When painting your home’s exterior walls, preparation is critical to a successful, lasting job. In many cases, simply washing the surface to be painted is not enough. Paint that has begun to fail usually must be completely removed to ensure that the new coat will adhere properly. While this is a significant job, the reward is a great-looking, durable finish.

1) Begin by hosing down the siding, and then scrubbing it with a stiff-bristle brush mounted on a broomstick-type pole. Clean the area with a solution of water and trisodium phosphate (TSP) or a nonphosphate substitute, following label directions. Because this solution is caustic, do not use it on bare wood, and wear rubber gloves and safety goggles.
2) Scrape loose paint, and, if necessary, use a power sander to remove large areas of paint or to smooth any roughly scraped surfaces. When using a sander, work in 3-foot sections at a time. Move horizontally across the top of a board, in a wave-like pattern across the middle, and then along the underside of the lip.
3) Fill any holes or deep gouges, using a putty knife to apply vinyl exterior spackling compound. (Use a matching wood-toned filler if you intend to apply a semitransparent stain.) Allow the spackling compound to dry.
4) Use a sanding block or a palm sander with 100-grit sandpaper to sand each patch until it is smooth. Finally, sweep away residual dust and scrapings.