This is my boat shed. I noticed that the purlins are getting a bit weathered and finally figured out that water is migrating from that top edge. And migrating all the way more or less to the back. It's a single pitched roof and the picture is the top edge overhang. Some simple cheap way I want to lay some sort of drip edge along there to keep water from migrating down the underside of the tin . Any brilliant ideas that Re agreeable with that corrugation?