Postcrete is an easier way to set fence posts. No longer do you need to measure out your cement, sand and aggregate and then mix it all together to make concrete. Instead, you can shove a premixed bag of postcrete into a hole, add some water and you’re done. But how many bags should you use? Is there an optimum amount you should be using? Let’s have a look and find out.
So, how many bags to use?
This is going to be answered with a classic, it depends. The amount of postcrete you need to use per hole depends on the size of the hole. The size of the hole depends on the size of your post and the size of your post depends on the size of your fence.
Let’s start with the bigger end of the scale. If you are setting large 2.4m posts for a 1.8 fence then you will want to be using two bags per hole.
These larger fences are obviously going to get affected by the wind a lot more than a smaller ones. For this reason, you want to make sure your posts are really securely in the ground to prevent them from simply blowing over.
For your average fence, I would recommend using at least 1 and a half or preferably two bags of postcrete per post. The extra cost of the postcrete will be more than made up for with a strong fence that is less likely to blow over and need repairs.
As well as the size of the fence, the position and style of the fence also matter. If the fence is well exposed then you will need bigger, deeper holes which in turn will require more postcrete.
Also if your fence is solid it will need stronger posts as it will act more like a wind sail. If it has holes or trellising that allow the wind to pass through then you might be able to get away with a bag a hole.
With small fences, you can just use a bag a post. This is also true for fences that have large gaps that will allow the wind to pass through without much force being applied to the fence itself.
This fence at my allotment was put up by the council. Originally the posts were just driven into the ground. This was fine until I put the green netting up, this catches the wind more than the original fence which means I have had to postcrete the posts in to help them stay upright.
The original fence barely caught the wind at all, which is why the posts could be driven into the ground. But now it catches more, so needs to be secured. Even still, a bag a post is enough to really secure this fence.
If your fence is larger than this, or if the panels are solid, then I would recommend using two bags per post. Do the job properly once and you won’t have to repair it anywhere near as often. And with the storms we have been getting recently I can guarantee there are a lot of people who are wishing right now that they’d built their fence a bit more securely at first.
How do you use postcrete?
I have a full guide on this here: How to use postcrete but I will also provide a quick breakdown for those of you in a hurry below.
Step 1 – Dig Your Hole
The obvious place to start is by digging your hole for your post.
Step 2 – Fill Your Hole One Third Full With Water
Now add some water to your hole. You want it roughly one-third full and with the water no longer draining away.
Step 3 – Place Your Post In The Hole
Now place your post into the hole, don’t worry about getting it perfectly straight just yet.
Step 4 – Add Postcrete
Now comes the time to add some postcrete, keep adding it until the postcrete comes just above the water level.
Step 5 – Aerate The Mixture
Use a long pole to mix up the postcrete a little. Just jab it up and down into the mix.
Now comes the time to get your post perfectly straight while the mix is still wet and moveable.
Step 7 – Keep the Post Straight As The Mix Sets
Now you need to keep the post perfectly straight while the postcrete mix sets. You can do this by either clamping or fixing it to a support structure or just holding it. Fixing it to a support structure is definitely the better way though.
That’s all there is to it, your post is now set. The postcrete will continue to harden over the next few hours so don’t knock the post as it will still be liable to move a little.
Postcrete vs Concrete, what’s the difference?
again I have a full article on this, find it here: Postcrete vs Concrete
So what exactly is the difference between these two? Well the most obvious, and the one you will notice straight away, is how you use the two. Postcrete is much easier to use than concrete, no mixing is required, just chuck it in your post hole add some water and away you go.
No mixing is required with postcrete
When using postcrete all you have to do is add water to your post hole and then chuck the postcrete in. That’s it, no mixing at all. The postcrete will then proceed to set over 15-20 minutes from my experience.
Contrast this with concrete which you have to pre-mix and mix well before putting it anywhere and you can see that postcrete is much easier to use, when setting posts at least.