Anchors, Braces, Tools, and Cement Footings
Fence Braces: Do You Need Them?
The aim of fence braces is to counter sideways stress. If your fence weighs a lot, or there’s a snow load on it, or a tree branch falls on it, the fence will experience sideways stress. if the stress is too strong it can tilt or bend the corner posts, as well as all the line posts between the corners, so it’s definitely something to avoid.
A good way to avoid it is with fence braces at the corners, ends, and gates. Put an earth anchor or braced post at or near each corner, gate, and end (an “end” being a place where the fence butts up against a building, wall, or other fence). Then, when a sideways stress comes down the line it won’t do any harm because the fence braces will counteract it and nothing will move. Your fence will be protected.
Well then, Do you need this protection? The answer is “Not in all cases.” For instance, where you are using trees as posts corner bracing is not needed because the trees won’t move — and so they will provide any necessary bracing. Likewise, if no great sideways stress is expected you don’t need fence braces. Suppose your fence is short, protecting a small garden, and not in the way of falling branches. Then chances are it can deal with modest amounts of snow without bracing. Or suppose you are planning a long poly fence in California and do not anticipate either large falling branches or massive deer impacts. Our polypropylene is really strong, but it is also really light, so again the chances are you don’t need bracing.
Choosing the Right Fence Braces
But suppose you are using metal hexagrid fencing, which weighs more, or are in a snow-prone area or a place where tree branches can fall on the fence. Then, especially as the fence gets longer, you can see the potential for sideways stress increasing and you should consider fence braces.
So, what sort of bracing should you get? The best and least expensive bracing is provided by earth anchors. Ours have a propeller-like screw at the end of a long shaft and an estimated pullout strength of 2,000 pounds. Just put a rod through the anchor’s handle, screw the anchor into the ground at roughly a 45 degree angle (this can be dicey if rocks or roots are in the way), keep going until only the handle pokes out of the ground, and attach the handle to the top of the corner post with a length of heavy wire.
The problem is where to attach the anchors. If you attach them to the corner posts you will only need one anchor per post — installed about halfway around the corner’s exterior angle. However, there will then be a cable hanging off the corner that can make trouble for lawnmowers and running children. To avoid having any cable outside the fence line, install the next post over (let’s call it the corner “approach” post) a little closer than usual to the corner, screw your earth anchor into the ground right along the fence line, headed from the corner approach post toward the corner post, and attach it to the top of the corner approach post. This leaves the small distance between these two posts unbraced, but since the distance is really short it doesn’t matter. Of course, since each corner has two corner approach posts, you will need two earth anchors per corner instead of one; but they cost so little (about $10 each) it doesn’t make much difference.
Similarly, you should put your bracing anchors on end approach posts rather than end posts and on gate approach posts rather than on gate support posts. Doing this works well on mid-length to long deer fences. But what if your fence is short, say 40 feet or less on a side? In that case your corner approach post will go a quarter to a half of the distance to the next corner, and the length of fencing protected will range from very short to nil. Here the best course is to abandon earth anchors and decide whether to use corner and end/gate bracing posts, or else to forego bracing altogether.
Corner and end/gate bracing posts are ordinary round metal posts with one or two bracing posts attached to them at a roughly 45 degree angle. They are expensive, but the cost is mitigated by the fact that each of them replaces one regular post. So if you face a major threat from heavy snow, falling branches, or repeated deer impacts, go ahead and use them even though your fence is short.
Tools: The Manual Post Driver
There are lots of ways to install metal posts. One can use a post-hole digger, or if the ground is really tough one can rent a mechanical auger. But the first method is time-consuming and the second is expensive. So unless the soil is rock-hard, a better way to install posts is with a manual post driver.
You can get fancy drivers; but ours, the better basic model, works just as well. You don’t need to get way up in the air to drive in nine or even ten-foot posts. Just slip the driver (a heavy tube closed at one end with two long handles) over one end of the post. Then get up on one of those two-step affairs you use to move dishes in the pantry; put the post bottom where you want it to enter the ground; raise the driver up a bit; and drop it on the post. This typically drives the post into the ground 2 to 6 inches, and repeating this action will soon get the post down to the right depth. It’s really very simple.
Tools: The Digging Bar
Of course, rocks and roots can block the descending post. If that happens, you may need to pull the post out and start over. Or else, you may want to start with a digging bar and “prove out” a path for the post before you drive it.
To do this, take the digging bar (a heavy metal bar like a crowbar that instead of being bent is straight). Push or tap the bar’s pointed end into the ground a few inches; rotate it to enlarge the path; push or tap it down a few more inches; and repeat the process until you have reached the necessary depth. Now, when your take up your driver, you will know the post has an open path.
The digging bar offered on this site is a four-footer well-suited to getting two feet down. This tool is less expensive than most digging bars available in local stores. However, if you need to go deeper than 2 feet, as you do when installing drive sleeves, we recommend that you get a 5 or 6-foot digging bar locally.
We no longer recommend lots of cement footings. Here’s why: If a pull or load on your fence is sufficient to tilt posts lacking cement feet, then it’s likely to bend those same posts when they have cement feet–and tilting is easier than bending to correct. In this vein, current knowledge says it’s best to put your posts close enough together and do enough bracing (assuming the fence will face snow loads, falling limbs, or repeated deer impacts) so that tilting or bending is unlikely. Then limit your cement footings to anchor posts (those posts that are brace posts or that have earth anchors attached to them). This prevents sideways stress from being transferred downward and pushing the anchor post into the ground.
If you are using corner/end/gate braces instead of earth anchors, it’s a good idea to put both the main posts and the bracing post or posts in cement footings. Since the main post comes with a drive sleeve, this means putting the drive sleeve in a cement footing, which is perfectly all right. In the case of the side braces, one can substitute “dead men” (cement blocks placed so as to block the post ends) for the cement footings. This approach involves a bit less labor that the footings; but it is also less effective–because if a block is not properly aligned the blocked post can move.
Happily, in places where no earth anchors or brace posts are called for, cement footings are not needed.