Failing Paint Coatings and Environmental Causes

During a recent site visit to assess a major public car park, we surveyed approximately 25,000-30,000m² of structural steelwork and found widespread coating breakdown. There are many reasons that paint coatings fail: whether that be environmental conditions, poor surface preparation, lack of upkeep etc. This site visit perfectly demonstrated the effects of a ISO 12944 C4 environment on steel coatings. Large areas of the existing paint system had lost adhesion, leaving steel exposed to the elements and showing significant corrosion. The scale of deterioration highlighted the extent to which protective coatings can quickly fail.

Car parks are particularly harsh environments for paint systems. Steelwork is constantly exposed to moisture, road salts carried in by vehicles, vehicle exhaust emissions, and repeated temperature changes. These conditions gradually weaken ageing coatings. Once corrosion begins, it spreads beneath surrounding paint, causing blistering, cracking, peeling, and heavy rust staining. Over time, the structural steel can deteriorate far beyond what is visible on the surface.

Early inspection is essential in environments like public car parks. A detailed survey allows the extent of coating failure to be mapped and understood before deterioration becomes critical. It helps determine which areas need full removal of failing coatings and which may be suitable for localised repair, as well as identifying the right preparation methods and coating system for long-term durability. Simply applying new paint without addressing corrosion and preparation rarely solves the problem and often leads to more failure.

With the right approach, structural steel can be protected for many years, reducing long-term maintenance costs and ensuring the safety and appearance of heavily used public spaces.

Failing coatings are often an early warning sign that a structure needs attention. If paint is peeling, blistering, or showing rust staining, a professional inspection can identify the root cause and help plan effective remedial works before the damage escalates.