Securing concrete fence posts properly is a crucial first step when installing a new fence or reinforcing an existing one in the UK. Concrete posts provide a sturdy foundation to attach fence panels or wire, keeping animals securely contained and preventing intruders from easily gaining access to your property.
However, if concrete posts are not set deeply and securely enough, they can easily become loose or lopsided over time due to factors like soil erosion, freezing and expansion of the ground, or force applied from animals or people leaning against the fence. This causes the posts to tilt and the fence panels attached to them to sag or detach, requiring expensive repairs. Consulting with professionals such as Aldershot fencing can ensure that concrete posts are installed to the appropriate depth and securely anchored, minimizing the risk of structural issues and costly repairs down the line.
Types of Concrete Fence Posts
Concrete fence posts are available in standard and slotted varieties to suit different installation requirements, terrain, and types of fencing.
Standard Concrete Fence Posts
Due to their simple shape, ease of installation, and lower cost, standard posts work well for most agricultural or residential privacy fencing needs where terrain is mostly flat and soil conditions are relatively normal.
Slotted Concrete Fence Posts
The slots make alignment and attachment of fencing components easier. These posts are ideal for uneven or sloping terrain, timber fencing, or installations requiring metal post braces spanning multiple posts for stability. Their lighter design also helps reduce strain when moving and transporting.
Now that you understand the differences between standard and slotted concrete fence posts, let’s go over the essential tools and materials you’ll need to securely install them.
Essential Tools and Materials
Securing fence posts properly requires having the right equipment and materials on hand before starting. Gather the following items:
Tools
- Post hole digger – Essential for excavating neat, cylindrical holes to the appropriate depth
- Power auger (optional) – Attaches to a petrol/electric drill for digging holes in tough soil
- Wheelbarrow – For transporting and mixing concrete
- Garden rake & spade – For smoothing and spreading soil displaced from holes
- Sledgehammer – To drive posts into the earth and packing soil and gravel tightly
- Spirit level – Verifies posts are plumb vertically and not tilting
- Measuring tape – Checks spacing between posts and hole depth
- String line – Helps align posts in a straight line
- Stakes & temporary braces – Holds posts in place while concrete cures
Materials
- Concrete mix – Pre-blended is easiest; alternately mix sand, gravel & cement
- Gravel – Creates drainage at the base of the post holes
- Vermin mesh (optional) – Metal mesh sleeve prevents rodent burrowing next to posts
- Post caps – Protect tops of posts from water damage and decay
- Steel rebar – Reinforces strength; use stakes for slotted posts instead
- Temporary wooden braces – Brace two sides of posts until concrete set
Step-by-Step Guide to Secure Concrete Fence Posts
Preparing the Site
First, survey where you’ll be digging the holes to identify any buried utilities, obstacles like tree roots/large rocks, and changing elevation that must be accounted for.
Mark the approximate spots for the post holes with spray paint or colored flags. The easiest way to ensure proper spacing is by staking a string line between endpoints and using this visual guide when digging.
When determining exact position of each post and gap between them, follow this spacing guideline based on common UK fence heights:
- Less than 1 metre (3 ft) – 1.5 – 1.8 metres (5-6 ft) between posts
- 1 – 1.5 metres (3-5 ft) – 1.8 – 3 metres (6-10 ft) between posts
- Over 1.5 metres (5 ft) – 2.5 – 3 metres (8-10 ft) between posts
Leave slightly wider gaps where slope increases so fence panels follow the terrain rather than creating low and high points between posts.
With the string line set and post locations marked according to appropriate spacing, shift soil and turf to access bare earth for digging the holes.
Digging and Setting the Post Holes
Now comes the elbow grease! Use your round nose post hole digger for a clean cylindrical hole at each spot, angling the blades inward around the sides as you dig deeper to maintain shape.
Follow these guidelines to determine the correct depth and diameter when excavating each hole:
- Total Depth – Hole should extend 60 – 75cm (2-2.5 ft) below ground level; deeper in soft/wet soil
- Upper Diameter – Approximately double the width of the post to allow room for backfill tamping
- Lower Diameter – Around 10cm (4 inches) wider than post (ex: 20cm post needs 30cm hole diameter)
Once you reach the appropriate depth, use a rake, spade or paddle to scrape and loosen compacted soil from the bottom and sides of each hole so water can still drain.
Next, add a 5-10cm (2-4 inch) base layer of gravel in the bottom before setting the post to promote drainage moisture away from the buried section.
Slide the post into position in the center of the hole, using a spirit level on two adjacent sides to verify it’s plumb vertically. Place stakes or braces extending above ground level on either side of the post to hold it straight while pouring concrete.
Mixing and Pouring Concrete
For easiest results, use premixed dry concrete and blend it with water in a wheelbarrow using shovels or a cement mixer paddle. Follow the manufacturer’s directions for mixing ratios. Generally a drier, thicker consistency works best to keep the concrete from becoming runny as it’s poured.
Once mixed, carefully pour concrete into the hole around the post in layers, tamping with the shovel handle after each layer to eliminate air pockets. Fill until the concrete is 5-8cm (2-3 inches) below ground level.
While wet, slope the top surface to angle away from the post, preventing water pooling at the base once cured. Insert a section of rebar or support spike extending from the concrete bottom up through the center of the post for reinforcement.
Finish by temporarily screwing braces into adjacent sides of the post to hold it plumb until the concrete fully hardens.
Installing the Concrete Fence Posts
Brace each post from opposite sides with angled supports screwed into the wood frame. This prevents the post from bending or twisting while the concrete slowly cures over the next 3-5 days.
Once concrete has completely hardened, carefully backfill the holes with soil and compact thoroughly. Mound remaining soil in a slope away from posts to improve drainage.
Monitor posts supports during this period when the concrete has solidified but soil settling continues around the posts over the following weeks. Remove temporary braces once posts feel firmly set in stable positions. They are now ready for installing fence panels!
FAQ
How deep should I dig the post holes?
General guidelines are:
- 60cm (2 ft) minimum depth – Short or wire fencing under 1 metre (3 ft) height
- 90cm (3 ft) depth – Medium 1 to 1.5 metre (3-5 ft) privacy fencing
- 120cm (4 ft) depth – Tall over 2 metre (6 ft) fences in windy regions
In softer, wetter soil that tends to shift:
- Add extra 15-30cm (6-12 inches) depth
- Wider 30cm (12 inch) diameter
- Gravel drainage base layer
This provides extra stability when soil expands and contracts with moisture changes.
Can I use post support spikes instead of concrete?
Pros:
- Faster/easier installation
- Adjustable alignment
- No concrete curing wait time
Cons:
- Not as strong or permanent
- More chance of loosening over years as soil erodes around shallowly buried wood
- Requires perfectly solid, compacted soil or added stabilizer materials
Support spikes can replace concrete effectively in:
- Small or temporary fencing under 60cm (2ft) tall
- Sandy, gravely soil types that won’t erode or shift much
- Combined with angled cross-bracing attached to posts
For tall, heavy duty fencing or installs on loose soil, concrete is recommended for strength, longevity and preventing erosion around buried sections.
How long should I wait before attaching the fence panels?
Before applying sideways load pressure, allow concrete to fully cure:
- Standard premixed concrete – 5 to 7 days
- Quick-setting concrete – 3 days
- Gravelly soil/cool weather – 7+ days
Test post stability by pushing sideways. Concrete should feel solidly anchored with no give or looseness at soil level before attaching panels which can bend or dislodge posts while the concrete is still gaining strength. Consider leaving braces in place up to 2 weeks for assurance.
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