How to Paint a Galvanized Corrugated Roofing Sheet

Place a ladder next to the roof securely and climb up carrying a garden hose with a sprayer attachment. Spray the entire surface of the roof thoroughly from the top down to rinse away dirt and debris.

Scrub the roof with a damp long-handled scrub brush to remove tree sap and other stains. If needed, spray a degreasing cleaner or white vinegar on tough spots and scrub with the brush. Rinse the roof again with the garden hose.

Wait until the metal roof is completely dry. Position a paint tray on the tray attached to the ladder and pour an exterior-grade rust-inhibiting primer into it. Screw an extension pole onto a paint roller and install a rough roller cover with a nap between three-quarters and 1 1/4 inches. Apply the primer to the roof, rolling in slow motions to allow the longer nap to penetrate the grooves of the metal. Continue until no portion of the metal is visible.

Wait 24 hours for the primer to dry. Pour an exterior-grade acrylic or latex-based paint into a clean paint tray. Install a fresh rough roller cover with a long nap and roll the paint onto the surface of the roof, again using slow movements to ensure coverage of the deep grooves. Allow the paint to dry overnight and apply a second coat.