Practical guide
Written by Craig, Foundation Garden & Trees
Concrete posts generally outlast timber because they cannot rot, and slotted concrete posts let panels be changed easily. Timber posts look more natural, suit feather edge fencing built on rails and are lighter to handle. The right choice depends on the fence style, how exposed the boundary is and how you want it to look.
7 minute readUpdated October 2026Last updated:
Rot at ground level is the usual reason timber posts fail.
Slotted concrete posts hold panels; mortice posts take timber rails.
Gravel boards keep the timber above damp soil.
Setting depth and footing matter as much as the post material.
When a garden fence leans or blows down, the boards or panels are rarely the first thing to go. It is usually the posts, and specifically the section just at and below ground level, where timber stays damp and air can still reach it. Choosing the right post and setting it well is the most important decision in any new fence, whatever goes between the posts.
Concrete posts come in two main types. Slotted posts have a channel down each side, and fence panels drop into the slots from above. They are quick to fit and make replacing a damaged panel simple, because the panel lifts out without unscrewing anything. Mortice posts have holes through them to take timber rails, which is how a feather edge or close board fence can be built on a concrete frame.
The trade-off is weight and appearance. Concrete posts are heavy to carry, especially through a house or down a narrow side passage, and some people prefer the look of timber from the garden side. Many concrete posts are reinforced with steel, and once set they will not rot.
Good timber posts are pressure treated to resist rot and sized to suit the height of the fence. They are easier to cut, carry and fix to, and they give a uniform wooden look on both sides. Their weak point is always the base. Setting them in well-compacted gravel or concrete with the top of the footing shaped to shed water helps, as does keeping soil and mulch from piling up against them.
Where an old timber post has rotted off at ground level but the rest is sound, a concrete or metal spur can sometimes be set alongside and bolted to it. That is a repair rather than a new fence, but it can extend the life of a boundary that is otherwise in good order.
A gravel board runs along the bottom of the fence between the posts, lifting the boards or panel clear of the soil. Concrete gravel boards are common with both concrete and timber posts, and timber boards are available too. Either way, they take the contact with damp ground so the fence above does not. The photograph on our fencing page shows Craig's own feather edge fence on concrete gravel boards with a matching gate.
A solid fence acts like a sail. On open boundaries, which are common across the flat land of Suffolk and Norfolk, posts are under real pressure every time a strong wind comes through. Concrete posts set deeply resist that well. Timber can too, if the posts are thick enough, set to a good depth and spaced correctly. Whatever you choose, the ground matters: loose sand and soft clay both need a firm footing.
One popular arrangement uses concrete posts and gravel boards with timber above, which aims to combine the durability of concrete at ground level with the look of wood. Feather edge boards can be fixed to rails held in mortice posts, and panels can sit in slotted posts. If you are still deciding between those two infill styles, our guide to feather edge versus panel fencing compares them for privacy, slopes and repairs.
If one post has failed in an otherwise sound fence, it can often be replaced on its own. Removing the old footing is usually the hardest part, especially if it was set in a large lump of concrete. Concrete posts are heavier to swap, but slotted panels lift out easily to make room. Our guide to fence replacement cost factors explains what affects a repair or a full replacement, and fencing can also be planned alongside other landscaping work so levels and edges are done once.
Common questions
Generally yes, because concrete does not rot. Well-treated timber set properly can still last a good number of years, but ground level rot is the usual reason timber posts fail.
Yes. Mortice concrete posts take timber rails, and the feather edge boards are then fixed to the rails in the usual way.
They are heavier to handle, and an old footing still has to be broken out. With slotted posts, though, the panels lift out easily, which helps.
Not always. Timber posts can be set in concrete or in well-compacted gravel. What matters is a firm footing at the right depth with water shed away from the post.
The post needs to be the height of the fence plus the depth set into the ground, and a gravel board if one is used. That usually means a post noticeably longer than the fence is tall.
Straightforward advice
Call Craig or send photos, your location and a short description for an initial estimate.
