Fiberglass shingles are a popular roofing choice because they combine durability with affordability, but you might sometimes notice rust stains on or near them, which can be confusing. These shingles themselves don’t rust because they’re made from fiberglass and asphalt, materials that resist corrosion. Rust stains typically come from metal components around the roof such as nails, flashing, gutters, or vents that have started to corrode from exposure to moisture. This rust can then be washed onto the shingles by rain. The main causes are usually older metal parts that aren’t properly coated or have been damaged, allowing rust to form and run onto the roofing surface. Rust stains can also develop from metal debris left on the roof or from faulty flashing installations that trap water near metal fasteners.
If you notice rust stains, start by inspecting the roof and gutters for any visibly corroded metal parts. You can safely check with binoculars from the ground or use a sturdy ladder to get a closer look, taking care to avoid stepping on fragile areas of the roof. Clean off any debris and note whether the rust stains are near specific metal fixtures. If you identify rusty nails or damaged flashing, it’s often best to call a roofer, as replacing these components may require specialized tools and techniques. When discussing the issue with a contractor, ask whether they recommend using corrosion-resistant fasteners like galvanized or stainless steel nails and if they suggest inspecting the roof’s metal parts regularly to prevent future rust problems. These questions will help ensure your repairs align with warranty requirements and prolong your roof’s life.