Preparing a deck for exposed fastener metal roofing starts with ensuring the sheathing is solid and suitable. This means using exterior-grade plywood or oriented strand board (OSB) that is properly spaced to allow some natural expansion and contraction, typically leaving a 1/8-inch gap between panels. The sheathing should be flat and free of any bumps or dips, as uneven surfaces can lead to problems with fastening and may cause noise or leaks later on. If the deck is old or patchy, it’s a good idea to replace or reinforce it to provide a stable foundation. When it comes to fasteners, you want to use screws specifically designed for metal roofing with neoprene washers, as these create a waterproof seal. Avoid nails for better holding power and durability. Screws should be long enough to penetrate through the deck by at least 1 inch for secure fastening.
A simple DIY check involves walking the roof while paying attention to any soft spots in the deck—these usually mean rot or damage underneath that must be repaired before installing metal roofing. You can also visually inspect for flatness, using a straight edge or level, focusing on known trouble spots like valleys or areas around chimneys. If you notice any significant unevenness or damaged sheathing, it’s best to address these before proceeding. If unsure, or if the deck has hidden damage, calling a roofer is wise. When talking with a contractor, ask “What type of sheathing do you recommend for exposed fastener metal roofing, and will it require reinforcement?” and “What fastener length and type do you typically use to ensure a watertight seal on decks like mine?” These questions help ensure the prep work meets both code requirements and warranty coverage for a long-lasting roof.