A fence is only as strong as its posts. When building a fence, the posts are the foundation, so it’s essential to think about each fence post’s size, spacing, and depth as you plan your space. As a general rule, fence posts should be 8 to 12 feet apart and placed at least two feet deep or one-third of the total post height, with a base of soil, gravel, or concrete. Let’s take a closer look at how to set fence posts for a strong, sturdy fence.
Setting fence posts requires some digging. You’ll want to place each post at a depth of at least two feet. However, taller fences may require more stability provided by deeper posts. Gate posts and corner posts also bear the brunt of the workload and may require extra stability.
Mark Out the Area to be Fenced
For starters, you’ll need to know where you’ll be placing fencing and how large the total area is. You’ll also need an idea of how tall the fence needs to be and what purpose the fence will serve. But we’ll guess that if you’re ready to set fence posts, you already know.
Take this one step further and specifically mark each post-placement. If you’re using t-posts, plan for no more than an 8-foot distance between posts. Depending on the fencing material, you can generally get away with longer distances of up to 15 or 20 feet for wildlife fencing. And if you’re using sturdy wood posts for horses or other livestock, stick with the general rule of 8 to 12 feet apart.
Don’t forget to plan for the width of gates, placing posts on either side and adding a little more stability on the corners with a closer placement or stronger bracing.
Check for Wires and Utilities
Setting fence posts requires digging. You’ll use a post-hole digger or t-post driver to set posts at least two feet into the ground. Don’t forget to check for wires, plumbing, and other utilities that might interfere with post-placement. Most utility companies will come to mark their lines for free if you call before you dig.
Get the Right Tools
Digging post holes can be hard work. Before you begin, plan ahead and gather the right tools for the job. If you’re setting wood fence posts, opt for a post-hole digger mounted to a tractor to make the job a lot easier. And if you’re using t-posts for your wire fence, invest in a post-driver to easily get the correct depth. We also recommend keeping a few shovels on hand in case you need to clean up any holes or add depth by hand.
Installing Fence Posts
When the day comes to start installing your fence posts, plan a whole day or more to get the job done. It’s hard work, and you’ll want to enlist some help. If you’re using t-posts, digging the holes and installing the posts are all done in one shot. These steel posts do not require any drainage or added stability because they do not rot, and they feature a t-shaped anchor for stability. However, wood posts require a bit more work.
Check the Depth
The minimum depth for a wood post is two feet. That doesn’t mean that your fence is good at two feet. First, consider adding gravel for drainage and add at least six inches for that drainage. Then, consider the height of your fence and the animals it will contain or restrict. The posts should be set between three and four feet deep for large livestock like horses or cattle, plus drainage.
Add a Drainage Layer
Use gravel or crushed rock to add some space for drainage. Allowing water to move away from the posts underground will help prevent rot and keep your fence sturdy for years to come. This is where many first-timers get confused. Perhaps you’re considering footing your fence posts in concrete, but is it really necessary?
Setting Posts in Holes
A quick bit of concrete is an effective way to stabilize a post underground, but it’s probably an unnecessary step unless you’re building 18-foot-tall fences. For typical agricultural applications, the only posts that need a concrete footing are gate posts and possibly corner posts for additional bracing. Remember that these two areas take the most stress on your fence line. Filling the holes with the dirt you previously removed and tamping it firm should be sufficient for all other posts.
You’ll find various products on the market for setting fence posts. Each has an appropriate use, but not every product is suitable for every type of fence or type of soil. You can use gravel to create a drainage layer for wood posts placed in soil. You can also use gravel to add drainage around the entire depth of the post in areas that have more clay than topsoil. Or as a mix-in for sandy soil.
Some manufacturers also sell polymers like post-setting foam, which are designed to provide an alternative to concrete. While concrete is the traditional stabilizer, it gets a bad rep for polluting the soil. While polymer (foam) fillers are made from plastics, these manufacturers insist they are a more environmentally friendly alternative.
The Bottom Line
Properly setting fence posts is essential to the stability and durability of your fence line. As a general rule, keep in mind that one-third of the post height should be set underground. And depending on the material and soil, you may want to add a drainage layer with gravel, stability with foam or concrete, or diligent soil tamping to ensure secure placement. Additionally, gate posts and corner posts require a little more stability. However, if you follow these guidelines, you can construct a sturdy fence to keep wildlife out or livestock in.