What determines wind rating for metal roof?

I live on the coast of NC and have a 4 year old home with a standing seam galvalume type roof. I lost several sections during hurricanes Matthew (75 mph) 2 years ago and more recently Florence (100 mph). In each instance I suffered water damage to interior of home, ruining drywall, baseboards, and hardwood flooring. My wife is ready to rip the metal roof off and replace with shingles as none of our neighbors with asphalt roofs suffered any damage. Why do we keep experiencing loss of roof panels when I've read that metal roofs are good to 140 mph?

I think it likely has to do with intallation. The anchors are spaced every 32", which seems awfully far apart for a waterfront home that will be exposed to hurricanes. Also, I noticed the anchors don't start close to the end of the panels, which would seems to make uplift more likely. Thoughts?

Does panel thickness play a role? The anchors are still attached to the roof but the panels tore off? Does this mean the material is too thin (.032")?

Please help!

Todd,

32" is too far in my opinion on a coastal application. Metal roofs, installed properly, are the roof of choice in storm applications.

It sounds to me that this is an issue having much more to do with a poor installation than anything with regards to the product.

0.032 aluminum would be a normal thickness and should not be experiences these blow offs and damage assuming it is installed properly.