Corrugated metal roof panels are lightweight and remain sturdy for decades if properly handled and installed. The handling is especially important for galvanized corrugated panels, which can rust if the galvanized zinc coating on the panel is scratched or removed. The cutting methods used to cut a corrugated panel to length can often damage the protective coating along the cut edge; therefore, the less destructive the cutting method, the longer your corrugated metal roof will last.
Place a corrugated metal roof panel flat on a sturdy work surface.
Stretch the tape measure along one edge of the corrugated panel and mark the length you need to cut the panel with the permanent marker.
Set the combination square to the mark you placed on the panel.
Rest the permanent marker on the edge of the combination square blade and drag the combination square along the edge of the corrugated panel to mark a cut line on the panel's surface.
Align the cutting blades of the power shear with the cut line you placed on the surface of the corrugated panel, and pull the trigger of the shear to start the cut.
Push the power shear across the surface of the corrugated panel until you have cut the panel to length. If the power shear binds, tilt the handle of the power shear forward, toward the cutting blades, to change the angle at which the blades meet the surface of the panel.