Aluminum is a popular roofing material because it doesn’t rust in the traditional sense the way steel does since it forms a protective oxide layer on its surface. However, aluminum can still corrode, especially when exposed to water and certain environmental conditions. If aluminum comes into contact with rusted steel or other metals, or if there’s acidic runoff, it can develop white, powdery corrosion known as aluminum oxide. This corrosion weakens the metal over time and can cause leaks or structural issues if left unchecked. Simple DIY checks for this include visually inspecting the metal panels or flashing around your roof for any white, chalky spots or stains adjacent to rusty steel fasteners or gutters. You can also gently rub these areas with a soft cloth to see if powdery residue comes off, which is a sign of corrosion.
If you notice such signs, it’s usually safe to clean the affected area with a soft brush and mild soap solution, then rinse thoroughly and dry. Avoid using harsh chemicals or steel brushes, which can damage the protective oxide layer. However, if the corrosion appears widespread, if panels feel brittle, or if you see rust stains spreading onto aluminum components, it’s time to call a professional roofer. They can assess if any sections need replacing and whether the fasteners or flashing should be upgraded to compatible, non-corrosive materials. When you contact a contractor, ask specifically about the type of metals used and whether they offer aluminum-compatible fasteners or coatings that prevent galvanic corrosion. Also, inquire if their repairs preserve your manufacturer’s warranty, as improper materials or work can void it.