Galvanised
Steel coated in zinc to stop it rusting. Hot-dip galvanising dips the finished part in molten zinc, giving a thick coating that protects cut edges and welds too.
Also called: galvanised steel, galvanising, galvanized, hot dip galvanised
Galvanising is what stops steel fencing rusting away, and it is the single biggest factor in how long a fence lasts outdoors. Zinc corrodes in preference to the steel underneath, so the coating protects the metal even where it gets scratched.
Hot-dip vs pre-galvanised
The distinction matters more than most specifications acknowledge:
- Hot-dip galvanised — the finished component is dipped in molten zinc after it is cut, drilled and welded. Every surface gets coated, including cut ends, drilled holes and weld seams.
- Pre-galvanised — the steel is coated as flat sheet, then cut and formed. Cheaper, but every cut edge and drilled hole is left as bare steel, and that is where rust starts.
For anything going into the ground or staying out in the weather for decades, hot-dip is the one worth paying for.
What it looks like
Fresh galvanising is bright and spangled. Over the first year or two it dulls to a matt grey as the surface weathers — this is normal and not a fault. If a uniform colour matters, powder coating over the galvanising is the answer.
Repairs
Cutting or drilling galvanised steel on site exposes bare metal. Zinc-rich paint on the cut restores most of the protection and is worth keeping in the van on any install where posts get trimmed to height.
Frequently asked questions
- What is the difference between hot-dip and pre-galvanised steel?
Hot-dip galvanising coats the finished component — including cut ends, drilled holes and weld seams — by dipping it in molten zinc after fabrication. Pre-galvanised steel is coated as flat sheet and then cut, which leaves every cut edge as bare steel. For fencing that lives outdoors for decades, hot-dip is the one worth paying for.
- Why has my galvanised fence turned dull grey?
That is normal weathering, not a fault. Fresh galvanising is bright and spangled, and over the first year or two it dulls to a matt grey as the surface weathers — the protection is unaffected. If a uniform colour matters, powder coating over the galvanising is the answer.
- Does cutting or drilling galvanised steel make it rust?
Cutting or drilling on site exposes bare metal at the cut, so it needs touching in. Zinc-rich paint applied to the cut restores most of the protection — worth doing whenever posts are trimmed to height. Small scratches elsewhere are protected sacrificially by the surrounding zinc.