Galvanized metal roofs show signs of corrosion with exposure to the elements. Although a layer of zinc is bonded to the steel to form a layer of protection, rust does develop. The advantage to the metal roof is longevity. Proper maintenance keeps a galvanized metal roof in good repair for many years. To keep a metal roof in good serviceable condition, inspect the roof twice a year and repaint every two to four years. Painting a galvanized metal roof keeps rust and corrosion from deteriorating the surface.
Step 1 – Scrape the metal roof to remove any loose paint, debris and rust. Clean stains and heavily soiled areas with a pressure washer or wire brush. Apply a mixture of 1/2 cup trisodium phosphate and 2 gallons of water with a paint roller. Rinse the roof with clean water and allow to dry.
Step 2 – Inspect the roof for damage. Repair any leaks with butyl tape or urethane roofing cement. Reseal around chimneys, roof vents and other areas of concern. Replace damaged closure strips. Use metal screws with rubber washers to prevent leaking.
Step 3 – Apply an exterior metal primer, made for galvanized metal roofs, over the entire surface. Use the manufacturer’s recommended application method located on the container of primer. Allow the primer to dry completely before painting.
Step 4 – Paint the galvanized metal roof with an exterior metal roof paint using a paint roller. Use a paintbrush around chimneys, spouting and other small spaces. Allow the paint to dry completely.
Step 5 – Check for uneven paint applications or areas you may have missed with the first coat of paint. Apply a second coat of paint, if necessary, to produce a uniform painted surface.