Description
Treated softwood fence posts are the foundation of strong, long-lasting fencing and outdoor structures. Manufactured from sawn softwood and pressure treated for durability, these posts are designed for exterior use and are suitable for in-ground installation where required.
We stock both standard and specialist sizes, including options not commonly held by many builders’ merchants. Whether you’re installing garden fencing, hanging gates, or constructing heavier-duty outdoor structures, selecting the correct post size and length is critical for long-term performance.
Common Fence Post Sizes & Lengths
- 3x3 (75×75mm) – 6ft, 8ft & 10ft lengths
- 4x4 (100×100mm) – 6ft, 8ft, 10ft & 12ft lengths
- 5x4 (125×100mm) – 10ft length
- 6x3 (150×75mm) – 7ft weathered top & 8ft square top
- 6x4 (150×100mm) – 8ft length
- 6x6 (150×150mm) – 8ft, 10ft & 12ft lengths
- 7x7 (175×175mm) – 8ft pointed top
This wide size range allows you to buy the correct post for your project, rather than adjusting your build to suit limited stock availability.
What Length Fence Post Do I Need?
For in-ground installations, a common rule of thumb is to allow 450mm–600mm of the post below ground level to ensure stability.
- 6ft fence height → typically 8ft (2.4m) post
- 5ft fence height → 7ft (2.1m) or 8ft post
- 6ft fence in exposed areas → 10ft post may be recommended
If using a bolt-down support on concrete, you generally do not need to allow additional length for burial, meaning a 6ft fence may only require a 6ft post.
Fence posts are commonly spaced at 1.8m–2.4m centres, depending on the fencing system being installed.
Typical Uses by Size
75 × 75mm (3×3) treated fence posts
- Standard garden fencing
- Featheredge fencing and panel installations
- Light-duty landscaping projects
- Not recommended for gates or heavy structural loads
100 × 100mm (4×4) treated fence posts
- Heavier garden fencing
- More stable option for exposed locations
- Small to medium gate installations (depending on weight)
- General-purpose structural fencing
125 × 100mm (5×4) treated fence posts
- Gate posts
- Fence ends, corners and return points
- Areas subject to increased load or movement
150 × 75mm (6×3) treated fence posts
- Heavier-duty fencing layouts
- Applications where a rectangular profile is preferred
- Weathered top option helps shed water
150 × 100mm (6×4) treated fence posts
- Stronger alternative to 4x4 posts
- Fence ends and structural support points
- Mid-point option between 4x4 and 6x6 posts
150 × 150mm (6×6) treated fence posts
- Driveway and garden gate posts
- Pergolas and outdoor structures
- High-load boundary applications
175 × 175mm (7×7) treated fence posts – pointed
- Decorative boundary and entrance features
- Landscaping and architectural applications
- Visual feature posts within fencing runs
Commonly Used With
- Featheredge Boards
- Treated Gravel Boards
- Exterior-grade fixings
- Postmix or concrete for secure installation
Installation & Handling Notes
- Set posts securely using suitable postmix or concrete
- Allow adequate embedment depth based on fence height and wind exposure
- Freshly cut ends should be re-treated where possible
- Check posts are plumb before allowing concrete to fully set
Why Buy Fence Posts From Wern-Wood?
- Standard and specialist sizes in stock
- 6ft to 12ft length options available
- Square top, weathered top and pointed variants
- Suitable for fencing, gates and structural outdoor projects
- Trade and public supply
- Delivery across South Wales or local collection available
Treated fence posts provide a dependable and versatile solution for fencing and outdoor construction, offering strength, durability and long-term performance across a wide range of applications.
Frequently Asked Questions About Treated Fence Posts
What size fence post do I need for a 6ft fence?
For a 6ft fence installed in-ground, an 8ft (2.4m) post is typically recommended to allow 450mm–600mm below ground. If using a bolt-down support fixed to concrete, a 6ft post may be sufficient. For a full breakdown including panel spacing and material quantities, see our Fence Post Spacing Guide.
How many fence posts and bags of postmix do I need?
The number of posts and bags of postmix depends on fence length and post spacing. As a general rule, posts are spaced at 1.8m–2.4m centres. Use our detailed guide here: How Many Fence Panels, Posts & Bags of Postmix Do I Need?.
Are these fence posts suitable for ground contact?
Yes. All of our treated fence posts are pressure treated to UC4 specification, making them suitable for in-ground structural use. Learn more about treatment classes in our guide: UC3 vs UC4 Treated Timber Explained.
What treatment is used on these posts?
These posts are pressure treated for exterior durability and long-term protection against decay and insect attack. If you're unsure which timber treatment is right for your project, read: Which Timber Is Best for Outdoor Use in the UK?.
How far apart should fence posts be spaced?
Fence posts are typically spaced between 1.8m and 2.4m centres depending on the fencing system being installed. For a detailed spacing guide and examples, visit: How Many Fence Posts Do I Need?.
Which fencing systems are these posts suitable for?
These posts are commonly used for featheredge fencing, panel fencing and horizontal systems. You can calculate materials required using our Featheredge Fencing Calculator or our Horizontal Hit & Miss Calculator.
What size screws or fixings should I use?
Fixing size depends on the timber thickness and structural load. For a full breakdown of recommended screw sizes for outdoor projects, see our guide: What Size Screw Do I Need?.
How should fence posts be stored before installation?
Timber should be stored flat, raised off the ground and protected from excessive moisture before use. For best practice, read our guide: How to Store Outdoor Timber Before You Build.
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