Durability and performance is always synonymous with metal roofing for Denver CO homes. While they can last for more than 70 years and perform better than other roofing materials, they’re not flawless. In fact, it’s not always the case that you should use steel or aluminum-based roofing material for your property just because you can do so because of the risk of metal roof corrosion.

Salty environments in Denver CO — which involves living near beaches or salt factories — can cause immediate metal roof corrosion. This will significantly affect the overall lifespan and durability of the roofing material. In fact, according to Poma Metals, if you’re living 50 miles away from a high salt air environment, your metal roof corrosion risk increases.

Metal Roof Corrosion: How Far Inland Does It Travel?

In the map above, the rate of corrosion falls off at about 30 to 50 miles inland. Note that the map measures general corrosion rates for zinc-coated or galvanized steel. So the corrosion shows not only the effects of salt, but also industrial and urban pollutants. For this reason, you’ll see higher corrosion rates in more polluted industrial cities. Industrial areas such as Liverpool and Manchester get hit harder. (See the table below for more info on atmospheric pollutants.)

The map above gives a detailed view of coastal corrosion distance rates for metal. But what about the United States? Our company is based in Palm City, Florida. Due to wind speeds and other factors, this area is one of the most salty regions in the world. So we wanted to share a resource for understanding salt in local coastal regions. We researched the data for chloride-laden (salt) air in the USA and compiled the results below. (Continued)

As one of Denver CO’s finest roofing contractors with in-depth metal roofing experience, we often recommend using aluminum metal roof to prevent corrosion in high-salt areas. However, we only recommend this if you definitely want the aesthetic aluminum and metal roofs can provide.

Aluminum is highly resistant to corrosion. On the other hand, aluminum does corrode when it encounters saltwater. However, its corroded layer acts as a shield against further corrosion of the roofing materials. Aluminum Handrail Direct has an excellent explanation how this happens. Read more about it below.

How Aluminum Deals With Corrosion

Gold, silver, platinum, and a few other metals are found in their metallic state in nature. They’re the exception. Most metals naturally exist as minerals. For example, aluminum is created when a mineral called bauxite is mined, crushed, processed, and smelted. Because the metallic state isn’t their natural state, most metals are inherently unstable at a chemical level. When exposed to the environment, they tend to oxidize, which allows them to revert to their mineral form. This chemical reaction is corrosion, and its result varies depending on the metal and the environmental factors acting on it.

Aluminum actually does an excellent job of resisting corrosion, and when aluminum does corrode, the thin coating of aluminum oxide that forms as a result creates a protective shield that inhibits further corrosion. However, salts are extremely corrosive. When salt air and salt water come into contact with aluminum they can cause both the chalky, white coating of aluminum oxide and unpleasant pitting. Fortunately, there’s an easy way to protect aluminum from salt water and prevent unsightly corrosion: a powder coating.(Continued)

Lastly, metal roof corrosion doesn’t only happen with high salt air environments. It is possible that the wood on your home or the roof deck itself can play a role in accelerating its degradation. Copper, which is found in preservative-treated lumber that extends the lifespan and durability of wood, will reduce the capability of your metal roof through corrosion.

Metal Construction News has an excellent explanation on how this happens. In fact, this is a short excerpt from their completely-detailed white paper on the subject.

Copper-Coated Lumber and Metal Roof Corrosion

Corrosion of metals in an aqueous environment is an electrochemical process involving two steps. Water and oxygen must diffuse to the metal surface,and the reactants must have enough energy to complete the reaction. Some of the preservative chemicals bond to the wood, and a small percentage of them remain in ionic form in the wood. The ionic components increase the corrosiveness of the wood product toward metal. At higher moisture contents, wood conducts electricity and ions better, and therefore, the corrosion reaction occurs at a faster rate. It is believed that corrosion activity within wood requires a moisture content of 20 percent or greater (Flynn, K., Quarles, S., and Shelly, Jl, “Non-Biological Deterioration of Wood,” Forest Products Laboratory, University of California, 1995).

Many of the new preservative formulations contain twice as much copper as CCA. Copper ions can accelerate the corrosion of steel and aluminum.The potential for corrosion of hardware in contact with treated wood occurs when metals in the preservative (such as copper) are different from the metals in the hardware (aluminumor the iron in steel). In a wet environment these dissimilar metals create a small electrical current that triggers a chemical reaction resulting in galvanic corrosion. This is the challenge in selecting proper fasteners and connectors to be used with pressure-treated wood. (Continued)

Metal roofs do provide exceptional protection for any property for the longest time. However, Denver CO homeowners must also look to alternatives when dealing with metal roof corrosion. In addition, they must consider working with exceptional roofers to help achieve excellent installations for all kinds of roofing material. If you have yet to find a roofer, you can trust Ropa Roofing to help you with your roofing needs. Contact us today to know more!