Here’s a simple way to help prevent metal roofing from being blown away. Roofs are typically quite vulnerable to uplift in windy areas. There are commercially available roof hold-downs that bolt trusses and rafters to walls, but I’ve never seen the system described here. It was inspired by hearing all the stories about metal roofing blowing off in Haiti. (Apparently it’s routine to reattach metal roofing after major wind storms.)
This hold-down system is low cost and simple. It consists of 1/4″ x 3/4” flat galvanized steel bars bolted to purlins. Drill bolt holes at the top of corrugations. Use rubber washers to prevent roof leaks. (Insert rubber washers below the bars.) The drawing shows hold-downs located at the top, bottom and middle of each 8’ long sheet of roofing. Adjust the spacing between hold-downs for your region. The higher the wind speeds, the closer the spacing.