How To Paint Metal Exterior Surfaces

Exterior metal surfaces present unique challenges for homeowners. Metal outside your home is a necessity and needs protection from the elements. You may be asking yourself, how do I paint metal exterior surfaces?

Exposed metal is subject to water and thus, rust. One way to counteract the potential breakdown of your outside metal is to paint it. This will provide a protective layer on top of the metal and potentially slow or halt the rust.

Keep reading for our tips on painting metal exterior surfaces such as steel and aluminum…


It’s important to keep water and air off of your steel. Here is how to create a protective barrier with paint on steel.

  1. To paint or repaint steel, run a wire brush over any areas where rust may be or has developed.
  2. Get a speciality primer from your local paint store. It will state on the can that it is rust-inhibitive. Applying two coats, with drying time in between, will create an extra strong protective layer.
  3. Apply your paint. It’s suggested to use 100% acrylic latex or oil-based paint.

Spray Painting

A good option for steel is spray painting. Follow all directions from the can. If it’s possible, remove the project and place it on a work bench where you have access to the sides for an even finish. Short, fluid strokes will provide a solid finish.

DTM Paints

Some paints are sold as a Direct To Metal, or DTM paint. They are specially formulated for application on metal without a primer.

Aluminum and Aluminum Siding

Aluminum siding can chalk or wear down if you live in a harsh climate. Refresh your home without a full residing by painting exterior metal.

  1. Make sure the metal is clean and dry. Remove any dirt, grease or stains.
  2. Cover nearby areas to avoid getting paint on it.
  3. Prime the metal with anti-rust primer. This will create a good surface for adhesion and prevent future rust breakouts. Allow full dry time.
  4. Use a rust-preventative enamel on top. Apply several thin coats and allow to dry completely.

Aluminum and aluminum siding can be painted with good results, but there are a few issues that can happen.


Chalking can happen when the coating is very weathered. You know you have chalking going on when you run your fingers over a piece of your siding and it comes off white. Use a cleanser like trisodium phosphate before you start your project.

Finish suggestions for aluminum siding are to use a flat or satin finish paint. A glossy finish will typically accentuate any dings. Since aluminum can be more prone to dents, a flat paint will hide small imperfections.


Since siding is not able to be removed for painting, be conscious of nearby items. Put down a tarp or drop cloth to protect nearby bushes, ground or plants. Also be sure to take windy conditions into account, and any overspray that may overreach your drop cloth.

Need some help with your exterior painting project?

CertaPro Painters® of Southlake, TX is a locally owned and operated painting company based in Colleyville. Schedule a free, in-home estimate with our team to discuss your plans.

Exterior painting siding