Preparing a deck for 3-tab shingles involves creating a smooth, solid, and well-secured surface to ensure proper installation and longevity of your roof. Start by inspecting the sheathing, which should be plywood or oriented strand board (OSB) that’s at least 7/16 inch thick and in good condition without any rotting or soft spots. The deck needs to be clean, dry, and flat because any bumps or dips can cause issues with shingle alignment and water drainage. Fasteners like roofing nails should penetrate the sheathing fully and be corrosion-resistant to prevent rusting. You might want to replace any fasteners that are loose or missing to provide a strong base and avoid future problems. It’s important to check the flatness by sighting down the roof from peak to eaves or using a straightedge; the surface should not deviate more than 1/4 inch over a 10-foot span. If it does, additional shimming or replacing damaged panels might be needed for an even surface.
For a straightforward DIY check, walk carefully across the deck to feel for any soft spots or squeaks indicating weakened sheathing or insufficient fasteners, and use a flashlight on the underside of an attic to inspect for daylight gaps between boards. However, when dealing with deck irregularities or multiple layers of old roofing materials, it’s safest to call a professional roofer. When you do, ask specifically how they will ensure the deck’s flatness and which type and gauge of fasteners they recommend for warranty compliance. Another good question is how they handle decking that doesn’t meet local building codes or manufacturer guidelines—will they replace it or take other corrective steps? Making sure these aspects are planned out will help your shingles last longer and maintain the warranty.