I just researched this, google;
"Best Practices for Snow Country
Panel Style: In heavy snow areas, concealed-fastener roofs (like standing seam) are highly recommended because they present a completely smooth surface and keep fasteners completely hidden from snow and ice.
Screw Placement: On exposed-fastener (screw-down) metal roofs, screws should always be driven into the flat pan of the metal rather than the ribs, ensuring the rubber washer sits flush to create a proper, leak-proof seal.
Snow Retention: If you are experiencing heavy snow buildup or sudden, dangerous roof avalanches, installing a properly engineered snow retention system is the most effective way to protect your roof's screws and fixtures from sudden shear forces."
I amazed at the problems you are having in North America with metal roofs.
"Understanding Snow and Fastener Interaction
Obstruction: The raised screw heads and their gaskets create microscopic ledges. As snow slowly shifts or melts down the roof, it catches on these hardware bumps.
Fastener Stress: As accumulated snow freezes and thaws, it expands and bonds to the roof. When heavy snow blankets slide down, the immense shear weight pulls directly on these screws, which can eventually cause fasteners to loosen or back out.
Leak Risk: Because metal roofs expand and contract with temperature changes, shifting snow and loose screws can degrade or crack the rubber washers over time, opening up entry points for water."
