weathering steel

For almost a century, weathering steel has been used in bridges, fences, buildings, and even artwork. Its unique appearance and ability to avoid corrosion have made it a must-use for many construction and structural projects over the decades.

Even if you haven’t heard of weathering steel, the buildings and structures around your city or hometown have definitely benefited from its use. This article will go over how weathering steel was discovered and come to be as it is today, as well as its practical uses in everyday life.  

What is Weathering Steel?

Weathering steel is also referred to as Corten A or Corten B steel. It is an alloy steel that is often used in construction and is well-known for its rust-like appearance.

The outer appearance is actually a protective rust layer called a “patina” that inhibits further corrosion and extends the life and use of the steel. These steels are low alloy and have great strength due to their resistance to corrosion.

The Composition of Weathering Steel

Weathering steel is a low-carbon alloy. The low amount of carbon is what allows it to be tough and ductile. The three alloys in weathering steel are nickel, copper, and chromium.

While weathering steel can rust, it only does so on the outer surface. If the outer coating of rust has grown, the rust does not go further into the steel. The rust-coated surface serves as a kind of protective shield, preventing the steel from any additional corrosion.

The rust layer that is formed on the plain carbon steel is porous and breaks off, which allows it to form another layer deeper into the steel. The cycle continues until the regular steel is useless.

The first layer of rust on the weathering steel forms to hold on because of the contribution of alloys. Hence there is no need to coat the metal with a protective layer as it is self-protected through any sort of weather that occurs. You can, however, coat weathering steel in a protective coating to stop the rust from staining the surrounding areas as the rust will spread when rained on. 

The History of Weathering Steel

In the 1930s, the US Steel Corporation developed weathering steel to get the stronger, more durable steel they needed for the hopper carts to carry their ore and coal to the furnace.

Later they realized this metal alloy had useful corrosion resistance that could be marketed and sold in other industries, so the new alloy was trademarked and called COR-TEN® steel. 

The first time weathering steel was used for architectural purposes was at the John Deere World Headquarters in Illinois. This building was designed by famed architect Eero Saarinen, and the building was finished in 1964. 

Weathering steel is also used for artistic purposes. In 1977, Robert Indiana created a Hebrew version of the LOVE sculpture using weathering steel for the Israel Museum Art Garden in Jerusalem.

Many artists have incorporated weathering steel into their work since its arrival; the most well-known artist being American sculptor Richard Serra. Serra has built numerous, massive sculptures using weathering steel that can be found around the world.

The first weathering steel bridge was a footbridge built in 1967 at York University. It has been used in large bridge and structural applications around the world since. Some examples are the New River Gorge Bridge, the second span of the Newburgh–Beacon Bridge in 1980, and the Australian Center for Contemporary Art (ACCA) and MONA.           

It was also used in 1971 for the Highliner electric cars built by the St. Louis Car Company for the Illinois Central Railroad. Using weathering steel was seen as a way to cut costs in comparison with the pricey stainless steel that was the railcar standard. 

Companies such as MetalTech Global have vast experience in fabrication and artful design, which can be seen in such projects like:

  • Embry Riddle Aeronautical University in Florida
  • CREC Academy of Aerospace & Engineering in Connecticut
  • Los Angeles Trade Technical College in California
  • Owensboro Convention Center in Kentucky
  • Casa Val in Costa Rica
  • Chelsea Studios in New York

These examples show the range of what perforated metal can do in the hands of experts and talented artists and craftspeople. 

How Long Does Weathering Steel Last?

Because of its protective rust coat that provides corrosion resistance, weathering steel used in bridges, architecture, and other mediums can last upwards of a few decades to over 100 years in the proper conditions.

Get Quality Materials for Your Next Project 

MetalTech Global is the nation’s premier distributor and fabricator of coil, sheet, and finished architectural metals products. We promote the use of sustainable metal products in the buildings and are able to create custom perforated patterns and shapes as well. With high-tech tools and over 25 years of experience, our architectural support staff can realize an unlimited variety of folded and perforated panel designs.

Contact us today for all of your weathering steel, perforated metal, coil, panel, and fabrication needs! We hope to work with you today to realize your next architectural dream.

Metal Roof vs Asphalt Shingles

Whether you’re an owner looking to renovate, a customer looking to buy, or an architect planning a project, it’s no secret that there are a multitude of factors to consider when it comes to a house. One of the most important and most prominent factors to consider however is what kind of roof you ought to look for or install on a building. 

Traditionally, asphalt shingles have long been the standard, go-to roofing option in the United States, but increasingly they’ve faced more competition from metal roofing. Metal roofs can be made in a variety of materials (zinc, tin, aluminum, copper, or steel), but all metal roofs will tend to offer the same benefits and drawbacks when compared to asphalt shingling (the main difference between the various materials being price). 

This article will thoroughly explore all the factors one must keep in mind when deciding between Metal Roof vs Asphalt Shingles, and lay out the advantages and disadvantages of each choice. 

Pros of Metal Roofing

Low Maintenance 

Perhaps one of the greatest advantages of a metal roof is the fact that, once properly installed, they require almost no maintenance. Most roofing metals are highly resistant to damage, thanks to a protective patina that will self-heals minor scratches naturally over time. They are also antimicrobial, and won’t suffer from mold or algae, unlike asphalt shingles. 


Unsurprisingly, a metal roof is far more durable than a shingle one. While a shingle roof will generally need to be replaced every 25 years or so, a metal roof will generally last between 50 to 80. Apart from saving homeowners the cost and hassle of replacing a roof several times in their lifetime, longer-lasting products have a naturally positive effect on the environment, requiring less raw material and waste. 

Most kinds of metal roofs are also highly recyclable and can be melted down and reused once they reach the end of their natural lifespan. 

They Boost Home Value

Adding a feature to your home that’s durable and cost-saving in the long run is naturally a benefit to the building’s overall value.  This can increase the property’s value, and even potentially save on insurance, as some firms will offer lower rates to encourage a safe long-term investment. 

Cons of Metal Roofing

Limited Availability of Professionals

Although metal roofing is growing in popularity, it’s still distinctly in the minority compared to traditional shingles. This means that finding a reliable professional in your area with the expertise needed to install a metal roof can be challenging. 

Time and Labor Intensive

Similar to our last point, a metal roof requires specialized knowledge and tools to install, and because of this, is a more intensive process, requiring longer to install than shingles. 

Pros of Shingle Roofing


There can be no denying the benefit of being able to easily remove or replace broken or moldy tiles as needed. Even an informed non-professional can walk directly on their roof to do simple repairs on their own. 


Although a metal roof is a sound investment that will ultimately save money in the long run, the up-front cost of installing an asphalt shingle roof is objectively cheaper than metal. Sometimes, financial realities will demand the cheaper immediate fix of shingles. 


If finding a qualified, reliable professional to install a metal roof can be difficult, then naturally the opposite holds true for the single most common form of roofing in the nation. It will almost certainly never be hard to find a good professional at a reasonable price for shingle roofs. 

Cons of Shingle Roofing

High Maintenance 

Compared to a metal roof which can be “set and forget”, a shingle roof will need to be replaced sooner and will require regular maintenance. Whether it’s a hail storm, pests, algae, or just the passage of time, shingle roofs must be monitored and regularly kept in good condition. 

Environmentally Unsustainable

Unlike metal roofs which can be recycled at the end of their service life, asphalt shingles are a petroleum product, reliant on fossil fuels to be produced and very difficult (if not impossible) to recycle. 

Aesthetically Limited

Metal roofs, apart from being able to be designed in interesting and non-conventional forms, come in a variety of colors suitable for both historic and modernist looks. On the other hand, if you have seen one shingle roof, it could be said that you’ve seen them all. While singles are often aesthetically pleasing, they don’t exactly offer very much range or variety. 

Calling in the Experts

When it comes to architectural metal, there’s no more trustworthy and high quality name than MetalTech Global. As the nation’s premier fabricator and distributor of finished, coil, and sheet metal, we are home to the single largest stocking center for architectural zinc in the country. With decades of experience and an expansive portfolio of projects completed using our top-notch materials, we’re here to ensure that your next construction project is completed with only the best in expertise and service. Contact us today for a consultation on how we can help you reach your architectural goals.