Understanding European Corrosion Ratings

June 6, 2024|In Featured

Commercial metal roofing is known for its durability and longevity. However, without the right maintenance and repair, metal roofs can succumb to the elements, leading to corrosion and eventual structural failure. One effective method of protecting and extending the life of metal roofs is with special liquid-applied systems.

European corrosion ratings, also known as corrosivity categories, are defined by the International Organisation for Standardisation (ISO 12944). These ratings help identify the potential for corrosion in various environments, guiding the selection of appropriate protective measures for metal structures.

Corrosive Categories

The corrosive categories a broken down into 6 different ratings

  • C1 - Very Low: Typically indoor environments where the risk of corrosion is minimal, such as offices and heated buildings.
  • C2 - Low: Mildly corrosive environments like unheated buildings where condensation might occur, including warehouses and sports centres.
  • C3 - Medium: Urban and industrial atmospheres with moderate sulphur dioxide pollution, or coastal areas with low salinity. Examples include breweries, dairies, and food processing plants.
  • C4 - High: Highly corrosive environments such as chemical plants, swimming pools, and coastal areas with moderate salinity.
  • C5-I - Very High (Industrial): Industrial zones with high humidity and aggressive atmosphere, such as areas with frequent exposure to chemical fumes and high levels of pollutants.
  • C5-M - Very High (Marine): Coastal and offshore areas with high salinity, which are particularly aggressive toward metal surfaces.

Special Categories

  • CX - Extreme: Extreme environments with almost constant exposure to high humidity and airborne pollutants, such as offshore structures and industrial areas with aggressive atmospheres.
  • Im1, Im2, Im3 – Immersion: Categories for metals in water or soil, relevant to submerged structures.

Implications for Metal Roofing

Metal roofing, especially in commercial settings, is often exposed to harsh environmental conditions that can accelerate corrosion. Understanding the specific corrosivity category of a given environment is crucial for selecting the right protective measures.

Liquid-applied roofing systems provide an effective solution for protecting metal roofs against corrosion. These systems involve the application of a liquid membrane that cures to form a seamless, durable, and waterproof barrier. The benefits include:

  • Seamless protection: Eliminates weak points in the roof where water and contaminants can penetrate.
  • Flexibility: Can expand and contract with the metal roofing, preventing cracks and leaks.
  • Versatility: Suitable for various environmental conditions, tailored to meet specific corrosivity categories.

Linking corrosion ratings to metal roofing

In environments classified under the C5 corrosion rating, the demands on protective measures for metal roofing are at their highest. These areas, whether industrial (C5-I) or marine (C5-M), are characterised by extreme corrosivity due to high humidity, aggressive pollutants, or high salinity. To ensure your commercial metal roof can withstand these harsh conditions, it is essential to use a roofing system that meets these rigorous standards.

Our liquid-applied roofing systems are certified to the C5 standard, providing exceptional protection in the most challenging environments. This certification assures you that our system has undergone stringent testing and meets the highest criteria for corrosion resistance.

The C5 certification means that our systems are specifically designed to withstand high humidity and salinity, making it ideal for anything the British weather can throw at it including coastal and offshore environments where salt spray can quickly corrode unprotected metal surfaces. It also resists aggressive industrial pollutants, making it perfect for industrial zones where chemical fumes and high levels of pollutants can accelerate the corrosion process. It also provides long-lasting protection by forming a robust, seamless barrier that prevents water ingress and shields the underlying metal from corrosive elements.

By choosing our certified C5 liquid-applied roofing system, you are investing in a solution that not only meets but exceeds the requirements for extreme environments. This ensures your metal roofing remains durable and performs optimally, significantly extending its lifespan and reducing maintenance costs. Incorporating our certified C5 liquid-applied system guarantees the highest level of protection, enabling your metal roof to withstand the toughest conditions.

For more information on how our C5-certified systems can benefit your metal roofing needs, please contact us today or request a free site survey.