Things You'll Need
Plastic putty knife
Galvanized metal etching primer
Latex exterior house-paint
HVLP paint sprayer
Paint roller extension pole
Steel siding lasts for years with a minimal amount of maintenance required to preserve both the look and protective properties of the material. Over time, however, even the best of maintenance can fail to prevent paint peeling from the siding. This makes siding look old and worn, though it remains structurally strong. Stripping away the entire painted surface can be both messy and time consuming. As an alternative, you can remove the peeling areas only, then repaint. With the application of a new paint layer, you can return the siding to its original appearance.
Check all the steel siding panels for any loose nails. Hammer all into place, making sure all are flat to the siding panels. Be careful not to nail too tightly and create dents in the panels.
Clean the steel panels with a pressure washer. Place a low-pressure tip onto the washer. Set the washer to low, then direct the water flow over the panels, working along each panel length to remove any dirt or debris. If you begin to strip away the peeling paint, then reduce the pressure before continuing. Wait two hours for the siding panels to dry.
Place a line of dropcloths along the base of the panels. Remove the peeling paint from the siding with a plastic putty knife. Scrape away the loose paint until you come to a section where the paint remains adhered to the siding.
Sand the remaining paint along the edges of the paint and siding. Use 120-grit sandpaper attached to a sanding block to sand the edges smooth, creating a seamless transition between the painted sections and the bare metal where you scraped away the loose paint.
Cover any trim, windows or doors adjacent to the steel siding with masking paper held in place with masking tape at the edges to prevent overspray of paint.
Brush a coat of galvanized metal etching primer over the exposed metal with a paintbrush. The primer creates a base for holding the topcoat of paint. Wait four hours curing time for the primer before continuing.
Thin a batch of latex exterior house paint with a compatible paint thinner until it is of a consistency usable for an HVLP paint sprayer. The HVLP sprayer manufacturer provides thinning ratio recommendations. Fill the paint sprayer reservoir with the thinned paint up to the fill line marked on the container.
Paint the steel siding panels using the sprayer. Aim the sprayer nozzle directly at the panels, eight inches from the siding surface. Trigger the sprayer to begin the paint flow, and use a back-and-forth motion to cover the length of the panel with an even coat of paint. Remove any overspray-caused paint runs caused by overspray with a piece of cloth before, then spray the wiped section again to even it out with the rest of the panel.
Roll the sprayed paint into the panel with a paint roller to seal it in place. After brushing, move the next panel and use the same process to apply the paint. Allow the coating to dry for two hours, then spray on a second coat to build up the paint layer and even out the coverage of paint along the entire surface. Wait two hours additional drying time. Search for any indications of the old surface showing through the two coats. If you can see the old paint, then spray an additional layer. Wait 24 hours for the final coat to dry.
Remove the masking and the dropcloths to complete the painting.
Wear a face mask during the paint removal and painting process. You want to avoid inhaling any paint chips during removal or fumes as you apply the new paint.