The Uncompromising Standard
Hot-Dip Galvanising for Superior Structural Protection
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’ Does Not Always Mean Hot-Dip Galvanised
Where a product is described as simply ‘galvanised’ without specifying the standard or level of protection, the term alone does not tell you which galvanising or zinc-coating process has been used, or what coating specification applies. Alternatives may include pre-galvanised steel or other zinc-coating methods.
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.
Duplex Protection
Many surface-applied paints and coatings rely on maintaining an effective barrier between the steel and its environment. When this barrier is damaged, moisture and oxygen can reach the steel, increasing the risk of corrosion—particularly around crevices, 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 an enhanced duplex coating system. The zinc-iron layers formed during galvanising provide long-term corrosion resistance and sacrificial (cathodic) protection, safeguarding areas where powder coating may be inaccessible. The powder coat then adds a durable, UV‑stable environmental barrier, enhancing appearance while reducing weathering.
The two coatings work in synergy to extend service life: the powder coat forms a colour-stable environmental barrier that shields the zinc, while the galvanised layer continues to protect the steel wherever the outer finish is damaged. Together they deliver elevated long‑term performance, corrosion resistance and a refined architectural finish.
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 Treatments and Finishes.
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 — and often significantly more — depending on atmospheric conditions across the UK.
For Urbanfab, hot-dip galvanising isn't simply a finish. It's how we protect mild steel for the future.
