Fence Posts

Concrete and timber fence posts both serve the same structural purpose but differ significantly in durability, maintenance, and long-term cost. Concrete posts do not rot, are unaffected by ground moisture, and will outlast the fence panels themselves — making them the preferred choice for any installation intended to last 20 years or more. They are available in slotted versions that allow panels and gravel boards to simply slide into position, which also makes future panel replacement straightforward. Timber posts have a more natural appearance and are lighter to handle during installation, which can make DIY projects easier. However, even pressure-treated timber posts in direct ground contact can begin to rot at the base within 5 to 10 years, particularly in wet or heavy soil. For a permanent boundary fence, concrete posts paired with gravel boards provide the most durable and low-maintenance result. Timber posts are a reasonable option for temporary fencing or lower-budget projects where longevity is less of a priority.

The standard rule for fence post depth is to bury approximately one third of the total post length underground. For a 1.8 metre (6ft) fence, this means a minimum hole depth of 600mm is required, with the post extending to around 2.4 metres in total length. In exposed locations, windy sites, or where the soil is sandy or loose, increasing the depth to 750mm provides significantly better stability. Deeper footings reduce the risk of posts leaning or blowing over in high winds, particularly for solid panel fencing which catches the wind like a sail. The hole should be approximately three times wider than the post itself to allow sufficient concrete or Postcrete to be packed around it. For fence posts supporting gates, corner posts, and end posts, a deeper and wider footing is always advisable as these positions experience greater load and stress than intermediate posts. Skimping on post depth is one of the most common causes of fence failure and is not a shortcut worth taking.

For standard UK fence panels, which are typically 1.83 metres (6ft) wide, posts should be spaced so that the clear gap between the inside faces of adjacent posts is exactly 1.83 metres. This ensures panels fit correctly without needing to be cut or forced into position. When measuring centre to centre rather than face to face, you need to add one post width to that figure — for a 100mm post, this gives a centre-to-centre spacing of approximately 1.93 metres. For closeboard or feather edge fencing where boards are fixed directly to horizontal rails, post spacings of up to 2.4 metres are common. In exposed or high-wind locations, reducing spacing improves the structural integrity of the fence line considerably. Always check your panel dimensions carefully before setting posts, as even small variations between manufacturers can result in panels that do not fit. It is also important to account for corner posts, gate posts, and end posts, all of which require individual consideration when planning your spacing layout.

For a standard 1.83 metre (6ft) fence with gravel boards, a post length of approximately 2.4 metres is required to allow for 600mm of depth in the ground, the height of the gravel board, and the full panel height above ground. Without gravel boards, a 2.1 metre post may be sufficient, though 2.4 metres is still the more common and recommended choice as it provides a deeper footing and greater stability. In terms of section size, 75mm x 75mm (3x3 inch) timber posts are the minimum for residential panel fencing, but 100mm x 100mm (4x4 inch) posts are strongly recommended for 1.8 metre fences as they provide considerably better wind resistance and longevity. For concrete slotted posts, standard intermediate posts for 6ft fencing are typically supplied at 2.36 or 2.4 metres. Corner, end, and gate posts should always be a heavier section than intermediate posts to handle the additional loads placed on them. Using undersized posts is a false economy — a heavier post costs relatively little more but makes a significant difference to the long-term performance of the fence.

Yes, setting fence posts in concrete or a fast-setting post mix such as Postcrete is strongly recommended for any permanent fence installation. Concrete anchors the post firmly in the ground, prevents movement and leaning over time, and significantly reduces the risk of the fence blowing over in high winds. For a standard residential garden fence, two to three bags of Postcrete per post is typically sufficient — use three bags for softer ground or taller, more exposed sections. The Postcrete or concrete should be poured around the post to ground level and the top finished with a slight slope away from the post to encourage water runoff rather than pooling around the timber base. Allow the concrete to cure for at least 24 to 48 hours before attaching fence panels, as fitting panels too early can knock posts out of alignment before the concrete has set. In hard standing areas such as concrete or tarmac, post spike anchors can be used as an alternative to concreting, though these are best suited to lighter fencing rather than full-height solid panel fences in exposed positions.

Slotted fence posts have a machined channel running down one or both sides that allows fence panels and gravel boards to slide directly into position without the need for brackets or fixings. They are available in both timber and concrete versions and are the most widely used post type for standard garden panel fencing in the UK. The slot makes installation faster and more straightforward, particularly when working alone, as panels can be held in place by the post while you work along the fence run. Slotted concrete posts are the preferred choice for long-term installations as they eliminate the risk of post rot entirely — the panels sit within the slot and can be lifted out and replaced individually without disturbing the posts themselves. Solid or non-slotted posts require panels to be fixed using brackets or screws and are more typically used for closeboard, feather edge, or bespoke fencing where boards are fixed directly to the post or to horizontal arris rails. For most homeowners installing standard fence panels, slotted posts — particularly concrete versions — offer the simplest, most durable, and most cost-effective long-term solution.

The lifespan of a timber fence post depends primarily on the quality of the treatment, the soil conditions, and how well the post is installed and maintained. Untreated softwood posts in ground contact can begin to rot within just a few years, particularly in damp or clay-heavy soils. Good quality pressure-treated timber posts rated for ground contact — typically UC4 treatment class — will last considerably longer, with manufacturers often guaranteeing 15 years or more against rot and fungal decay. However, independent testing and real-world experience suggest that even well-treated posts can fail at the base within 10 to 15 years in persistently wet conditions. Applying a cut-end preservative to any sawn surfaces before installation, ensuring the top of the post is angled or capped to shed rainwater, and fitting post caps to prevent moisture entering the end grain all contribute to extending the service life. For the longest-lasting fence, concrete posts eliminate the rot risk entirely and are always the recommended choice for any boundary fence expected to stand for 20 years or more.

Replacing a fence post mid-run is one of the more challenging aspects of fence maintenance, but it can often be done without fully dismantling adjacent panels if approached carefully. With slotted concrete or timber posts, fence panels can usually be lifted clear of the slot and temporarily supported while the old post is removed and a new one installed in its place. Removing the old post typically requires breaking out the surrounding concrete, which can be done with a cold chisel and lump hammer or by hiring a post-puller tool for larger jobs. Once the new post is set and the concrete has cured, panels can be slid back into the slots. For non-slotted posts where panels are screwed or bracketed into position, more careful dismantling is usually required, though an experienced DIYer can often remove and refit panels without causing damage. If the post has rotted at ground level but the above-ground section remains solid, a post repair spur — a metal or concrete repair spike driven into the ground alongside the old post — can be used to extend the life of the existing post without a full replacement. This is a cost-effective short-term fix but should be considered a temporary solution rather than a permanent repair.

Gravel boards are not strictly required, but they are strongly recommended for any timber fence panel installation and are considered best practice by professional fencing contractors. A gravel board is a horizontal board or concrete unit fitted at the base of the fence between posts, sitting at ground level beneath the fence panel. Its purpose is to keep the bottom edge of the timber fence panel away from direct contact with damp soil, grass, and standing water — the primary cause of premature rot in panel fencing. Concrete gravel boards offer the best protection as they are completely unaffected by moisture and will last indefinitely alongside concrete posts. Timber gravel boards are a more economical option and, when pressure-treated, provide good protection for many years. Fitting gravel boards can significantly extend the lifespan of your fence panels and is a particularly worthwhile investment on sites with heavy clay soil, poor drainage, or where the fence line runs through a lawn. Many fence panel manufacturers also require gravel boards to be fitted in order for their product guarantee to remain valid, making them an essential rather than optional component of a properly installed fence.

Post caps are covers fitted to the top of fence posts to protect the exposed end grain of the timber from rain, frost, and moisture absorption. The end grain of a timber post is the most vulnerable part of the wood — it absorbs water far more readily than the face grain, which over time causes the timber to split, crack, and accelerate decay from the top down. Fitting a post cap is a simple and inexpensive measure that can meaningfully extend the life of a timber post by preventing water pooling on the flat top surface. Caps are available in a range of profiles including flat, pointed, ball, and acorn finials, making them a decorative feature as well as a practical one. For concrete posts, caps serve a primarily decorative purpose as concrete is not susceptible to the same moisture damage. Most timber fence post suppliers offer matching caps designed to fit their post sections, and they are generally easy to fit with a couple of screws or exterior adhesive. Given the low cost and the protection they provide, post caps are always worth including in any new fence installation using timber posts.