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GRADE · PANELS · GAPS

Plan a fence on a slope

A 100 ft run rising 48 in needs 13 equal bays at an 8 ft maximum. Each bay rises 3.7 in; a level stepped panel leaves up to 5.7 in below its low end with 2 in of clearance at the high end.

Sources checked

Your numbers

Measure the elevation difference from one end of the run to the other.

Use the maximum post spacing permitted by your chosen fence system.

Show panel layout

Your estimate

3.7 in rise per bay

13 equal bays across 100 ft; 14 posts for a straight line with no gate.

Low groundHigh ground
First 4 of 13 equal bays, schematic. The ground is assumed to rise evenly; measure each real bay before ordering panels.
  • Actual bay width
    7.69 ft
  • Ground grade
    4.0% · 2.3°
  • Low-end opening with level panelsChosen clearance plus rise across one bay.
    5.7 in

Racked panels follow the ground only when the specific product permits that angle. These counts do not size posts, footings or gates.

How the slope calculation works

Measure horizontal fence run and the total elevation change. Divide the run into equal bays no wider than the spacing you enter. The total rise divided by the bay count gives rise per bay. For a level stepped panel, the low-end opening equals the high-end clearance plus that rise. The grade is total rise divided by horizontal run.

This assumes a constant grade. A dip or steep patch can have a larger opening than the average shown here. Measure each bay on the ground and check your panel maker’s maximum post spacing and whether that product can rack to the actual angle.

Stepped or racked panels?

Stepped panels remain level and leave a wedge-shaped opening at their low ends. Racked panels follow the grade and keep a steadier ground gap, but only a panel designed for that amount of rack can be installed that way. Bufftech’s installation guide describes both methods for its products; its limits are product-specific. The diagram compares geometry, not a structural approval.

A gate on a slope needs its own swing clearance and post layout; this straight, gate-free calculation does not size one. Check the local height and property-line rules before construction.

Fence slope questions

How much does each fence panel step on a slope?

On the 100 ft example rising 48 in, 13 equal bays each rise 3.7 in. Measure each real bay because a uniform average can hide a steep section.

How big is the gap under a stepped fence?

The low-end opening is the clearance you leave at the high end plus the ground rise across that bay. In the example it is 5.7 in, using 2 in of high-end clearance and 3.7 in of rise.

Can vinyl or aluminum panels follow the slope?

Some product systems allow panels to rack, but the permitted angle differs. Confirm the installation instructions for your exact panel; if it cannot rack enough, a stepped layout or a different system is needed.

A planning aid, not an engineering calculation: your local code and building inspector have the final word. Terms