Digging Holes 101

Using the Right Tools and Materials plus Digging Proper Depth Yields Strong Fences

Digging Holes 101

Since the dawn of agrarian culture, we’ve been inventing and reinventing ways to keep domesticated animals contained. Many things in our culture have radically changed such as how we communicate, but by in large, fence technology hasn’t really changed all that much. We still dig holes, stick poles in the ground and hang something between them, but we have refined the methods we use to dig those holes and how we bury those posts. Before you set out to build your livestock fence, there are a few things you should consider.

Picking a Post Hole Digger

Every homesteader needs a post hole digger at some point, but not all post hole diggers are created equal. There are many ways to dig a post hole, but the best choice for you will likely depend on a few factors. How deep do you need this post? What’s the terrain like? What’s the soil composition like? How many posts do you need to sink and can you handle the physical demand of the tool? Ask yourself these questions and let them guide you when you set out to purchase a post hole digger, but first, let me give you some ideas.

Manual Post Hole Digger

Manual post hole diggers were invented shortly after God invented dirt, as far as I can tell. We’ve all seen these contraptions with their steel clam shell design and long wooden handles, and I’m sure they’ve been mistaken for some sort of torture device at some point. Many who have used one of these post hole diggers will likely tell you that they are, showing you the blisters to prove it.

The theory is simple enough; open the jaws, put the blade into the ground, close jaw, pull out dirt and repeat. Simple to understand, but not always simple to do. If you have limited upper body strength, a bad ticker or a short temper, this device will likely not work well for you. This style of post hole digger also will not work well in regions that have lots of rocks in the soil, like the New England states.

For those of you who have soft or even sandy soils largely devoid of granite potatoes, then this style of post hole digger may be just fine for you. The price is right, being the cheapest post hole digger tool you can find, and if you have one or two shallow holes to dig, it just might be your best bet. Just make sure you don’t dig a hole too shallow because that and other common fencing mistakes can make your life miserable.

Two-Man Auger

Gasoline-powered, twin-operator post hole digger augers make digging holes much faster and easier than doing it by hand. For those of us who have soft dirt with little rock, these tools can be just what the doctor ordered. For those of us who live in rock-strewn country, using one might end with orders from your doctor.

If your gas-powered auger catches between rocks, it might take you for a ride, so be careful when operating one. I seldom suggest that anyone buy one of these post hole diggers, not just because they can be dangerous, but also because they require a second set of hands, upping the labor cost and inconvenience. These tools cost a lot for what they are and many of them get used so infrequently that the carburetors gum up or the fuel lines degenerate before the next occasion. Unless you and your best friend plan on digging holes every other weekend, these are really not a great option.

If you do find yourself in need of one for a temporary job, then rent one. It makes far more sense to borrow one from the local power shop than it does for you to buy one. If you do buy one, make sure you use fuel stabilizer, or even better, buy “tool fuel” instead of pump gasoline. Run your tool out of gas before storing it too, since varnished fuel will clog your carburetor and the new pump gas will eat your fuel lines or seals.

PTO-Powered Auger

Now we’re talking! PTO (power take off), or hydraulically driven post hole diggers, are usually the best way to sink posts, especially if you have a lot of holes to dig. If you have a tractor with a PTO, I encourage you to buy a used post hole digger for your three-point hitch. These units are little more than a frame, a gearbox, PTO shaft and a big screw, so there’s not much to fail. If you can’t find one for a deal on Craigslist.org, which is a great place to find common farm implements for cheap, shop around and find a reasonably priced unit. We don’t use our post hole digger often, but the few times we have was enough to justify the cost.

If you are lucky enough to own a skid steer, I envy you. Hydraulic post hole digger attachments are readily available for rent or purchase for most skid steers, and even though they are more expensive and slightly more complicated, they do a fantastic job. Running a post hole digger on a skid steer is much more comfortable and far easier to use than one mounted on the back of a tractor because the auger is right in front of you, instead of directly behind you. If you have the option, the skid steer approach is much easier on your neck.

The machine-powered auger may be the way to go, but it has its drawbacks. The expense of buying the skid steer or tractor makes it a prohibitively expensive way to dig holes. If you already have the machine then it’s a simple add-on that will make your machine more versatile, and usually well worth the expense. Machine-powered augers work well in clay and even rocky soil, just be prepared to replace a few shear pins along the way. Also, consider the terrain you’re working in since steep grades and low-hanging branches make life difficult when navigating a tractor or skid steer to the next dig.

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When you run into tough rocky areas, backhoe attachments are king.

Backhoes

Sometimes you just need to pull out the big guns. Especially in New England, even PTO-powered post hole diggers might not do the trick. In really rocky soils, a backhoe may be your only course of action. Many times I’ve had to throw in the towel and use my backhoe to pluck some “big bones” out of the ground so I could sink my post where I wanted it. It wasn’t pretty, but you better believe the hole got dug. A word of caution; digging holes with a backhoe can be more fun that you think. If you’re not careful, you may find yourself digging a pond with a backhoe before you know it!

Backhoe attachments are expensive, even if you have the tractor where you can hook it. Backhoes are an effective way to bury a post, but they’re not a fast way to do it either, since backfilling a big gaping hole takes time. Consider this a last resort, but when faced with a monster rock lurking under the surface, it can be a satisfying way to sink a post.

Pick Your Poison

No single post hole digger will fit every person, situation or budget, but take these into consideration before you lay down your hard-earned cash and buy yourself one. If you can borrow or rent one of these diggers, you may come out ahead of the game, especially if you don’t plan on using it often.

All About Posts

Fence post depth, size, and anchoring systems can make or break your fence line. Despite what some people believe, making a long-lasting fence is not always as simple as sinking a post in the ground and moving on to the next post. There are a few great tricks you should know before you start making holes with your post hole digger.

Choosing The Right Post

Picking the right post for the job is just as critical as setting your fence post depth correctly; possibly even more so. Cedar poles are a great way to hang fence wire. Depending on your needs, you could investigate the use of fiberglass fence post rods and steel T-posts if your application permits. Economics will likely play a big role in your decision making.

Classic cedar poles make for a good low-cost construction technique, but they’re not up to the task of supporting and bracing your corners or gates. The corner posts, posts stationed at rises and valleys as well as posts that your gates hang on are under much more stress. Compared to your interstitial posts that simply support your fencing from flopping or drooping, these posts need to be more substantial.

For fence posts charged with important tasks like these, bigger is better. Overkill as it may be, I’ve found that local farmers in New England who use retired telephone poles for their high-stress points have great long-term success; especially at corners, bar-ways and gate openings. If you’re in the market for telephone poles, look on your regional Craigslist.org, freecycle.org, or talk to linemen you may know.

If you don’t have any luck procuring retired phone poles, then my alternative favorite is 6×6 pressure-treated landscape timbers. These can be found at your local big box store for a reasonable cost, and are widely available. In a pinch, you could select, cut, and shape a tree from your property to use as a post, but that could result in premature replacement because of relatively quick rotting. Additionally, this method takes time, tools, and effort you may not have.

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Frost Heave Prevention

Ever notice that telephone poles are thicker at the bottom? This is the natural shape of the trees they make them from, but the tapered shape also helps keep them seated in the face of frost heaving. Posts that are improperly buried can work their way out of the ground, but if we sink our posts with the fat end down, the tapered shape will actually help keep the post from rising over the years of frost-thaw cycling. Cedar poles have this shape too, so be sure to bury them correctly with the thicker end down.

Frost heaving occurs when the water in the soil freezes and expands. The pressure caused by this expansion forces soil upward and anything within it, including your posts. When posts are set correctly, the tapered shape makes it harder for them to be pushed out. Think of it like a watermelon seed between your thumb and pointer finger. If you squeeze your fingers the seed goes flying away from you or toward your palm, depending on which side of the middle you squeeze. The same principle is in play here.

When we bury the fat end of a post down, the frost heave pressure will push the post further into the ground. This downward pressure locks it against the frozen ground below, and your post stays put. Conversely, putting the skinny end of your tapered pole into the ground lets the frost heave push it right out of the ground. You don’t want all your estate fencing popping out of the ground after all the time and effort you spent putting it there, so make sure you bury your posts fat end down.   

Anchoring Posts

In northern climates with significant heaving or with posts that are supporting a significant weight, consider cementing them into place. Wood that contacts cement is notorious for rotting quickly, so when you’re anchoring your posts in cement, be sure to follow some basic rules.

  • Be sure to add gravel to the bottom of your hole for water drainage. Fence post depth, size, and anchoring systems can make or break your fence line.
  • Make your cement anchor is tall enough to end above ground, preferably in a tapered shape to shed off groundwater.
  • Use rot-resistant posts like cedar, pressure-treated timber or good-quality steel if your application warrants it.
  • When pouring a proper post anchor, do your best to make it bell-shaped to take advantage of the frost heaving pressures to keep your post seated. Water will rot your post eventually, the grade of metal or wood you use simply dictates how long it takes to rot.

Water will rot your post eventually, but you can prolong the inevitable by having your cement anchor peak above the ground to reduce the amount of ground water that seeps between your post and concrete. Having a gravel base for water to escape into will also significantly extend the life of your post.

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Fence Post Depth

Unlike a footing or poles for a pole barn, fence posts don’t typically extend past the frost line. The rule of thumb for setting your fence post depth is this; not less than one-third the overall length of the pole and not more than half the overall length. More is actually OK, it’s just overkill. Setting your fence post depth to one-third the overall length is the bare minimum since you run the risk of it giving way to lateral pressure, such as livestock rubbing against it, heavy winds, or snow drifts.

This is not an either/or rule. Depending on how much post you need above grade will largely dictate your fence post depth, and as long as its depth is somewhere between one-third to one-half the overall length, you should be just fine.

Take into account how much post you need to have above grade when purchasing fence posts. As an example, if you want four-foot tall posts you have a choice of buying a nominal overall length post of six, seven or eight feet long. Most people like to have fence post tops level with each other, but the grade of the land may not cooperate. If you run the minimum length of six feet, you won’t have wiggle room to make that happen, but if you use a seven- foot or eight-foot-long post, you’ll have plenty of length to compensate. To achieve that professional look of level post tops, either painstakingly adjust your fence post depth to fit your level line, or set all your posts to the same fence post depth, snap a level line and cut the excess post to length once they’re set in place.

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