For a 6ft (1.8m) fence panel, you need an 8ft (2.4m) post. As a rule, posts should be around 600mm longer than the panel height, as that extra length goes into the ground. The section below ground should be set to a depth of at least 450–600mm and secured with a fast-setting post mix concrete to give the fence stability against wind.
Timber and Concrete Fence Posts for Garden and Boundary Fencing
MacBlair stocks a full range of fence posts in both pressure treated timber and concrete, covering everything from standard garden boundaries to heavier-duty applications. Timber posts are kiln-dried and pressure treated to UC4 standards, meaning they are rated for ground contact and long-term outdoor exposure. Concrete options include slotted intermediate, corner and end posts, which slot directly with fence panels without the need for brackets or additional fixings.
Getting the post size right is critical. As a general rule, posts should be approximately 600mm longer than the fence panel height, with that extra length going below ground. A 6ft panel therefore needs an 8ft post, set to around 2ft depth and secured with Postcrete. Post spacing typically runs at 1.8m to 2.4m centres depending on panel width and exposure. The range covers common heights from 1.8m to 3.0m, in both 75mm x 75mm and 100mm x 100mm sections.
Timber posts work well with fence boards and fence rails in traditional closeboard or featheredge layouts. They can be notched or morticed on site to suit arris rail or rectangular rail systems. Concrete posts suit panel fencing where low maintenance is the priority. Neither rots, neither requires repainting, and both outlast untreated timber by a significant margin. Post types available include:
- Pressure treated square timber posts, suitable for closeboard, panel and gate installations
- Slotted concrete intermediate posts for panel fencing systems
- Concrete corner and end posts for changes in fence line direction
- Larger section timber gate posts for hanging garden gates
Where digging is not an option, bolt-down and drive-in fence post supports provide a practical alternative, particularly on hard standing or existing concrete bases. After installation, protect timber posts with a quality wood preservative treatment to maximise service life. MacBlair offers delivery across Northern Ireland, with collection also available.
Fence Post FAQ's
Timber posts are lighter, easier to cut on site, and suit closeboard and featheredge fencing systems where rails or boards are nailed directly to the post. Pressure treated timber posts rated to UC4 are suitable for ground contact and long-term outdoor use. Concrete slotted posts are heavier but require no maintenance and will not rot. They are the more common choice for panel fencing, as panels simply slot in without the need for brackets or fixings.
Post spacing depends on the panel or board width you are using. Standard fence panels are 1.83m (6ft) wide, so posts are typically spaced at 1.83m centres to accommodate one panel per bay. For closeboard or featheredge fencing, spacing can vary between 1.8m and 2.4m. In exposed or high-wind locations, closer spacing adds extra stability and reduces the risk of panels being blown out.
Setting posts in concrete is the most common and reliable method for a permanent installation. A fast-setting post mix such as Postcrete is poured dry into the hole around the post and sets within minutes after adding water, making it a practical choice for DIY. If digging is not possible, for example on a concrete base or paved area, bolt-down post supports or drive-in metal post spikes are a suitable alternative that avoid the need for concrete altogether.
The most important factor is starting with a pressure treated post rated for ground contact, ideally UC4 treated timber. This treatment is forced deep into the wood fibres under pressure, giving far better protection than surface-applied products alone. The section of post at and just above ground level is the most vulnerable to moisture, so applying a wood preservative treatment to any cut ends before installation adds an extra layer of protection. Keeping the post top pointed or capped also helps shed rainwater and reduces the risk of water sitting on the end grain.