Corrosion, sometimes called rust, can be a very destructive force where metal roofing is concerned. However, when you're armed with the right information and perform the correct upkeep, you can reduce or avoid the potential for metal roof corrosion. Here's what you need to know about the relationship between metal roofing and corrosion or rust.
Which Types of Metal Roofs Are Susceptible
Although many metal roofs are made out of steel, some are made of zinc, copper, or aluminum. All these metals may react differently to different rust or corrosion triggers. Steel, for example, is highly susceptible to corrosion when it gets wet, which is why steel is typically galvanized (coated in other metals) before use on your roof.
Multiple Ways Metal Can Corrode
Although the most familiar type of corrosion, a basic brownish-orange rust, can be an unsightly problem, it's not the only way roof corrosion can occur. This typical rust occurs when a susceptible material gets wet and oxidation occurs. However, two other avenues of corrosion can also be relevant here: galvanic corrosion and corrosion from salt spray.
Galvanic corrosion, also called metal-to-metal corrosion, occurs when your metal roof comes into contact with an item that's made of a different, incompatible metal. For example, if your roof is made of zinc (or galvanized steel that has zinc in the coating), any nearby copper could cause corrosion.
One way this can occur is if your roofer uses metal fasteners or flashing that aren't compatible with the roofing material. However, other metal items such as HVAC units, pipes, gutters, installation brackets, and other items can also cause corrosion problems if they contact your roof.
Another situation that can cause corrosion is when your roof is constantly hit by a salty sea breeze or salt spray. The salt can enhance corrosion speed, which is why more corrosion-resistant metals such as aluminum are often recommended for beach homes.
Top Ways to Prevent Rust
Your first line of defense is to hire a contractor who's experienced in metal roofing specifically. This type of roofer will know which materials can stand up to salt spray, which materials are compatible and incompatible, which roofing accessories to look for when checking for incompatible metals, and which coatings to use to protect your roof.
Once you've found the best contractor, be sure to follow these tips as well:
- Schedule regular roof inspections and maintenance
- Don't let anyone walk on the roof except the metal roofing expert (scratching the surface of a galvanized roof, for example, could let rust in)
- Call your roofer anytime something happens that could damage the roof coating (such as a fallen branch or hailstorm)
These tips will help you keep your roof in shape and prevent unsightly rust and corrosion.
As you can see, metal roof rust and corrosion can be a bit more sneaky and complicated than expected. Contact a local metal roof service to learn more.