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How to build a Post-and-Rail Fence

Once you have your post holes drilled or dug, you are ready to start building.  Keep in mind that while post-and-rail’s advantage over pre-built panels is that you can make it any size, you are still limited by the length of dimensional pressure-treated lumber.  Therefore, your posts really can’t be set more than eight feet apart (though they can be less than eight feet apart).

  1. Dig your post holes two feet deep and set the posts in place. Put one stake in the front, and one to the side, each about 3 or four feet from the post.  Attach a small board (2×4 or smaller) to the stake using a wood screw, then check that the post is vertically level before screwing the other end of the brace in place.  Do the same in the perpendicular direction, and double check that your post is still the distance you want from your other posts. If it is, set the post in concrete and fill the hole back up to ground level. (Tip: you don’t need to go to the trouble of mixing your concrete.  Just pour the dry concrete mix into the hole and cover.  Moisture from the ground will be drawn into the mix and you’ll have a hard, solid base within two days.  If you’ve dug two feet deep and filled the hole, don’t worry.  Those posts aren’t going anywhere.)
  2. If for some reason you can’t set a post in concrete, you can buy these fence post spikes at Home Depot.
    fence post ground spike

    fence post ground spike

    I, for example, had to run the fence along an Allan Block retaining wall, which is back-filled with gravel.  This was nearly impossible to dig, and I couldn’t maintain a hole to set the post in.  In such cases, the fence post spike is easily driven in by placing a small scrap piece of 4×4 post into the square opening and pounding it in with a sledge hammer.  Home Depot sells these for 7.99 for a fixed one-piece, or 12.99 if you want a swivel top.  I recommend the swiveling top because it is nearly impossible to maintain a perfectly level spike.  The rocks in the ground will shift it somewhat, and then you can easily readjust for level once it is in place.

  3. Once your posts are in place and the concrete is set, you are ready for your rails.  Mark the height you want the rails to be, then clamp the rail to the post, and adjust as necessary.  Use two green or brown treated 3″ screws to attach the rail to the posts.  The rails should be 2×6 pressure treated, and if your posts are eight feet apart, you’ll want your rails to be 16 feet long so you can stagger the joints.  Staggering the joints gives the fence added strength.

    staggered fence rail joints

    staggered fence rail joints

  4. If your slope is not consistent, you’ll need to make vertical cuts to your rails at the post.  Using your level, draw a vertical line over the rail at the middle of the post.  Set your circular saw to 1-1/2″ deep, and cut your vertical line.  Clamp the new board in place, overlapping the previous rail, and mark the top and bottom of edge you just cut and draw a line on the new rail to match that cut.  Trim off the new rail and attach to the fence post. This will make a nice vertical joint for your fence post rails.
    post and rail fence joint
    post and rail fence joint
  5. At each end of your fence, you’ll be left with one 8 foot rail.  Try to finish it off right to the outer edge, rather than the middle of the post.  Aesthetically, it just looks better, and you can always trim it back to the middle if you decide to continue the fence further later.  In the end, your fence will look something like this.

    post and rail fence down hill

    post and rail fence downhill

As you can see, the fence isn’t finished, but I’ve started adding fence boards.  Privacy was important, and as soon as we got the main posts up, my wife wanted those boards to go in.  More on adding fence boards next!




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  1. [...] Trouble was, we’d used up all the warm months doing somewhat more urgent projects like building the fence, building the play structure, and painting the hardie board.  But Christmas is coming, and green [...]

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