When it comes to industrial roofing systems, the most common material used is metal. Why is that? Metal roofs are the lightest and most enduring roof materials. To begin with, they are completely non-combustible and therefore one of the safest exterior features you can put on a building. They also lower the roof weight and their maintenance are reduced to an absolute minimum, bringing them as close to a permanent roof solution as possible. Their inherent quality, however, does not negatively affect or take anything away from their appearance; in fact, due to the variety of materials and colors that are available they can suit any architectural style.

Metal Roofs are Energy Efficient

An added benefit, and very important in this day and age, is energy efficiency. Metal roofs are environmentally friendly and reduce energy use and cost, so they are called cool metal roofs. They can save money and also benefit the environment. The idea behind them is simple – they function in the way that reflects most of the sunlight and generally do not absorb heat as standard roofs do. Nearly any type of building can benefit from a cool metal roof and those benefits are numerous, including:

  • Reducing energy bills by decreasing air conditioning needs
  • Decreasing roof temperature, which may extend roof service life
  • Cool roofs can reduce the heat absorbed from the sun significantly – it’s not unusual for a dark roof on a hot, sunny day to reach temperatures of 160°F (71°C) or more. A cool metal roof, on the other hand, can easily be 50°F cooler, and the difference in the amount of heat transfer as a result can be tremendous.
  • Reducing the urban heat island effect, which is common in urban and industrial areas, by reducing the overall temperatures in that area
  • Reducing energy/electricity usage, which helps prevent power outages
  • Reducing the need for cooling in power plants, and therefore reducing their energy usage and emissions of harmful and toxic gases such as carbon dioxide or sulfur dioxide

Explaining the Causes of Metal Roof Corrosion

There is, however, one common problem with industrial metal roofs, but fortunately one that can be prevented. One of the main problems of industrial metal roofing systems is corrosion. It is well known that the main cause of corrosion is the presence of water. Since metal roofs are iron-based, and roofs are in general exposed to rain and moisture, it is very common and expected to encounter corrosion on them. Oxygen in the water and iron in metal roofs react and create corrosion, forming a layer of corrosion on the roof. This layer then spreads and attacks the metal causing further damage to the roof.

Asset Protection and Corrosion Prevention

When it comes to asset protection, the most important considerations are maintenance and prevention. (For more on asset protection and management, see What is Coatings Asset Management? Terry Greenfield Q&A.) Much like many other problems with roofs, corrosion can be prevented through regular and proper maintenance. The best and most common way to prevent corrosion is to apply a protective coating. This protective anti-corrosion coating functions as a barrier between the roof, or the metal on the roof, and the water that comes into contact with it. The possibility of iron oxidation is significantly or completely reduced and the roof will be safe from corrosion.

There are different types of coatings, and the one to use will depend on the substrate material of the roof. When it comes to metal roofs, substrates can be steel, aluminum, copper, zinc alloys or galvanized steel. The professional applying the coatings should know what type of substrate is on the roof and take that into consideration.

Another way to prevent corrosion is to also paint the roof with a primer. The best primer for corrosion prevention would be the one that contains at least 80% zinc. (Discover more in Duplex Coating: How it Works, How it's Applied) As with coating, painting should also be done correctly and regularly. The best schedule is to do it every three years, and always make sure the roof is cleaned and washed thoroughly before the primer and coating are applied.