The Best Way to Paint a Metal Roof

By Tuesday Fuller

The best and safest way to paint a metal roof is to hire a professional to do the work in a safe, convenient, and timely manner that will not damage the appearance and structural quality of the existing roof. Unfortunately, those funds needed to hire a professional are not always readily available. Therefore, for those considering a do-it-yourself approach to painting the metal roof, there are some things to know that will help you along the way.

Safety

Safety is always a huge issue to deal with when considering any roof jobs. Metal roofs in particular can be very slippery and sometimes, depending on the angle of the roof, might require special footing braces. Consider using a safety harness secured to a reliable stable section of the roof to prevent falls. Always work with a partner on the roof as well as an extra person on the ground to call for paramedics in case of an emergency. Always wear protective gear when working with chemicals such as acid cleansers and bonding agents.

Cleaning the Surface

First, evaluate the quality of the metal roof. Check for rust, mold and any tears or seams that might need fixing. Scrape off any old paint and rust with a flat-blade scraper, taking care not to gouge the metal surface. After you have removed all the rust, brush on a layer of trisodium phosphate cleanser, available at home improvement stores, to remove any mildew, mold, grease and residues left from the old paint. Using a high-powered pressure washer with a 3500-psi tip, thoroughly clean the surface of the metal roof. This step will help the TSP cleaning solution and will remove any leftover rust flakes.

Repairing the Surface

Repair the surface if there is evidence of any tears, cracks or leaking. To repair large holes, patch the hole with a piece of the same material as the roof. Cut a piece to fit into the damaged area, flux the edges that touch the existing roofing and insert the piece into the space. Next, secure and flatten the patch with weights and, using a soldering torch, heat the edges and apply solder to the seams. For a quick repair, or to create a supportive area for areas that change pitch or surrounds gutters, coat the area with roof cement and lay a piece of metal mesh on top. Apply a second coat of cement with a flat blade, working the cement into the mesh and lay another piece of mesh over that. Finally, coat the entire section with roofing cement and allow this to dry. Be sure to work neatly to avoid garish marks that show through the new top coat of paint.

Painting the Surface

Coat the surface of the metal roof with a rust-inhibiting primer designed for outdoor metal applications. When selecting paint top coats, take note of your local weather conditions since paints provide different levels of protection in different climate conditions, and always refer to the manufacturer’s directions for use. Refer to the manufacturer’s label for information that describes how many layers of paint are required to create a dry film thickness that will resist weather and water damage. If you are unsure of what brand to use, ask a trained paint store associate for help.