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How to Build a Split Rail Fence

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The split rail, or post and rail, fence is essentially a rustic version of a post and board fence style and is similarly a good choice for a decorative accent, for delineating areas, or for marking boundaries without creating a solid visual barrier. Typically made from split cedar logs, the fence materials have naturally random shaping and dimensions, with imperfect details and character marks that give the wood an appealing hand-hewn look. natural weathering of the untreated wood only enhances the fence’s rustic beauty.

The construction of a split rail fence couldn’t be simpler. The posts have holes or notches (called mortises) cut into one or two facets. The fence rails have trimmed ends (called tenons) that fit into the mortises. No fasteners are needed. Posts come in three types to accommodate any basic configuration: common posts have through mortises, end posts have half-depth mortises on one facet, and corner posts have half-depth mortises on two adjacent facets. The two standard fence styles are two-rail, which stand about three feet tall, and three-rail, which stand about four feet tall. rails are commonly available in eight- and ten-feet lengths.

In keeping with the rustic simplicity of the fence design, split rail fences are typically installed by setting the posts with tamped soil and gravel instead of concrete footings (frost heave is generally not a concern with this fence, since the joints allow for plenty of movement). This comes with a few advantages: the postholes are relatively small, you save the expense of concrete, and it’s much easier to replace a post if necessary. plan to bury about a third of the total post length (or 24 inches minimum). This means a three-foot-tall fence should have 60-inch long posts. If you can’t find long posts at your local home center, try a lumberyard or fencing supplier.

How to Build a Split Rail Fence

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    Determine the post spacing by dry-assembling a fence section and measuring the distance between the post centers. Be sure the posts are square to the rails before measuring. 

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    Set up a string line using mason’s string and stakes to establish the fence’s path, including any corners and return sections. Mark each post location along the path using a nail and plastic tag.

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    Dig the postholes so they are twice as wide as the posts and at a depth equal to 1⁄3 the total post length plus 6". Because split posts vary in size, you might want to lay out the posts beforehand and dig each hole according to the post size.

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    Add 6" of drainage gravel to each posthole. Tamp the gravel thoroughly with a digging bar or a 2 × 4 so the layer is flat and level.

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    Set and measure the first post. Drop the post in its hole, and then hold it plumb while you measure from the ground to the desired height. If necessary, add or remove gravel and re‑tamp to adjust the post height.

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    Brace the post with cross bracing so it is plumb. Add 2" of gravel around the bottom of the post. Tamp the gravel with a digging bar or 2 × 4, being careful not to disturb the post.

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    Fill and tamp around the post, one layer at a time. Alternate between 4" of soil and 2" of gravel (inset), tamping each layer all the way around the post before adding the next layer. Check the post for plumb as you work. Overfill the top of the hole with soil and tamp it into a hard mound to help shed water.

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    Assemble the first section of fence by setting the next post in its hole and checking its height. Fit the rails into the post mortises, and then brace the second post in place. Note: Set all the posts at the same height above grade for a contoured fence. For a level fence, see Variation, right.

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    Variation: For a fence that remains level across the top, set up a level mason’s line strung between two installed fence posts or between temporary supports. Set all of the posts so their tops are just touching the line.

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    Secure the second post by filling and tamping with alternate layers of gravel and soil, as with the first post. Repeat steps 5 through 9 to complete the fence. Tip: Set up a mason’s string to help keep the posts in a straight line as you set them.

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