How to repair a fence post

Video by Charlie DIYte. This walk-through is based on the video "How to DIY Repair Your Garden Fence" from Charlie DIYte, who walks through his real-life repair after a storm flattened his garden fence. It is a straightforward, honest account of what works and what does not — the section on reinforcing the post base so it will not go over again is well worth watching before you just stick it back up the same way it came down.

1. Work out whether the post can be saved

Push the post firmly with your hand or foot. A post that wobbles but springs back is often still structurally sound above ground — the problem is usually at the base. A post that stays leaning when you let go, or that you can twist by hand, has either rotted through below ground level or snapped at the concrete collar.

If the post is solid above ground and the rot is only at the very base, you have options. If the post is soft and punky more than 300 mm above ground level, it is generally better to replace it outright. Trying to repair a post that is half gone tends to be a short-term fix that fails in the next storm. It depends on how much of the post is still good.

2. Clear around the post base and assess the footing

Dig out or scrape back the soil around the base of the post to see what you are dealing with. A lot of garden posts in this part of Kent were put in with a bag of postcrete poured dry into the hole — quick and easy, but the concrete collar often ends up cracking over the years and letting water sit against the timber.

If the post is set in concrete and the concrete is still solid, the problem is probably the timber inside it rotting off. If the concrete itself is loose or heaving, the repair is more involved. Either way, seeing the base clearly is the starting point. You cannot really plan the fix until you know what has failed.

3. Use a post repair spike for a rotten base

A post repair spike — sometimes called a post saver or base repair spike — is a metal bracket with a driven spike on one end and a socket for the post on the other. You cut the post off cleanly above the rot, drive the spike into the ground next to or through the old concrete, then bolt the good section of post into the socket.

This is genuinely one of the most useful products for garden fencing. It avoids having to dig out an old concrete footing, which is hard work and often damages surrounding turf or paving. The spike can be driven with a post driver or a sledgehammer and a driving cap, just as you would with a regular metpost. Check the post is plumb before fully driving the spike home — corrections get harder the deeper it goes.

4. Cut the post square and treat the cut end

Use a handsaw or a circular saw to cut the post at a right angle, removing all the rotten or soft wood and leaving a clean, solid face. Make sure you have cut high enough that the remaining post timber is genuinely sound — probe with a screwdriver if you are unsure. Soft or stringy wood means you need to go higher.

Once cut, paint the exposed end grain immediately with end-grain preservative or a liberal coat of fence treatment. End grain soaks up water much faster than the face of the timber and will rot out again surprisingly quickly if left untreated. Give it two coats if you can. It takes five minutes and adds years to the repair.

5. Brace the post plumb and secure the panels

Once the post is in the repair spike and upright, brace it temporarily with a couple of lengths of scrap timber nailed to pegs in the ground, so it holds position while you tighten the bolts and refit the panels. It is much easier to do this with a second person holding the post steady, though you can manage alone if you are methodical about it.

Refit the fence panels or arris rails to the repaired post using galvanised screws or joist hangers rather than nails if you can. Screws hold better over time and can actually be removed if you need to do the job again in ten years. Nails work loose as the timber expands and contracts through the seasons, and after a few years they are barely holding anything.

6. Improve drainage to prevent the same problem recurring

Most fence posts rot at the base because water sits against the timber at ground level, particularly where soil or lawn has built up around the post over the years. Once the repair is done, bank the soil away from the post slightly so water drains away rather than pooling around the base.

You can also fit a post cap to the top of any exposed post ends — a simple plastic or metal cap that stops rainwater sitting on the end grain at the top. It costs almost nothing and makes a noticeable difference to how long the post lasts. Mind you, the base is almost always where the rot starts, so sorting the drainage there is the main thing.

When to call a handyman

Call Richard if the post is set in solid concrete that needs breaking out, if you have multiple posts down after a storm and need a full run of fencing reinstated, or if the ground is hard chalk or compacted clay and a repair spike simply will not drive without bending. A long run of leaning panels that need straightening and re-securing is also the kind of job that benefits from an extra pair of hands and the right kit on site.