If you’re installing a fence, one of the first questions that pops up for most people is how deep should the fence posts be? This makes sense, as fence posts are like the skeleton that holds the fence together.
If they aren’t dug deep enough, the fence won’t be properly supported and could actually fall over in a strong wind. The depth of the fence post hole, along with its diameter, are both key factors in the strength of your fence posts.
If you’re looking for a quick and dirty answer, fence post holes should be dug between 1/3 and 1/2 the length of the fence post. So, for an 8-foot fence post, the hole should be between 2 2/3 feet and 4 feet deep.
Let’s take a closer look at how deep fence posts should be, as well as several related topics that come up when digging fence post holes.
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Fence Post Depth Explained
When it comes to digging fence post holes, there is actually a lot to consider.
First off, you’ll want to keep in mind the height of your fence before digging. You’ll need to plan out the fence installation beforehand, which means considering any required permits as well as the location of any utility lines and your fence post height.
The fence height is key as it will determine the right height for both your fence posts and the depth of your post holes. For instance, if you’re fence is 6 feet tall, and you’re going to use 8-foot fence posts, then your holes will need to be 2 feet deep. If you want increased strength, then you’ll need to go with 10-foot fence posts, which will allow you to dig your post holes 4 feet deep.
While this may not be a requirement for your area, you may need to consider your local building codes when planning out your fence installation.
Another thing to consider is that you’ll want to add about 6-inches at the bottom of your fence post hole to pour gravel. This will give your post hole good drainage, and provide a stable surface to pour the concrete into.
Factors Influencing Fence Post Depth
When digging fence post holes, make sure to consider the type of soil as well as how windy and stormy your area is.
Areas with high winds and frequent storms mean your fence is more likely to be tipped over in heavy winds. In these environments, opt for deeper fence post holes to reinforce the fence’s strength.
If you live in an area with sandy soil, then you’ll want to go with increased hole depth. On the other hand, if your area has tough, clay-like soil, then you can afford shallower post holes.
What Diameter Fence Post Holes Should I Dig?
When you’re planning a fence post installation, you’ll need to consider the diameter of your post hole as well as its depth. The post hole diameter will help determine the overall fence’s strength.
The general rule of thumb for fence post holes is three times the diameter of your fence post. This means that for a 4×4 fence post, you’ll want to dig the post hole 12-inches in diameter.
What to Use to Fill your Post Holes?
The most common material to fill your post holes with is fast-setting concrete like Quikrete. Quikrete’s fast-setting mix is the ideal concrete mix for this task as it doesn’t require mixing – meaning you can pour is directly into the post hole and then add water. It also dries in just a few hours and cures enough to start installing the fence panels in just 24 hours.
You can also use a standard concrete mix to pour in your post holes, but this will take longer to dry and cure.
While it’s not the ideal solution for every situation, you can also fill a fence post hole without concrete. In this scenario, you’ll use loose gravel to fill the hole, and then tamp it down to compact the gravel around the post.
This method has the advantage of being easy to repair in case a storm pushes your fence over and offers a similar level of security to concrete when done properly.
