A green roof combines a layer of vegetation planted over waterproofing on a flat or slightly sloped roof. While green roofs are designed to protect the roof and improve energy efficiency, moisture and organic material buildup can sometimes lead to rusting, especially on metal components like flashing, fasteners, or structural parts. Rust happens when metal is exposed to prolonged moisture and oxygen, a common scenario under dense plant layers where water tends to stay longer. Poor drainage, inadequate waterproofing, or damage to protective coatings can accelerate this process. Simple diagnostics include visually inspecting metal areas for reddish-brown discoloration, flaking, or rough texture. You can also gently touch surfaces to check for softness that indicates corrosion underneath. A basic safe DIY check involves carefully lifting some soil or vegetation near metal edges and inspecting for standing water or moisture trapped against metal parts. Avoid using any harsh chemicals or tools that may damage waterproof layers.
If you spot rust or suspect metal deterioration on your green roof, contact a professional roofer with experience in green roof systems. It’s essential to address the root causes—often drainage fixes or replacing damaged flashing—to protect both the plants and the roof structure. When you reach out to a roofer, good questions to ask include: “How do you assess and maintain waterproofing in existing green roof setups?” and “What methods do you recommend for preventing rust in areas where metal components are exposed to moisture?” These questions help ensure the contractor understands the specialized nature of green roofs and can provide solutions that won’t void warranties or compromise the plants’ health. Proper maintenance will keep your green roof thriving and your metal elements rust-free for many years.