A thorough scrubbing is a must before painting any exterior surface. It removes the dirt and broken-down paint residues that keep fresh coats from adhering and gets rid of mildew that grows on paint in all but the most arid climates. Most contractors clean with pressure washers, but in the hands of someone unfamiliar with the equipment, these can gouge wood, shatter glass, and drive water behind siding and trim. Using a hose, a pump sprayer, and a scrub brush is slower but safer, and just as effective.
Use a wire brush and a wide-blade putty knife to remove small areas of defective paint. Scrub under the laps of clapboard siding as well as on downspouts and gutters. For speedier work on metal, a wire brush attachment on an electric drill will remove rust and paint with less effort. For more extensive paint removal, invest in a sharp pull scraper -- a tool with a replaceable blade that's capable of stripping old paint all the way down to bare wood with a single scrape. Hold the scraper so the blade is perpendicular to the wood, apply moderate to firm pressure, and drag it along the surface. Keep the blade flat against the wood so it doesn't gouge the surface.
The time needed to complete an exterior paint job varies depending on the size of the home, the condition of your home’s exterior, the weather conditions and type of paint used on the job. An average project lasts 3-4 days, while a complex project may take a week or more. Additional time may be needed to fix loose or damaged siding or add primer to areas without coverage. Your painter will provide a timeline that explains how long the project will last and will schedule the job to avoid inclement weather.