How to Prepare Exterior Surfaces That Have Peeling Paint for New Paint

Proper surface preparation extends the life of exterior paint.

Ten percent of all paint jobs have problems, according Sherwin Williams Co. technical manager, David Chupka. Save time and money by properly preparing surfaces prior to applying new paint, particularly if existing paint is already peeling. This includes diagnosing any moisture problems that are causing the paint to peel, removing the peeling or flaking paint and priming the surface.

Things You'll Need

• Paint scraper
• Power washer
• Step ladder, extension ladder or scaffolding
• Stiff brush
• Household bleach
• Rags
• Gloves and eye protection
• Sandpaper
• Paint brush (polyester for latex primer and natural-bristle for oil-based primer)
• Primer
• Roller
• Paint tray
• Mineral spirits

Instructions

1. Correct any moisture problems. Moisture may be coming from inside your home, or it may be the result of poorly performing eavestroughs and/or downspouts.

2. Remove the loose, peeling or flaking paint using a paint scraper. Be careful not to scratch, gouge or dent the surface below the paint. Remove peeling paint from a large area using a power washer.

3. Treat any mildew with a solution of three parts water to one part household bleach. Wear gloves and eye protection. Leave the solution on for 20 minutes, then rinse thoroughly with water.

4. Scrub the surface thoroughly with a stiff brush and water to remove any dirt, chalky residue or treated mildew. Rinse thoroughly with water. Allow to dry.

5. Sand all bare spots if the surface is wood. This will help the primer and paint layers to adhere.

6. Prime the surface, using an exterior primer recommended for the surface you are painting. Check the weather report prior to getting out the paintbrush or roller; do not prime if there is a chance of rain or if the temperature will be under 50 degrees Fahrenheit. Use a paintbrush for smaller areas and a roller for larger areas. Use a higher nap roller for rough surfaces. Paint larger surfaces in three foot by three foot sections. Roll paint on in a "W" shape, then roll paint into the empty areas.

7. Clean all brushes and/or rollers. Use mineral spirits if priming with an oil-based product. Store or dispose of primer according to the instructions on the can.

Tips & Warnings

• According to Mark T. Knaebe, a chemist at the Forest Products Laboratory in Madison, Wisconsin, you can perform a "Band-Aid test" to determine if you need to remove all the existing paint prior to repainting. Clean and paint a small, hidden area. Let it dry overnight, then stick a Band-Aid to the new paint and pull it off. If the Band-Aid removes all the paint down to the original surface, Knaebe recommends stripping all the paint off. Depending on the scale of the project it may be less expensive to replace the exterior surface you were thinking of repainting.

• Lead paint is toxic. If you suspect that there may be lead in the peeling paint, do not attempt to scrape, power wash or use a heat gun on it. Contact a contractor who is qualified to perform lead assessment and abatement.

• Apply paint to the primer soon after it is dried, since unpainted primer degrades after as little as two weeks. If you can't paint right away, scrub the primer and rinse thoroughly before painting.

References

• Paint Quality Institute: Paint Advice and Techniques for Your Home
• This Old House: Why Is My Paint Peeling?
• Behr: How to Repair Flaking Paint