How to install a fence post spike

Video by The Building Sheriff. This walk-through is based on the video "How to install a METPOST/Fence Spike like a pro!" from The Building Sheriff, who runs through the tips and tricks that stop a spike from going in at an angle. Worth a watch before you pick up the sledgehammer — the section on keeping the spike plumb early on is particularly useful.

1. Choose the right spike size for your post

Fence post spikes come in a range of socket sizes — typically 50 mm, 75 mm, and 100 mm square. Match the socket to the cross-section of your fence post. Too loose and the post will rock; too tight and you will struggle to seat it.

Check the spike depth too. A 600 mm spike is suitable for most garden fencing up to around 1.5 m tall. Taller panels or exposed, windy sites call for a 750 mm spike or deeper. To be fair, most people underestimate how much difference an extra 150 mm of ground depth makes in bad weather.

2. Mark the post position clearly

Run a string line between your two end points first. That is the single most important thing you can do before driving a single spike. String lines show up drift immediately; guessing by eye does not.

Mark each post position with a cane or a paint mark on the ground. Double-check the spacing — standard fence panels are 1.83 m (six feet) wide, so post centres are typically 1.83 m apart, allowing a little room to manoeuvre the panels in.

3. Fit the driving cap and seat the spike

Fit the metal driving cap that comes with most spikes — or buy one separately if you have lost it. It drops into the socket and protects the collar from hammer damage. Without it, the first few blows will splay the top of the socket and the post will never sit properly.

Hold the spike upright over your mark and give it a couple of light taps with a sledgehammer to set the point into the ground. At this stage you just want it standing on its own, not driven deep.

4. Check plumb on two faces before driving deeper

This is where most DIYers go wrong — they get enthusiastic and drive the spike six inches before checking if it is straight. By then it is almost impossible to correct without pulling it out and starting again.

Place a spirit level on one flat face of the socket. Adjust until the bubble is centred. Then check the adjacent face. Both need to read plumb before you carry on. That said, the ground will do its own thing as you drive, so keep checking every few blows.

5. Drive the spike down in stages

Work in short bursts — half a dozen firm blows, then stop and re-check with the spirit level on both faces. If the spike has drifted, use the handle of the sledgehammer as a lever to push it back. You have room to correct things while the spike is still shallow; less so once it is halfway in.

On harder ground you may find it easier to rotate the spike a quarter-turn periodically, so the point cuts into undisturbed soil rather than following a channel it has already made. Mind you, soft ground has its own hazards — if the spike goes in too easily, pack the hole around the socket with hardcore or sharp sand once the post is in.

6. Insert the fence post and tighten the bolts

Once the spike is fully home and still plumb, lift the driving cap out and slide the post into the socket. Most metpost spikes have two coach bolt holes through the collar — fit the bolts, add the nuts, and tighten with a socket set or spanner.

Do not overtighten. You want the post clamped firmly without splitting the timber. Snug the bolts down, check the post is upright one final time, and then move on to the next one. Repeat down the whole run before fixing any panels — it is much easier to make small adjustments while everything is still loose.

When to call a handyman

Call Richard if the ground is solid clay or chalk and the spike will not drive without bending, if a spike has gone in at a bad angle and you cannot pull it, or if you are putting up a long run of fencing and want it done in a day. Putting up panels single-handed is also awkward — having a second pair of hands, or someone who has done it a few times, speeds things up considerably.