Start with an honest assessment of the gate

Before you reach for a spanner, spend ten minutes working out what you are actually dealing with. Garden gates in the UK tend to be one of four things: wrought iron, mild steel (often box section or flat bar), cast aluminium, or a timber frame with metal fittings. That matters enormously, because only the first two will respond kindly to heat and welding. Aluminium needs different filler and a much lighter touch, and cast metal can crack if you shock it cold.

Push and lift the gate as you open it. A gate that drops as it swings is telling you the hinge is worn, not the frame. A gate that rubs at the bottom but sits square when closed usually has a bent stile. Check the latch gap too — if you can see daylight of more than about 6mm between the gate edge and the post, the strike plate is probably the culprit rather than the catch itself.

Look closely for the classic failure points:

• Rust bloom around welds and hinge fixings — the paint has failed and water is sitting in the joint.
• Elongated screw holes in hinge plates, where the timber or metal has given way.
• Worn pintles — the pin inside a strap hinge can lose several millimetres over twenty years.
• Fatigue cracks radiating from the corners of a welded frame, often hidden under filler.

Straightening a bent gate frame

Small bends in flat bar or box section can often be taken out cold, using a vice and steady hand pressure. Go slowly and check with a straight edge as you go. Cold working metal hardens it, so if you overdo it you will create a brittle spot that cracks later.

For anything more than a gentle curve, heat is your friend. A propane torch will not get you far on thick steel; you want oxy-propane or oxy-acetylene, or a decent MAPP torch on thinner sections. Heat the bend to a dull cherry red — roughly 700 to 900°C — and work the metal back with a hammer over a solid surface. A wooden mallet or a soft-faced hammer will bruise less. Let it cool slowly in air rather than quenching, unless you specifically want the metal harder and more brittle.

Be realistic about twisted frames. If a gate has a pronounced figure-of-eight twist, straightening it in situ is rarely worth the effort. Take it off its hinges, lay it flat on a pair of trestles, and work it there.

Welding and brazing repairs at home

A small MIG welder running on a domestic supply will handle most garden gate repairs comfortably. Clean the joint back to bare metal with a flap disc, clamp it square, and tack at both ends before running any long beads. Stitch welds — short runs of 25mm or so, alternating sides — will keep distortion to a minimum.

If the section is thin, or the work is ornamental, brazing with a flux-coated rod is often the better choice. It runs at a lower temperature, so you are less likely to blow a hole through a decorative scroll, and the joint is perfectly strong for a gate.

Safety deserves a proper mention here. Galvanised metal gives off zinc fumes that will make you genuinely ill — grind the coating back well beyond the weld zone, and work outside or with forced ventilation. Keep a dry powder extinguisher within arm's reach, clear any dry grass or leaves, and stay with the work for a full hour after you finish. Smouldering timber in a gate post can take a surprisingly long time to show itself.

Replacing worn hinges

Most garden gates hang on one of three patterns: a T-hinge, a band-and-gudgeon, or an adjustable hook-and-band hinge with a threaded pin. The adjustable type is a gift, because you can wind the gate up or down by a few millimetres without touching the frame — well worth fitting if you are replacing a pair anyway.

To swap a hinge, support the gate on blocks so the weight is off the fixings. Drill out rivets rather than grinding them, which keeps the surrounding metal cool. If the new hinge uses the same hole centres, so much the better; otherwise weld the old holes shut, grind flush, and start fresh. Where the gate hangs on timber, replace screws with coach bolts or through-bolts and a plate on the far side. Screws alone will pull out again within a season.

Fitting a new latch or catch

A sagging, sticky latch is usually a geometry problem rather than a broken mechanism. Fit the new catch with the gate held closed and wedged, not propped open, so the alignment is true to how it actually sits. Aim for 3 to 6mm of clearance between the latch bolt and the keep — enough for seasonal swelling, tight enough to stop the gate rattling.

If the latch is a thumb-latch or Suffolk pattern, check the spring before condemning the whole fitting. A stretched spring can often be replaced on its own for a couple of pounds, which saves drilling new holes in a post that has already seen a few.

Finishing the job properly

Any repair you have welded or brazed will rust unless you seal it. Wire-brush the whole area back to bright metal, treat any remaining corrosion with a rust converter, then apply a red oxide or zinc-rich primer before your topcoat. Two thin coats beat one thick one every time.

Finally, oil the hinges. A few drops of light machine oil on each pintle twice a year will add a decade to their life, and it takes less time than reading this paragraph. A well-maintained gate is a small pleasure — and one you will notice every time you walk through it.