When installing an exposed fastener metal roof, choosing the right underlayment is essential to protect your home from moisture and ensure the roof’s longevity. Exposed fastener metal panels are secured by screws visible on the surface, which can create potential paths for water to seep through if the seal deteriorates. A high-quality underlayment acts as a waterproof barrier beneath the metal panels, providing an additional layer of protection against leaks, especially during heavy rain or snow. Common choices include synthetic underlayments that offer excellent water resistance, breathability, and durability compared to traditional felt paper. These underlayments also resist tearing during installation, which is important for maintaining a continuous barrier beneath the metal. The right underlayment supports the metal roof's warranty by preventing moisture buildup and potential corrosion, helping your roof to perform better over its lifespan.
To diagnose whether you need a better underlayment under an existing exposed fastener metal roof, look for signs such as interior water stains, rust around fasteners, and loose or damaged panels, especially after storms. You can perform a simple visual inspection from the attic or inside the roof deck if accessible, checking for damp spots or mold growth. It’s safe to do these checks yourself, but avoid climbing on the metal panels, as the surface can be slippery. If you spot issues or if your roof is older than 15 years, it’s wise to call a professional roofer. When contacting a contractor, ask them what type of underlayment they recommend for your exposed fastener metal roof and why, and whether their choice complies with your metal roof manufacturer’s warranty requirements. This ensures your roof system is both sound and protected for years to come.