Constant freeze/thaw cycles cause expansion and contraction on metal roofs. This expansion and contraction loosens the seams and the fasteners, allowing moisture (water) to enter these critical areas. Negative pressure also allows the moisture that settles on the roof to be sucked in through these openings.
The solution: Topps RivetGuard! Tighten all fasteners and apply this rubberized sealer to the head of each fastener as well as coating all seams to end leaks.