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How to Install Concrete Fence Posts (Step-by-Step Guide)
How to Install Concrete Fence Posts
Installing concrete fence posts is one of the best ways to build a strong, long-lasting fence. Unlike timber, concrete posts won’t rot, warp or weaken over time. As a result, they are a popular choice for both tradespeople and serious DIY jobs.
In this guide, we’ll show you exactly how to install concrete fence posts step by step. We’ll also cover the tools you need, common mistakes to avoid, and the fixings required for different fence types.
Why Use Concrete Fence Posts?
Concrete posts offer several advantages over timber:
- Strong and durable
- Resistant to rot and moisture
- Withstand high winds
- Low maintenance
- Ideal for long-term installations
In addition, slotted concrete posts make installation quicker, as fence panels simply drop into place.
Types of Concrete Fence Posts
Before you start, it’s important to choose the right type of post:
Intermediate posts
Used between panels in a straight run.
Corner posts
Designed for 90° turns in your fence line.
End posts
Used at the start or end of a fence run.
Pro tip:
Always plan your layout before digging to avoid repositioning posts later.
Tools & Materials You’ll Need
Tools:
- Post hole digger or spade
- Spirit level or post level
- Tape measure
- String line and pegs
- Lump hammer
Materials:
- Concrete fence posts
- Gravel boards
- Postcrete or concrete mix
- Drainage gravel
Fixings & Brackets:
- Arris rail support brackets (for closeboard fencing)
- Arris rail mortice brackets (for morticed concrete posts)
- Arris rail brackets
You can also improve accuracy using a post level, especially when working alone.
Step-by-Step: How to Install Concrete Fence Posts
Step 1 – Mark Out Your Fence Line
Start by setting up a tight string line between two pegs. This gives you a straight reference for your fence. Next, measure and mark where each post will go. Most fence panels are 1.8m wide, so spacing should match this.Pro tip:
Check for slopes before marking out. Uneven ground can affect spacing and post height.
Step 2 – Dig the Post Holes
Dig each hole to a minimum depth of 600mm (2ft). The width should be around three times the width of the post. Add 50–100mm of gravel at the bottom to improve drainage.Trade tip:
If you’re working in clay soil, dig slightly deeper to prevent water build-up weakening the post.
Step 3 – Position & Level the Post
Place the concrete post into the hole. Then check it is perfectly vertical using a spirit level or post level.
If needed, brace the post with timber to hold it steady.
This is where using a post level really helps with accuracy.
Pro tip:
Always check two sides of the post. One side alone is not enough.
Step 4 – Add Postcrete or Concrete
Pour your postcrete into the hole around the post. Then add water as directed.
Fill to just above ground level.
Important tip:
Slope the top of the concrete away from the post. This prevents water sitting at the base.
Step 5 – Align the Fence
Before the concrete sets, check alignment using your string line.
Adjust each post as needed to keep everything straight.
Trade tip:
Take your time here. One misaligned post will affect the entire fence.
Step 6 – Install Gravel Boards and Fence Panels
Start by fitting the gravel boards. These protect your fence from ground moisture.
Then slot fence panels into place.
For closeboard fencing, you’ll need fixings such as:
This method is commonly used for concrete post fencing systems and makes installation quicker and more secure.
Pro tip:
Rub a candle or wax inside the grooves. This makes panels much easier to slide in.
Step 7 – Allow the Concrete to Set
Postcrete sets quickly, usually within 5–10 minutes. However, you should leave it for at least 24 hours before adding weight or stress.
Avoid working in strong winds during this stage.
When Do You Need Fence Brackets?
If you’re installing closeboard fencing or rails, you’ll need additional fixings.
These include:
- Arris rail support brackets
- Mortice brackets
- Rail brackets in various sizes
These provide extra strength and keep your fence secure over time.
How Much Postcrete Do You Need?
As a general guide:
- Standard fence post: 1 to 1.5 bags
- Larger holes: up to 2 bags
- Deeper posts: may require more
Always check hole size and depth before estimating.
Common Mistakes to Avoid
- Not digging deep enough
- Skipping drainage gravel
- Not checking levels properly
- Misaligned posts
- Not using enough concrete
Fence & Gate Hardware
Concrete vs Timber Fence Posts
| Feature | Concrete Posts | Timber Posts |
|---|---|---|
| Lifespan | Very long | Can rot over time |
| Maintenance | Low | Higher |
| Strength | High | Moderate |
| Installation | Heavier / harder | Easier |
FAQs
How deep should concrete fence posts be?
At least 600mm deep, or deeper for taller fences.
How long does postcrete take to set?
Initial set takes 5–10 minutes. Full strength develops over 24 hours.
Do I need gravel at the bottom?
Yes. It improves drainage and prevents water damage.
Can I install fence posts without concrete?
You can, but concrete provides much better strength and durability.
What size concrete fence posts do I need?
Most standard fence panels are 6ft wide, so posts are typically spaced at 1.8m centres. Always check panel size before installing.
