What qualifies for a fortified roof?

Five things have to be in place for FORTIFIED Roof certification (the IBHS hurricane-resilience standard). The deck has to be attached with 8d ring-shank nails in a 6/6 pattern (every 6 inches on edges and inside). Every deck seam has to be taped or fully covered with a self-adhered underlayment to seal water out. The drip edge has to be wider than code, with a fully adhered starter strip. The roof cover (shingle, metal, or tile) has to meet impact-resistance ratings. Attic vents have to be wind-and-rain rated. An IBHS evaluator inspects during install and issues the certificate.