Spray polyurethane foam (SPF) roofing is a unique system that requires a specific nail pattern and fastener schedule primarily when used in conjunction with a protective cover board or insulation board beneath the foam or as part of a retrofit assembly. The fasteners and nail patterns are designed to secure these layers properly before the SPF layer is sprayed. Typically, the nail pattern depends on the type of substrate, the size and thickness of the board, and local building codes, but generally, fasteners are spaced evenly in rows about 6 to 12 inches apart along the edges and the field of the board. This ensures the cover board remains firmly attached to the roof deck underneath, providing a stable, secure base for the spray foam application. Without proper fastening, the foam can have issues adhering or may become compromised by movement or wind uplift. To check this at home, look for the number and spacing of fasteners when inspecting the base layers during reroofing or new construction; uneven or sparse nailing could be a red flag.
If you’re doing a simple visual inspection yourself, make sure that the fasteners are consistent across the board edges and field, and look for any loose or missing nails before foam application begins. However, remember that the SPF layer itself is sprayed on and doesn’t involve nails or fasteners after application, so the schedule is more about what’s underneath. If you notice irregular fastener spacing or doubts about the attachment method, it’s wise to call a professional roofer experienced with SPF systems. When you do, ask them how they determine the fastener schedule for your specific roof type and if they follow manufacturer guidelines or local code requirements for uplift resistance. Also, inquire whether they use corrosion-resistant fasteners suitable for your climate and roof deck to ensure longevity and warranty compliance.