One Wobbly Post in an Otherwise Sound Fence

Find out what is moving

Push the post steadily and watch the ground at its base. If the whole concrete collar rocks in the soil, the concrete is intact and the hole is the problem, usually because it was too small or too shallow. If the post moves but the concrete stays still, the post has failed inside the concrete or the bond between them has gone.

Also check whether the post moves along the fence line or across it. Movement along the line often means a neighbouring bay is loading it, which is worth knowing before anything is dug out.

• Whole collar rocking: undersized or shallow foundation
• Post moving inside a static collar: rot or bond failure at the post
• Movement along the fence line: load coming from an adjacent bay or a gate

The screwdriver check at ground level

Push a screwdriver into the timber right where it enters the concrete or soil. Sound timber resists. Timber that takes the screwdriver easily has gone at exactly the point that carries the whole load, and no amount of packing or bracing will bring it back.

This check matters because a post can look perfect above ground and be finished at soil level, which is where nearly all timber post failure happens.

Why one post and not the others

There is usually a reason a single post fails first. It might be at the end of the run where wind load concentrates, it might be next to a downpipe or a soakaway that keeps the ground wet, it might be carrying a gate, or the hole for that one post might have hit a service or a buried obstruction and been dug shallower than the rest.

Working out why is worth ten minutes, because if the cause is standing water or a gate load, replacing the post the same way it was done before will produce the same result.

• End of run posts take more wind load than mid run posts
• Posts near downpipes and soakaways sit in wetter ground
• A post carrying a gate does a completely different job from a fence post

Repairing without taking the fence apart

Where the boarding is sound, a single post can usually be replaced with the panels or boarding kept in place, with the old concrete broken out and a properly sized new foundation formed. A concrete post or a concrete spur bolted to a timber post removes the ground contact failure point altogether, which is often the sensible upgrade on the one post that has already gone.

That approach also keeps the fence looking consistent, because nothing above ground level changes.

What you can safely do yourself

Clearing soil and planting away from the base, checking neighbouring posts for the same softness, temporarily easing the load by removing a heavy trellis topper, and photographing the base for a contractor are all sensible.

What rarely works is wedging stones or hardcore into the gap, screwing a batten across the fence, or pouring fresh concrete on top of a failed collar. All three transfer the load to the next weak point, and a fence post that is rotten at ground level cannot be stabilised from above.

• Do check the neighbouring posts, since they were installed the same day
• Do reduce the load if a heavy topper is fitted to that bay
• Do not pack the hole or brace the post as a permanent fix

One post, priced honestly

Single post repairs are ordinary work for us and we are happy to do them across London and Hertfordshire. We will also tell you if the neighbouring posts are close behind, because doing three at once costs less than three separate visits.

Ring 07885907880 or use the enquiry form and we will come and look at the base of the post rather than guess from a photo alone.

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