Fence Post Spacing Guide
Fence Post Spacing, Depth and Installation Guide
Fence posts are the foundation of every fence. Get the spacing wrong and panels will not fit. Set them too shallow and the fence blows over in the first storm. This guide covers everything you need to know about post spacing, depth, materials, and installation technique.
Spacing by Panel Width
| Panel Width | Post Spacing (centre to centre) | Posts per 10m Run | Notes |
|---|---|---|---|
| 1.83m (6ft) | 1.83m | 7 | Most common panel size |
| 1.8m (metric) | 1.8m | 7 | Metric equivalent, slightly narrower |
| 1.5m (5ft) | 1.5m | 8 | Used for shorter fences |
| 2.4m (ranch rail) | 2.4m | 6 | Open-rail fences only |
| 3.0m (post and rail) | 3.0m | 5 | Agricultural and rural boundaries |
The rule is simple: post spacing equals panel width. Every panel sits between two posts, and you always need one more post than the number of panels. A 10m fence with 1.83m panels needs 6 panels and 7 posts.
Post Depth by Fence Height
| Fence Height | Minimum Post Depth | Recommended Depth (exposed site) | Total Post Length Needed |
|---|---|---|---|
| 0.6m (2ft) | 300mm | 400mm | 1.0m |
| 0.9m (3ft) | 450mm | 500mm | 1.5m |
| 1.2m (4ft) | 500mm | 600mm | 1.8m |
| 1.5m (5ft) | 550mm | 650mm | 2.1m |
| 1.8m (6ft) | 600mm | 750mm | 2.4m |
| 2.0m (6.5ft) | 650mm | 800mm | 2.7m |
The one-third rule is the standard: bury at least one-third of the total post length underground. Wind is the biggest enemy of a fence, and the below-ground section provides the leverage to resist it. A 1.8m fence in an exposed coastal or hilltop location should use 750mm depth minimum.
Post Material Comparison
| Material | Cost per Post | Lifespan | Weight | Rot Resistance | Best For |
|---|---|---|---|---|---|
| Dip-treated softwood | EUR 5-10 | 5-10 years | Light | Low | Temporary fences, budget projects |
| Pressure-treated softwood | EUR 8-18 | 15-25 years | Light | High | Most garden fences |
| Hardwood (oak) | EUR 20-40 | 20-30 years | Medium | Very high | Premium fences, heritage properties |
| Concrete | EUR 15-30 | 50+ years | Heavy | Immune | Permanent boundaries, windy sites |
| Galvanised steel | EUR 25-45 | 25-40 years | Light | Immune (if coating intact) | Modern fences, composite panels |
Pressure-treated softwood posts are the best all-round choice. They balance cost, durability, and ease of handling. Concrete posts are worth the extra weight for permanent boundaries where you never want to replace a post again.
Installation Step by Step
Follow these steps for a straight, solid fence line:
- Mark the line — Drive a stake at each end of the fence run and stretch a string line between them. This is your reference for every post.
- Mark post positions — Measure along the string line and mark each post position with a spray dot or small stake. Double-check that panel widths fit between marks.
- Dig the first end post hole — Dig to the required depth (see table above) and 300mm diameter. Keep the sides vertical.
- Set the first end post — Place the post in the hole, check plumb with a spirit level on two adjacent faces, and fill with Postcrete or concrete. Brace with scrap timber.
- Set the last end post — Repeat at the other end of the fence run.
- Run the string line — Attach a new string line between the two set posts at the top. This guides all intermediate posts.
- Set intermediate posts — Working from one end, dig each hole, set the post so it just touches the string line, check plumb, and fill with concrete. Brace each post.
- Wait for concrete to set — Postcrete sets in 5-10 minutes. Standard concrete needs 24-48 hours before you hang panels.
- Install gravel boards — Fit gravel boards between posts at ground level to protect panel bases from rot.
- Hang panels — Lift each panel into position and secure with panel clips, brackets, or galvanised nails.
Common Mistakes to Avoid
| Mistake | Consequence | Prevention |
|---|---|---|
| Posts too shallow | Fence leans or blows over | Follow the one-third depth rule |
| No string line used | Wavy, crooked fence line | Always set end posts first and run a string line |
| Concrete above ground level | Traps water against the post, accelerating rot | Keep concrete 25mm below ground level and slope it away from the post |
| No gravel boards | Panel base rots from ground contact | Fit gravel boards to every bay |
| Hanging panels before concrete sets | Posts shift out of plumb | Wait for full cure (10 min for Postcrete, 24h for concrete) |
| No post caps | Rain soaks into end grain, causing splits and rot | Fit a post cap to every post |
Postcrete vs Standard Concrete
| Feature | Postcrete (fast-set) | Standard Concrete (mixed) |
|---|---|---|
| Cost per post | EUR 5-8 | EUR 2-4 |
| Setting time | 5-10 minutes | 24-48 hours |
| Strength | Good for standard fences | Stronger for gates and tall fences |
| Ease of use | Pour dry mix, add water | Mix cement, sand, gravel, then pour |
| Best for | DIY, most garden fences | Large projects, heavy-duty posts |
Postcrete is the go-to choice for garden fence posts. It is faster, easier, and eliminates the need for a cement mixer. For gate posts and fences over 2m tall, standard concrete provides a more substantial foundation.
These calculations are estimates only. Actual requirements may vary depending on surface conditions, product specifications, and installation methods. Always consult a qualified professional for precise measurements.
Prices updated: 2026-03Frequently Asked Questions
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