When building your own fence, you will most certainly want to ensure that the fence is of the best possible quality and that it will stand up to whatever forces might possibly be thrown its way during its lifetime. While there are other ways in which your metal fence posts can be secured, concrete is the best option for ensuring the longevity of your fence.
The best concrete for metal fence posts is premix concrete such as Sakrete or Quikrete. Both options are able to set within 20 to 40 minutes and require no mixing. If you decide not to opt for premixed concrete, the best ratio is 1:2:4 (cement, sand, and aggregate, respectively).
There are several reasons why concrete is the essential choice when installing metal fence posts.
Best Concrete For Metal Fence Posts
Generally speaking, concrete is always best when mixed with a cement mixer. This is because the cement mixer ensures that the concrete is mixed evenly, ensuring an even distribution of the components, and therefore a resultant concrete that performs optimally.
When mixing your own concrete, the best mix to use is a ratio of 1:2:4. This means 1 part cement, 2 parts sand, and 4 parts aggregate. If you are unable to bring in a cement mixer for this project, or the cost is simply too prohibitive for the scale of the project, you can mix the concrete by hand.
It’s important when mixing concrete by hand to ensure that the mix is as even as possible before using the mixed concrete in your project. It’s also important to ensure that the concrete being used is at least 20mPa in terms of its strength.
If you are not mixing your own concrete, making use of premixed concrete such as Quikrete or Sakrete comes highly recommended. The reason for this is that despite having been mixed already in the correct proportions, this type of concrete can be poured directly into the hole while dry.
This simple method of use will save enormous amounts of time and labor. With premixed concrete such as this, you simply need to pour the dry powder into the hole before pouring in the correct amount of water. The concrete will then start to set within twenty to forty minutes, ensuring a quick and efficient installation process.
Whether opting for premixed concrete or one that you have mixed yourself, it’s best to wait until the day after pouring the concrete before attempting to build the fence. This will ensure that the concrete has set sufficiently.
While the concrete (especially the premix) may be able to set quickly and may allow you to begin construction within 4 to 6 hours after pouring, it will be best to allow the concrete sufficient time to cure before adding any external forces to it.
How Much Concrete Is Needed For Metal Fence Posts?
The amount of concrete needed for metal fence posts depends on the size of the hole to be filled. The size of the hole, in turn, is determined by the diameter and height of the fence posts to be used.
A general rule of thumb suggests that the depth of the hole for a fence post should be a minimum of 25% (but preferably a third) of the height of the entire post. The width of the hole should be three times the width of the post.
Resultantly, a fence post with a diameter of three inches would require a hole for its post that is around nine inches in diameter. The depth of the hole – if the post was around six feet tall – would need to be around two feet.
The table below is a quick guide of how much concrete you will need if math is not your strong suite(like me). It is on the conservative side so that you won’t come up short, but may have a little concrete left over in the bag.
| Depth | 6″ diameter | 9″ diameter | 12″diameter |
| 12″ | 1 | 2 | 2 |
| 14″ | 1 | 2 | 3 |
| 16″ | 1 | 2 | 3 |
| 18″ | 1 | 2 | 3 |
| 20″ | 1 | 2 | 4 |
| 22″ | 1 | 2 | 4 |
| 24″ | 1 | 3 | 4 |
| 26″ | 2 | 3 | 5 |
| 28″ | 2 | 3 | 5 |
| 30″ | 2 | 3 | 5 |
| 32″ | 2 | 3 | 5 |
| 34″ | 2 | 3 | 6 |
| 36″ | 2 | 4 | 6 |
The amount of concrete needed is calculated in terms of the number of fifty-pound bags that will be needed to fill the hole. For a three-inch post with a nine-inch diameter hole, you will need about one bag of concrete per foot of hole depth.
If you opt for a four-inch post, the hole will be twelve inches in diameter, and so you will need 2 bags of concrete per foot of hole depth. If the fence post you are using is six inches in diameter, the hole will be eighteen inches wide, and so you will need approximately four bags of concrete per foot of hole depth.
How To Set Metal Fence Posts In Concrete
While it is relatively easy for any DIY enthusiast to set fence posts in concrete, it will require a fair amount of patience as well as the correct tools to complete the job. For a more in depth explanation on how to set your fence posts, check out this article.
Firstly, you will need to dig a hole for every post that you plan to install. These holes should be dug according to the guidelines discussed earlier in this article. Next, insert the pole directly into the hole while ensuring that it is completely level in all directions.
It might be a good idea to coat the bottom of the post in epoxy paint up to 200mm from the bottom to ensure that the post is protected from moisture at its base.
Once the post is correctly in place (and held in place using temporary supports), pour the concrete mix into the hole, letting it fill up to two inches below the surface of the hole. Ensure that the post does not move while the concrete is being poured in, and leave it to cure.
Why Should Metal Fence Posts Be Set In Concrete?
Metal fence posts should be set in concrete in order to ensure that they do not move at all during their lifetime. It is important that the fence posts are secured into place without the potential for movement. This will ensure that they are able to support the fence (which applies significant lateral loads to the posts) as well as withstand any loads that are applied to the fence itself.
An insufficiently anchored fence post (i.e., one that is not set in concrete) will ultimately cause the post to move, subsequently causing the fence to fail if any load is applied to it whatsoever.
Conclusion
Whether you opt to mix your own concrete or decide to make use of one of the ready mix options, by ensuring you use the right concrete for your fence posts, you will be assured of a strong and long-lasting fence system.