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5 Problems With Corten Roofing (+An Alternate Solution)
Lauren Risotto

By: Lauren Risotto on April 17th, 2020

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5 Problems With Corten Roofing (+An Alternate Solution)

Corten Roofing | Metal | Problems

 Corten steel is popular as a roofing material for its striking rustic appearance and low maintenance. The rust forms a protective layer that slows down the overall rate of corrosion. However, there are some problems with this type of material which will not make it the right choice for every homeowner.

At Western States Metal Roofing, we specialize in metal roofing and siding in both Corten and metal painted panels. While Corten is an excellent product, we realize it’s not the right material for everyone to use.

We want you to be informed before making a buying decision, so we have compiled the biggest issues we hear from customers about Corten roofing. We also will discuss why painted metal panels might be a better choice for your project.

  1. Corten Does Not Have A Warranty
  2. Rust Run-Off
  3. Corten Should Not Be Used On Low Sloped Roofs
  4. Corten Is Not Compatible With All Climates
  5. Dissimilar Metals And Corten

When you buy Corten steel, you are buying a product that is designed to rust. This type of product is not warrantable. There is just no way to have a warranty on something that rust. Every climate is different and the longevity will be affected by the climate. If this is a concern then it’s the wrong product for your job.

However, if you still want the look of a rusted roof, but need a warranty there is an option. painted rusted roofing is a painted metal that is designed to look like an old rusted steel.

Rust runoff

If you have a rusty roof or wall you will have rust runoff. Rust runoff will likely stain the surrounding surfaces. It would not be a good idea to have a rusted roof or wall next to white concrete. A Corten wall also should not be in an area where people’s clothes would rub against it. This would lead to orange clothing. The only way to control rust runoff is the installation of gutters and downspouts. These will allow you to divert the runoff to a different location. The rust runoff will be more prevalent when the steel is new and will decrease as the rust matures.

The minimum pitch required to have a Corten roof is 3:12. This pitch will eliminate standing water from being on the roof for prolonged periods on a rusted roof. Corten was designed to go through wet and dry cycles. If you have standing water on your roof the Corten will not function correctly and it will rust through at a much quicker rate.

The idea behind rusted roofing is that the steel is allowed to rust and that rust forms a protective coating that slows the rate of future corrosion. Not all environmental conditions will allow this to happen correctly. There are some climates where you should not install a Corten roof.

Corten or bare steel is NOT recommended in areas that have:

  • High rainfall
  • Humidity
  • Persistent fog
  • Salt laden air

These environments can create a condition in which the rust layer never reaches a stable point. Over time, the steel can become perforated and may need to be replaced.

Corten should not be used with dissimilar metals. While stainless steel is compatible with Corten, metals such as Galvanized, Galvalume®, and zinc are dissimilar to Corten and should NOT come into contact with Corten.

Dissimilar metals coming into contact will result in one of the metal’s lifespan being decreased. This is the result of galvanic corrosion. When two dissimilar metals come into contact, one of the metals will experience corrosion at an accelerated rate.

Alternate Solution - Painted Rusted Roofing

If you’re discouraged by the potential problems that can arise with Corten, there is another option. Metal roofing panels that are painted to look rusted are designed to mimic the appearance of Corten while providing other benefits.

Painted Rusted Roofing Warranty

While there is no warranty on Corten, the painted metal panels include a standard limited paint warranty. The warranty varies between 25- 40 years depending on which color you choose.

Consistent Appearance

The finish of Corten may not be consistent throughout the entire roof or wall. Some areas may rust more than others. If one side of the building is exposed to the weather and another side is not then the finish will be inconsistent. However, painted panels are manufactured with an even finish to look like a real weathered roof. Painted panels also do not cause any rust runoff or staining to surrounding areas.

There are 9 colors available in our Painted Rusted Series. Each color reflects a color point in the rusting process.

Take The Next Step And Request A Free Metal Sample

The unique look of rust coupled with its naturally oxidizing finish makes Corten a tempting choice for roofing. However, there are some reasons why it might not be the best choice for your new roof.

You should not use a Corten roof if:

  • You are looking for a product that comes with a warranty
  • You want to know exactly how your roof is going to look
  • You are concerned with other areas, like walkways, becoming stained from rust.
  • You live near the ocean or in an area with high rainfall, humidity, or fog.

Instead, you may choose to use painted metal panels that look like Corten steel. These panels:

  • Replicate the look of a real rusted roof
  • Do not stain its surroundings
  • Can be used in most environments
  • Include a paint warranty

At Western States Metal Roofing, we have been manufacturing roofing products for over 20 years. We manufacture both Corten and painted metal panels.

We are happy to answer any questions you have about the differences between these products and assist in helping you choose the roofing material that is right for you. We can also supply you with a sample of both materials so you can compare them in person.

You really should look at either product up close. Metal roofing looks different online versus viewing in person. The detail in the paint is stunning and looks authentic. To get started, request a free sample and a member of our knowledgeable team will be in touch with you shortly.

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About Lauren Risotto

Lauren is the Content Manager at Western States Metal Roofing and provides insight on content creation and product promotions.