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How to Set Fence Corner and End Posts

Master corner and terminal post installation. Learn proper footing depth, diameter, alignment strings and bracing for tensioned runs.

Published 4 min read

Corner posts and end posts (collectively known as terminal posts) are the foundational backbone of any fence system. Whether you are erecting a residential cedar privacy fence, a chain-link perimeter, or a high-tensile agricultural pasture, line posts simply keep the fence upright; terminal posts carry the tension, resist corner loads, and anchor gate swings.

If a terminal post shifts by even an inch, the entire fence line will sag, rails will pull out of brackets, and gates will bind.

Here is how to properly locate, dig, brace, and pour concrete footings for permanent corner and end posts.

Why Terminal Posts Require Special Engineering

Terminal posts experience directional forces that standard intermediate line posts never encounter:

  • End posts (terminations): Carry one-way horizontal pull from rails, wires, or gate hinges without an opposing counterbalancing load on the other side.
  • Corner posts (90-degree turns): Carry lateral tension from two perpendicular fence runs. The resulting vector pulls the corner diagonally inward toward the center of your yard.
  • Gate posts: Must withstand continuous cantilevered dynamic impact from swinging and latching heavy gate frames.

Because of these extreme mechanical loads, corner and end posts must always be larger in dimension, buried deeper in the ground, and set in wider concrete footings than standard intermediate line posts.

Step 1: Locate Corners Using Property Pins and Batter Boards

Never eyeball a corner post location:

  1. Locate legal survey pins: Use a metal detector to locate iron survey pins buried at your property corners. Setting a corner post on your neighbor’s property can lead to costly court battles and forced removal.
  2. Erect batter boards: Drive two wooden stakes outside each corner and fasten a horizontal crosspiece. Run mason line from batter board to batter board slightly offset from the actual fence boundary.
  3. Verify 90-degree angles using the 3-4-5 rule: Measure 3 feet along one line from the intersection, 4 feet along the perpendicular line, and measure diagonally between the two marks. The diagonal distance must equal exactly 5 feet. If it does not, adjust the string lines until the intersection forms a perfect right angle.
  4. Drop a plumb bob: Hang a plumb bob from the intersection of the string lines down to the grass to mark the exact center point of the corner hole.

Step 2: Hole Dimensions and Frost Depth Rules

Terminal posts require substantially larger holes than intermediate posts:

  • Diameter rule: A post hole diameter must be at least 3 times the diameter or width of the post. For a 4x4 post (3.5 inches actual), dig a 10 to 12 inch diameter hole. For a 6x6 post (5.5 inches actual), dig a 16 to 18 inch diameter hole.
  • Depth rule: Terminal posts must be set into the ground to a depth equal to at least 40% to 50% of the above-ground fence height, plus an additional 6 inches of gravel base. In freezing regions, the bottom of the footing must extend at least 6 to 12 inches below the local frost line to eliminate frost jacking.
  • Bell-shape the bottom: Widen the bottom of the hole slightly with an auger or manual digging bar so the hole resembles an inverted cone. This prevents the concrete plug from ever lifting out of the soil.

Step 3: Temporary Bracing Before Pouring Concrete

Never pour concrete into an unbraced corner post hole:

  1. Place 4 to 6 inches of crushed gravel into the bottom of the hole for water drainage.
  2. Stand the post on the gravel bed.
  3. Use a 4-foot spirit level or a two-way post level attached with rubber bands to verify the post is perfectly plumb on both adjacent faces.
  4. Fasten two 2x4 wooden diagonal braces to the post using duplex nails or exterior screws. Stake the opposite ends of the braces firmly into the ground with wooden stakes.
  5. Double-check plumb after staking the braces. The post should not budge when nudged.

Step 4: Pouring and Tooling the Concrete Footing

  1. Mix commercial concrete to an oatmeal-like consistency. Wet, soupy concrete weakens the final compressive strength and promotes post cracking.
  2. Shovel concrete around the post in 6-inch increments, rodding the mix with a rebar or wood stake to eliminate air pockets.
  3. Fill to within 2 inches of the surrounding turf.
  4. Trowel the top surface into a pronounced crown or pyramid that slopes downward away from the post on all four sides. This sheds rain away from the timber seam.
  5. Allow the concrete to cure for a minimum of 48 to 72 hours before attaching fence rails or hanging heavy gates.

Tools for Sizing and Material Takeoffs

Calculate post requirements and footing dimensions before buying lumber and concrete:

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