Profiled Steel Repaint Guide


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Why Coatings Fail

There are many factors, which cause paint to deteriorate and delaminate. They include the intensity of sunlight, especially UV; the amount of rainfall and the time of wetness which particularly affects more permeable coatings and the quality of the pigmentation itself. Most paints must use primers to delay the onset of these effects.

Caught in time, most profiled steel sheeting can be treated without replacement, and its protection indefinitely preserved by re-painting.

Profiled Steel Roof

PVC Plastisol

A tough and durable 200 micron embossed finish coating, factory applied on a galvanised steel substrate. It degrades, like most paints, over a long period of time in three main phase changes affecting the sheet.

Phase 1: Appearance

Still adherent, UV and erosion cause colour fade and chalking, Check period remaining before the onset of Phase 2

Phase 2: Delamination

UV age-hardening leads to PVC micro checking or lift. Repainting is now required for continued sheet steel protection.

Phase 3: Corrosion

Where exposed, corrosion is now established on the steel substrate. Repainting may be still possible but replace sheet if perforated.

PVF2 (PVDF) & Polyester

These factory finished coatings were traditionally chosen for their excellent colour and gloss retention, increasingly wider patterns of erosion signals their end of life process.

Surface Erosion

Pvf2 & Polyesters are much thinner coatings than PVC Plastisol making them far more permeable and more inclined to break down and perforate from corrosion of the underlying steel. It’s important to remember not to just treat local patches of corrosion as the coating will progressively degrade as it reaches its end of life. Repainting is required for continued steel protection unless perforated when sheet replacement is required.

Giromax Corroded Roof


Giromax operate a series of Continuing Professional Development seminars on Profiled Roofing & Cladding refurbishment throughout the U.K. and Ireland.

The free 1 to 2 hour seminars are usually held over lunchtime at the clients’ offices and have proven to be particularly useful to both building surveying and architectural practices alike.