The sturdiness of posts matters the most when installing a fence, as they have to bear all the tension and lift the weight of the whole fence. The stronger a fence post is installed, the more weight it will bear for a longer time. Two common methods to install fence posts are setting them in concrete by digging holes or using fence post spikes. Both fence post-installation processes, concrete and post spikes, have pros and cons, which we’ll discuss below.
Fence Post Spikes Vs. Concrete
The most traditional and sturdier way to install fence posts for permanent and large-area fencing is to set them in concrete. However, it will cause a lot of hassle by digging fence post holes, and the concrete will also increase the budget.
The other standard tool for installing fence posts is the fence post spikes. In addition to the simplified installation process, fence post spikes are removable. However, note that the spike(anchor) is thin and may shift or lean due to heavy winds, weight, or moist coil conditions or may bend while installation if there is a hard rock underneath. Therefore, they are less sturdier as posts set in concrete.
Below we’ll compare each aspect of both methods of fence post installation.
1: Strength
Concrete is a more robust option for long-lasting fences, especially when more sturdiness is required, such as farm fences that bear much weight and pressure. Concrete provides the necessary strength and durability to ensure that the fence remains stable and secure for many years, even under heavy loads and challenging conditions.
Fence post spikes, typically made of metal, do not have a specific PSI rating like concrete. Their strength depends mainly on the quality of the metal, the design of the spike, and the soil conditions where they are installed. While they offer a practical and easy installation method, fence post spikes generally do not provide the same structural integrity or load-bearing capacity as concrete. As a result, they are best suited for lighter fencing applications or temporary structures, where maximum stability and load-bearing capacity are not as critical.
Two types of concrete are commonly available for fencing post installation: normal concrete and fast-setting concrete. Normal concrete typically takes 24-48 hours for initial setting and reaches its full strength in around 28 days. It usually achieves a PSI of 4,000 to 5,000, making it an excellent choice for heavy-duty applications where maximum strength is essential.
On the other hand, fast-setting concrete sets within an hour (ideally usable after 3-4 hours) and reaches a strength of up to 70% in around 24 hours, with full strength developing in about 3-4 weeks. However, fast-setting concrete may not achieve the same level of strength as regular concrete, with a PSI ranging from 3,000 to 4,000. This makes it ideal for projects where time is a constraint, such as setting fence posts and mailboxes or making small repairs, where quick setting is more critical than maximum strength.
2: Stability
Concrete provides superior stability for fence posts, making them less likely to shift or lean for longer. Once the concrete sets, it forms a solid anchor in the ground, capable of withstanding heavy fence loads and harsh environments like strong winds, freeze-thaw cycles, and soil movement. It means that fence posts installed adequately in concrete can remain upright and secure for many years, often lasting 10-15 years or more before showing any signs of bending or leaning.
The solid support the concrete offers significantly slows the shifting process, making it an ideal choice for long-term, heavy-duty fencing applications where maximum stability is crucial. However, note that fence posts set in concrete are more prone to rotting quickly as they face more moisture due to rain or water accumulation near the post base.
On the other hand, fence post spikes offer a convenient and quicker installation method. Still, they generally provide less stability compared to concrete. Since spikes are driven into the soil without solid support like concrete, they are more susceptible to shifting, especially in loose or unstable soils. This can lead to leaning or tilting over time, particularly in areas with heavy winds or fluctuating soil conditions.
Posts set in spikes typically have a shorter lifespan before they start to lean, with bending or leaning often occurring within 2-5 years, depending on the fence load and environmental factors. In areas with challenging conditions, this learning might happen even sooner, sometimes within 1-2 years.
However, despite their moderate stability, the ease of installation and ability to protect the post from rot can still make spikes a viable option for lighter fencing needs.
3: Cost
Fence posts set in concrete and post spikes vary the installation cost. As per the general rules, the post hole’s diameter should be three times the width of the fence post. For example, if the post has a width of 4 inches, the post hole diameter should be three times 12 inches. Also, it’s recommended to set one-third of the post under the ground. So, two feet of a 6-foot-long post should be driven under the ground.
According to the concrete calculators, ideally, you’ll need around five bags of 50 LB concrete for a 4-inch-wide fence post (it’ll have a 12-inch hole diameter) and two feet deep.
You can use any of these calculators to calculate how much concrete will be needed for the entire project.
- https://www.cementaustralia.com.au/calculators/posts
- https://www.hooverfence.com/calculators/concrete
- https://www.quikrete.com/calculator/main.asp
If you have a 4-inch fence post, you’ll need 3-4 bags of 50 lb concrete for each post. Each pack costs around 5-6$, so it’ll cost you around 15-20$ per post.
However, fence post spikes cost around $13$ each. Another benefit of a fence post spike is that it holds the post above the ground. As the post doesn’t touch the soil, it doesn’t rot. So, whether the post spike leans quicker than a concrete fence post, it’ll keep the fence post surviving for longer.
4: Ease of Installation
If you want to set fence posts in concrete, much more effort will be required. First of all, you’ll have to dig fence post holes. You can dig fence post holes with manual tools like manual fence post hole digger tools, but they will take a lot more effort and time, and it is only recommended if you’ve to install a few fence posts.
However, for many fence posts, you should use an auger drill. After digging holes, you’ll have to mix the concrete or directly pour it into the hole, add water, and then mix. After that, you’ll have to wait for the concrete to fix and the same procedure has to be followed for every post. Moreover, you will need someone else to support you throughout the process.
However, just using a sledgehammer, you can drive a fence post spike on your own. The whole process takes merely five minutes per post.
Conclusion
Ultimately, deciding between setting fence posts in concrete or using fence post spikes depends on your specific needs and circumstances. Concrete offers better strength, making it ideal for heavy-duty fence applications despite the higher cost and labor.
On the other hand, fence post spikes provide a quicker installation and are more affordable, with the added benefit of protecting posts from rot. However, they may not offer the same level of stability over time. Understanding the demands of your project, including factors like soil conditions and required durability, will guide you to the best option for your fencing needs.
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