I do have plywood roof first then put the corrugated roofing on top of the plywood. Maybe that is the difference.We do have some of the worse winds. It has taken then vinyl siding off my house 3-4 times. Mine has never leaked and been on there 2-4 years. I don't put the nails real deep. I used the special nails that is for this roofing. The rubber washers on these nails are pretty think.
We had high 90's and 100 degree weather last year and our humidity is always very high in the summer.
Jim
That could be my problem, mine is nailed to the 2x4s and so the wind can probably make it vibrate some. we have a lot of wind here blows most all the time, but I do like it might have to see if I can repair it somehow with some type of wood bracing. This barn was built when we bought the house so we didn't have a say so in the building but it does have the rubber washers on the nails. Always something to fix around here.