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The Uncompromising Standard
At Urbanfab, we believe proper protection starts with the steel itself.
That’s why we hot-dip galvanise our mild steel after fabrication, in accordance with ISO 1461:2022. The completed fabrication is fully immersed in molten zinc, creating a tough, metallurgically bonded coating that becomes an integral part of the structure.
Our products are engineered for effective venting and drainage, allowing molten zinc to reach and protect external surfaces, welds, joints and accessible internal areas of the structure.
'Galvanised' or 'Hot-Dip'? Check What's Supplied
The term ‘galvanised’ can refer to different zinc-coating processes, including pre-galvanised steel. The key difference is how and when the zinc is applied.
For large outdoor structural steelwork exposed to varying weather conditions, we choose post-fabrication hot-dip galvanising — a proven corrosion-protection method used extensively across construction, transport infrastructure and agriculture, where long-term protection of steel is essential to durability and service life.
Where hot-dip galvanising is advertised, separate coating terms that may not be immediately apparent on the product listing may allow alternative zinc treatments to be substituted.
Duplex ProtectionÂ
Many surface-applied paints and coatings rely on maintaining an effective barrier between the steel and its environment. When applied directly to unprotected steel, damage to this barrier can allow moisture and oxygen to reach the surface, increasing the risk of corrosion — particularly around joints, welds and areas exposed to persistent moisture or ground contact.
At Urbanfab, optional powder-coated finishes are applied over hot-dip galvanising to create a duplex coating system. The underlying galvanised coating provides long-term corrosion resistance and, if minor damage exposes the steel, the surrounding zinc offers sacrificial (cathodic) protection. The powder coat adds colour and a durable, UV-resistant protective barrier.
The Urbanfab Standard
We recognise that advanced multilayer coating systems, including Triplex systems, can offer strong corrosion resistance. However, our engineering principle remains constant:
Protect the Core First. Then Apply Surface Coatings.
The C1–C5 corrosivity classifications in ISO 12944 describe the severity of the surrounding environment. They do not, by themselves, determine whether every surface within a structure — particularly concealed or internal surfaces — has received an equivalent level of protection.
Long-Term Protection
Hot‑dip galvanised steel to ISO 1461:2022 provides long‑term corrosion protection, delivering an indicative service life of approximately 34 years — depending on atmospheric conditions across the UK. For information on optional surface finishes, see our Powder Coating guide.
For Urbanfab, hot-dip galvanising isn't simply a finish. It's how we protect mild steel for the future.
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