You don’t have to look far to find a fence with loose, sagging wire. Which is surprising, considering the job a fence does for any farm operation.
Got one of your own? Cast your eye down the fence line to the end post. Odds are it’s tilting, or slowly rising out of the ground.
The wire is rarely the problem. The strainer post assembly is. Get the assembly right and the fence holds tension for decades. Get it wrong and you’ll be back out there re-straining it every season. This guide covers the specs that matter, how to install a strainer post properly, and the mistakes that bring fences down.
THE PROBLEM
Why Fences Fail
When a fence fails, it comes down to one of three causes: structural failure, soil movement or post pull-out.
Structural failure means inferior materials, or an end assembly that was designed or built wrong. Soil movement means the ground doesn’t have the strength to carry the load of the fence, which is usually fixed with longer posts. And post pull-out means the post wasn’t set deep enough, or the stay wasn’t long enough.
All three end the same way, because the strainer post carries the whole fence. It cops both vertical and horizontal forces, and if it fails, the fence fails with it.
Think of a see-saw. When one kid is heavier than the other, the lighter kid goes straight to the top. Same with your strainer post. If the pull of the wire beats the pull of the ground, the post moves. A diagonal stay assembly cancels those forces out. It brings balance.
THE NUMBERS
Strainer Post Specs That Matter
Before you put anything in the ground, get these four numbers right.
| Spec | Recommendation | Why |
|---|---|---|
| Post size | 80NB (89mm O.D.) or 100NB (114mm O.D.) steel | Bigger diameter doesn’t mean better hold. Depth and installation method do the work. |
| Post depth | 1200mm minimum for a driven post; 950mm if concreted in | Depth drives holding power: a post at 1m has about double the load capacity of one at 750mm (30"). |
| Stay length | At least 2½ × fence height | A 1.2m (48") fence needs a stay at least 3m (10′) long. Too short and the post pulls out. |
| Stay position | Post clamp about two-thirds of the way up the post (approx. 900mm on a standard 1200mm fence) | Too flat or too steep and the stay acts as a fulcrum, levering the post out of the ground. |
STEP BY STEP
How To Install A Strainer Post Assembly
1.
Mark out your assembly points.
You need an end assembly wherever the fence starts, ends, changes direction, crosses a change in topography, or meets a gateway (one on each side of the gate).
2.
Drive the strainer post.
Drive it, don’t dig it. Driving causes the least disturbance to the soil, and the soil is what holds your fence up. Set the post at least 1200mm deep. A driven 80NB steel strainer will outperform a much larger timber post dropped in a hole and tamped in.
3.
Set up the stay and footplate.
Your stay needs to be at least 2½ times the fence height. Sit the footplate on top of the ground, unpinned, and lay the stay in the direction required. Don’t bury the footplate, don’t peg it. (More on why below.)
4.
Install the LokDown Lugs.
One lug on either side of the post, approximately 50–100mm below ground level. Start with the centre Tek screw, fit a half- or full-length picket into each lug, then backfill and compact the soil firmly around them.
5.
Position the tension cable.
Place the stainless steel cable loop over the post. Installing a corner assembly? Add the extra cable loops now.
6.
Fit the TWIST-TIGHT® connector.
Slide the disk onto the tongue and insert the tongue into the end of the stay, then tap it firmly into position. The Adapt-a-Fit tongue adjusts to suit different stay sizes.
7.
Fit the post clamp.
Position it about two-thirds of the way up the post, roughly 900mm on a standard 1200mm fence. Sit the tongue between the clamp tabs, insert the bolt and finger tighten.
8.
Connect the stay.
Lower the stay onto the footplate tongue and make sure it’s seated firmly before you tighten anything.
9.
Tension the system.
Tighten the eyebolt with the StayTight tube socket and an impact driver until the assembly is fully tensioned, holding the eyebolt so it doesn’t spin. Use the supplied anti-seize so the adjustment stays smooth for years to come.
10.
Fit the post cap.
Hammer it firmly onto the post. That’s the assembly done. Ready to strain your fence.
One last thing: a fence starts losing tension within 24 hours of going up, and keeps losing it from there. With an adjustable assembly you take up that slack in minutes, without cutting or re-tying a single wire. So strain up, come back the next day, and take out the slack.
MATERIALS
Steel vs Timber Strainer Posts
Plenty of good fences have been built on timber strainers, and if you’ve got access to quality timber, they’ll do a job. But here’s how the two stack up where it counts.
| Driven steel assembly | Timber assembly | |
|---|---|---|
| Installation | Driven. Minimal soil disturbance, maximum hold. | Dig, drop, backfill, tamp. The disturbed soil never holds like undisturbed ground. |
| Time | Under a quarter of the install time | The slow way. Costs less at the counter, costs more by knock-off. |
| Adjustment | Fully adjustable for the life of the fence | None. Once it’s in, it’s in. |
| Lifespan | Hot dipped galvanised steel. No rot, no white ants. | Depends on the timber, the soil and the weather. |
The biggest fencing oversight isn’t materials. It’s time. When a job gets priced up, the option with the smallest initial outlay usually wins, and that’s typically timber or welded steel. Then the install takes four times as long, and the “expensive” option suddenly looks like the bargain it was. Think about what else you could have done with that day.
THE RANGE
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QUICK ANSWERS
Strainer Post FAQs
Can’t find what you’re looking for? View all FAQs or get in touch.
Not as much as you’d think. A commonly held belief is that a fatter post holds better in the ground. It doesn’t. The depth of the post and the way it’s installed matter far more, which is why an 80NB or 100NB driven steel post beats a big timber post in a backfilled hole.
Yes. Without one, the weight of the fence ends up on the footplate. The tension cable transfers that weight to the base of the strainer post, where it’s needed most. That reduces the chance of the post lifting out of the ground, and with the weight off the footplate, it won’t sink either.
Think of an earthquake. Anything anchored to the ground in more than one place is in trouble. Whatever is allowed to move with the ground survives.
Same with a diagonal stay assembly. The only thing that should be fixed is the strainer post. Everything else should move with the conditions the fence is put through. The footplate “floats” because it sits on top of the ground, unpinned. Pinning it, burying it or restricting its movement defeats its purpose and puts the weight of the fence exactly where you don’t want it.
A stay set into the ground will fail over time, even with a backing plate, and it takes the fence with it. A floating footplate also needs no digging, which makes it a real time and back saver.
Within 24 hours of a fence going up, it starts losing tension, and it keeps losing it for the rest of its life. With an adjustable assembly you respond to changes in the fence line before they become a problem. StayTight assemblies give you that control through the tension cable and the post and stay connectors. You don’t get it with a traditional timber assembly, a welded steel assembly, or any assembly with its stay buried in the ground.
A fence line that’s cared for will give you decades of service. It makes sense to be the one in control of it, rather than letting nature dictate terms.
Wherever the fence changes direction, wherever the topography changes, and on both sides of every gateway.
THE GEAR
Need A Strainer Post Assembly?
Our StayTight end assemblies are among the most versatile and rust resistant on the market. Every component is hot dipped galvanised, every design is fully adjustable, and there’s no welding or digging on the job.
Set up your strainer post and full end assembly in under 15 minutes. Yep, you read that right. Available from over 900 stockists Australia wide.
Sorting out the rest of the fence line? Read our Farm Fence Post Spacing Guide next.
Products Mentioned in this Article
Drive-Tight® Hand-Driven End Assembly Kits
Our most popular, and fastest to install end assembly.
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Twist Tight Post & Stay Connectors
Heavy-duty galvanised Twist-Tight post and stay connectors.
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Fitting Kits
Our fitting kits are perfect for when you already have your own posts and stays.
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