Rusted gate hinge: repair it yourself or call for welding

Where the rust actually starts

Rust on a gate almost never starts on the flat surfaces you can see. It starts where water sits: the weld seam where the hinge pin meets the post, the bottom of a hollow box-section gate where condensation collects and never dries, and the point where the post goes into the ground or its concrete footing.

Estonian weather is hard on this kind of joint. Repeated freezing and thawing gets into hairline gaps in old paint or galvanising, and road salt carried on tyres and boots adds to it if the gate is near a driveway. Once rust starts under a paint layer, it spreads sideways under the surface long before it shows through.

This is why a gate can look fine from a distance and still be structurally thin at the hinge. The squeak or sag you notice is often the first visible sign of damage that has been building for years.

How to judge how deep the rust has gone

Start with a wire brush or a flap disc on an angle grinder and clear the paint and loose scale from the hinge area and the post at ground level. Do this on a dry day; wet rust just smears rather than coming off.

Once you can see bare metal, tap it with a hammer. A dull, solid sound means the steel underneath is sound. A hollow or crumbly sound, or a spot where the hammer goes through the surface, means the rust has eaten into the wall thickness of the tube or the hinge plate itself.

Check the post at ground level particularly carefully, ideally by digging a little around the base. Posts rust fastest right where they meet the ground or the concrete, because that is where moisture sits longest and is hardest to see.

If the rust is only on the surface: grinding and painting

Surface rust that hasn't eaten into the metal is a realistic DIY job. Grind or wire-brush back to bare, sound steel, going a little beyond the rusted area so you're not painting over a feathered edge that will lift later.

Wipe the bare metal with a rag and white spirit to remove grinding dust and any oil, then apply a rust-converting or zinc-rich primer within the same day, before any new surface rust forms. Two thin coats are better than one thick one.

Finish with an exterior metal enamel once the primer has cured, matching the original colour if you're only doing a patch repair. If the hinge itself moves stiffly rather than rusted through, clean the pin, apply a light machine oil or graphite grease, and work the gate back and forth until it moves freely again.

If it's structural: what not to attempt yourself

If the hammer test shows a hollow sound, a hole, or metal that flakes away under the grinder, you're past a paint repair. Grinding back a weakened hinge plate or post wall and painting over it hides the problem without solving it, and the gate will fail again, often suddenly and under load.

The mistake most people make at this point is grinding a thin spot smooth, priming it because it looks tidy, and trusting it to hold the weight of a swinging gate. A hinge that looks solid with paint on it can still tear away from a wall of steel that has thinned to almost nothing.

Do not attempt to weld a repair yourself if you haven't welded before, and do not try to prop or force a sagging gate back into line with the post; the load on a bent or rusted hinge can shift unpredictably and the gate is heavier than it looks.

• Hollow or crumbly sound when tapped with a hammer
• Grinder goes through the metal rather than smoothing it
• Visible daylight or a hole where the hinge plate meets the post
• Post leaning or loose at ground level, not just at the hinge
• Gate has dropped enough that it drags on the ground or the latch no longer lines up

When to call a welder or a metal fitter

Once the rust has gone through the wall of the tube or hinge plate, the fix is cutting out the damaged section and welding in new steel, then treating and painting the repair as above. This is a job for a welder, and it's from 55 € per hour with us, usually a couple of hours for a single hinge repair depending on access and how much needs cutting out.

If the post itself has rusted through at ground level, the more reliable fix is usually a new post section set in fresh concrete rather than patching the old one, since a patched post at ground level tends to rust through again at the same spot. That's metal fitting work, from 45 € per hour, and we can quote it as a fixed price once we've seen the gate or a few photos.

If the whole gate is old enough that the frame, hinges and post are all showing the same wear, it's often more sensible to look at the gate and fence together rather than fixing one hinge at a time. Fence repair and installation is also from 45 € per hour, and a single visit can cover the gate, the post and the run of fence either side of it.

How to stop the rust coming back

A repaired or repainted gate will still rust again in the same places if water is left to sit there. Check that the post has a cap or is otherwise sealed at the top, since an open-topped hollow post fills with rainwater and rusts from the inside where you'll never see it until it fails.

At ground level, keeping soil and grass from banking up against the post helps a great deal, since that keeps the base drier and slows the same failure from repeating. A coat of bitumen paint or similar on the buried section of a new post, before it goes into the ground, adds a fair amount of protection.

Once a year, look over the hinge area, the weld seams and the base for any paint that has started to bubble or lift, and touch it up before rust gets underneath again. Ten minutes with a brush each spring is far cheaper than a welding repair later.