Scrub the damaged corrugated metal with a wire brush to remove dirt, grime and rust. Sweep the area thoroughly with a whisk broom to remove all loose debris from the area.
Dampen a clean rag with water. Wipe the damp rag over the damaged area to provide a clean surface for the repair. Dry the area thoroughly with a clean towel.
Cut two identical square patches out of roofing mesh, using metal shears. Wear safety glasses and leather gloves for protection against the metal particles. Make both patches large enough to completely cover the damaged area.
Spread a thick layer of urethane roof cement over the damaged metal, using a putty knife. Press a mesh patch into the roof cement. Follow the wavy contour of the corrugated metal.
Spread a thick layer of roof cement over the mesh patch. Work the cement into the mesh patch and undercoat, using the putty knife. Press the other mesh patch into the roof cement, following the wavy metal outline.
Spread the final layer of roof cement over the mesh patch. Press the cement into the mesh patch with the putty knife. Smooth the cement with the putty knife to create a uniform appearance.