Welcome to Back Garden & Beyond.com! Today, we’ll be discussing one of the most important aspects of installing a fence: how to dig a post hole.
Digging a post hole is an important part of any fencing project, no matter how big or small. It’s the foundation of your fence, and it needs to be done properly for the fence to last. With that in mind, let’s dive into the steps of How to dig a post hole.
First, you’ll need to decide where you want to Install your new fence posts.
The main things to consider when marking the location of your fence posts are
- Start and end posts – You will need a post at the start and end points of your fence line.
- Post centers – The style of the fence you are installing will determine the distance between posts.
- Allow extra posts – for any major changes in direction or ground levels.
Now it’s time to set up a string line from the start of your fence line to the end point. Using a wooden stake or line marking spray, mark the location of the starter post. Now mark the rest of your post holes at the relevant post centers until you reach the location of the end post. We recommend reducing the post centers when following changing ground levels.
When digging fence post holes, safety is always paramount & now is a good time to check any available service drawings or ask neighbours about any known underground utilities and services. Its also a good idea to use a CAT (cable avoidance tool) to locate any underground electric cables, these can be easily hired from most tool hire shops.
How wide and deep does your post hole need to be?
The main things to consider when deciding the depth of your fence posts are
- Post width – we recommend your post holes are 3x bigger than the post width, for example a 100mm square post will need a 300mm square hole.
- Fence height – your post hole depth will need to be 1 third of the the overall fence height, for example a 6ft fence will require the posts to be 2ft in the ground. Allow an extra 50 – 100mm for shingle under the post for extra drainage.
- Dig a square hole – A square hole holds the concrete surrounding a fence post a lot better than a round or tapering hole will.
- Ground conditions and substrate – If the ground is really soft or wet increase the size of your post holes.
It’s time to start digging!
Make a very labour intense task much easier with the use of a powered auger. An auger will drill into soft ground with no issues, but please be aware they can catch on large hard rocks that are buried. To avoid any injury an auger should be operated by two people.
We like to dig our holes with a fencers graft and post hole diggers. This allows us to stand upright and dig, minimizing bending over as much as possible.
Loosen the ground with the graft. With both hands firmly gripping the top of the fencing graft, force the spade end into the ground. Dig into the side of the hole and leaver into the center of the hole to loosen the soil. Scoop out any spoil with the post hole diggers, making sure not to put the spoil on the fence line.
We recommend scooping the spoil directly into a wheelbarrow or flexi bucket. This will speed up the clean up time as well as keeping your work environment tidy and safe.
If you come across hard ground, ie concrete, tarmac, old walls etc? You will need to hire a jackhammer breaker to help break up the ground before scooping into flexi buckets.
Now using a spirit level, install your posts both upright and plumb to the fence line. If needed brace your post in position and slowly fill the hole with concrete. We fill the hole slowly so we don’t knock the post off of the line. Fill the hole to the top, compacting the concrete as you fill. If you are using ready mixed bagged concrete like postcrete pour water into the hole first before adding the bagged concrete, leaving a little space for soil on top.