So you're thinking of erecting your own farm fence? A question we often get asked is:
How far should I space my posts apart?
Unfortunately, there is not hard and fast rule. Many different factors impact fence post spacing.
In this guide, we walk you through what you need to consider when spacing your fence posts, and what you can do to ensure a long-lasting and robust fence.
We have also given a number of examples to help you decided the best post spacing for your farm fence.
Firstly, it is essential to understand that there are two different types of farm posts. These are your fence strainer posts and your star pickets.
Strainer posts are designed to keep your wire fence tight and upright. The purpose of a strainer is to create an anchor point for the wires. Where anything changes, your wires need to be anchored so they stay the same distance and the same strain.
Pickets are used to guide the line of wires and to provide additional support.
With both strainer posts and picket, many factors will impact the distance between your fence posts. These including:
However, because strainer posts and pickets have different roles, you need to think about them differently when deciding how far to space them.
If you have a large number of wires, for example, 9 to 12, you will need as much support as possible. Your pickets will need to be closer together to support that extra weight.
If you have large stock, such as cows, you will need to have your pickets spaced closer together to withstand the tension of the animals against your fence. Barbed wire can help as a deterant for your cattle, but you still want to have that added strength.
If you have smaller stock like sheep or goats, you will be able to space your pickets further apart.
Whether your land is undulating or flat will impact the space between pickets. If you have a flat surface, you will be able to have more space between support pickets. If you are fencing in a hilly area, you will likely need more pickets so your fence follows the contours of the land. More on this below.
While the type of livestock will impact how far to space your pickets, it doesn't really affect your strainers. If you use a strong steel strainer posts of 80NB (89mm O.D) or larger, the post will be strong enough to support the fence. It won't matter if you have cows or chickens.
With any significant topography change, you should use a strainer.
If your fence dips down into a gully, you should have an inline strainer post at the bottom of the gully. Due to the strain of the fence wire, if you had a star picket, it would be pulled straight out. A strainer post will be able to stay tight in the gully.
This also applies to star pickets at the top of a hill. Use a inline strainer post at the top of the hill. This will ensure that your post doesn't get pushed into the ground due to the force of the strained wire.
If you are setting up a fence on a dead flat plain and going in a straight line with no hills or dips, you can easily get hundreds of meters between strainer posts.
In most cases, particularly for heavier duty fences, any change in direction will require a strainer post.
The pressure of the strained wire will cause a picket to be pushed/bend to the side. A strainer post can withstand the pressure and remain upright.
For significant changes in direction, the use of a stay can be used to ensure that the strainer post remains upright, particularly for highly-strung fences.
If you have a lower number of wire, for example, 3 to 4, or an electric fence, you may be able to get away with using star pickets for minor changes in topography or direction. However, for heavy-duty fences, you will want to make sure your fence is secure and tight by using a strainer post.
You will want a strainer post end assembly on each side of a gateway.
The thicker the wall is, the stronger the strainer post. This means you can have them further apart, and they will still manage to keep your fence tight and upright.
We recommend steel strainer posts of 80NB (89mm O.D) or 100NB (114mm O.D). Using less than 80NB will effect the strength of your fence and you will need to place them closer together. Resulting in more components and expense.
Here are some example situations you might be in and what you could potentially do.
These examples should give you an indicator to the different spacing you will need for different circumstances.
When it comes to ground conditions, depth is more important than the number of posts you have. In black soil/clay country, you will need to ensure that the post hits rock bottom to ensure it doesn't move. This means you will need a longer strainer post.
If you are erecting a fence in sandy conditions, again depth is more important than more strainers.
Rocky soils while being difficult to drive posts and pickets in, have an advantage. The rocks give added support to the fence posts, increasing the overall strength.
Plan out your fence by determining where you strainer posts will need to go. Start with the corners and where you want to place your gates. Assess where there will be any changes in direction and topography.
Can you kill two birds with one stone by putting your gate post where you want to change direction?
Mark out key areas: the end of your fence, any corners, gateways, or changes in topography. That's where you put your strainers.
Inline strainer posts should be included after every 5th picket to ensure a strong fence. (Potentially after every 3rd or 4th picket if you have rowdy cattle!)
For example, a farmer has 300 metres of fencing on flat terrain to put up. The farmer has decided to put a post every 5 metres. This farmer will have to put an inline strainer post every 30 metres so they can put a picket every 5 metres in between.
Evenly spacing out your pickets between your strainer posts provides even strength and support throughout your fence. And it looks better too!
Once your fence is entirely in (wires strained up) it is incredibly frustrating and time consuming to make changes. It is always easier to knock in another strainer post when there is no wire or strain.
Getting a new post in when your fence is all wired up is sure to cause headaches. Re-Configuration is a nightmare, so do it once and do it right.
For property boundary fences, don't forget to consider what your neighbor has. If they have Brahman's and you space your posts for a light duty three wire boundary fence, you are going to have a lot of headaches in the future.
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