.