Preparing Siding

Starting at the eaves and soffits, wash the surface with water only. Use a pressure washer equipped with a fan nozzle and adjust the pressure for cleaning wood surfaces. Do not hold the tip too close to the wood. A power washer can poke holes in wood and break windows.

Working from the top of the wall to the bottom, direct the water downward. Spraying head-on can damage the siding, and aiming the spray upward can drive water behind the siding and lift it from the wall. Turn the water off to release pressure before disconnecting the hoses.

Using a 5-in-1 tool or scraper held almost flat against the surface, scrape away loose paint down to the bare wood. To avoid gouging the surface, work parallel to the grain of the wood as much as possible. On carved millwork, use contoured scrapers available at your home center or paint store.

Using a 5-in-1 tool or stiff scraper, widen cracks to just under 1/4 inch. This will remove debris in the crack and create a recess for patching compound. Remove loose paint with 80-grit sandpaper and take up any dust with a brush and water-dampened rag.

Apply a thin layer of exterior patching compound to all scraped and cracked areas, feathering the compound to create a level surface. Allow the compound to dry thoroughly. If the compound shrinks, sand it lightly and apply another thin layer.

Sand patched areas with 100-grit sandpaper to make the compound level with the existing paint. This leveling process will help hide the repair when you apply the primer. Remove dust with a wide brush or damp cloth.

Apply an exterior stain-blocking primer on all repaired areas and all bare wood. This prevents wood tannins from discoloring the paint. On cedar, redwood, and mahogany, use an oil-base primer and apply it in dry weather at the recommended spread rate. Finish-coat the surface within a week.

Mask, cover, or otherwise protect plants, surfaces, or objects that could be damaged by the cleaning solution. Dampen grass, plants, and other vegetation with water. Wet the mildewed area with water using a pump sprayer, a garden hose, or a pressure washer.

Mix a cleaning solution of three parts water and one part household bleach in a pump sprayer and apply it liberally. Scrub the mildewed area with a stiff brush, reapplying the solution to keep the area wet for 20 minutes.

Using a pressure washer or hard spray from a garden hose, rinse the area thoroughly with water. Take up any protective coverings from adjacent surfaces and rinse vegetation with a light spray from the hose. Let the surface dry thoroughly.