With so many exterior paints and coatings to choose from, and so many different types of surfaces to be painted or coated, there's a great deal to know about exterior painting and coating. Still, most homeowners ask the same few questions about house painting and coating.
Below is a sampling of the most common questions and some abbreviated answers, provided by the Rohm and Haas Paint Quality Institute. For more detailed advice, you should speak to a knowledgeable Painting Contractor.
Question: How are surfaces prepared for painting?
Answer: Any surface intend to be painted should be sound and clean. When painting wood, loose, flaking or peeling paint is removed by sanding, scraping or wire brushing. The surface is then cleaned with a power washer; or scrubed with soap and water and followed with a thorough rinsing.
Question: When is a primer applied?
Answer: Generally speaking, a primer should be applied to any surface that has never been painted before. When repainting, a primer is needed when the surface is uneven in porosity, or when the surface has been stripped of paint or is worn down to the substrate (bare wood is a good example).
Question: Is it better off to apply a water-based latex paint or an oil-based paint?
Answer: That depends. Top quality latex paints and coatings generally have excellent adhesion to most surfaces and exhibit superior resistance to bleaching and fading when compared to oil-based materials. But if the surface is heavily chalked, and there isn't the opportunity to remove all the chalk, the surface should be cleaned, primered, and then painted.
Question: Can water-based paint go over oil-based paint?
Answer: Yes. But the surface will need to sanded and an oil-based primer applied before you applying an acrylic latex paint. Oil based paint is primarily applied on wood surfaces.
Question: Are there any guidelines to follow when selecting the degree of glossiness for the new paint?
Answer: Yes, paints with higher glossiness -- oil-based paint -- are more stain resistant and easier to clean than are flat finishes, so they are good choices for areas like exterior doors, windows and trim. They also are more mildew resistant than flat paints. But higher gloss paints emphasize surface imperfections; as a result, flat paints are preferable for surfaces like dented or irregular siding.
Question: Is it worth spending the extra money for a top quality paint?
Answer: Absolutely. According to the Paint Quality Institute, the highest grade of paint within a manufacturer's line of coatings always offers the best value, because it will look better longer and provide years of extra service. The products may cost a few dollars more per gallon, but it can extend the life of the paint job to 10 years or more compared with three or four years of service for ordinary Paint.
Question: What are the best weather conditions for exterior Painting?
Answer: Ideally, a mild day with the temperature between 60°F and 96°F, with little or no wind. Also, it is best to avoid painting directly in the hot sun, since the surface of your house can be 10 to 20° hotter than the air temperature.