Intro
Proper surface preparation is essential to a successful paint job, so don't skimp on time or elbow grease. Depending on the condition of the siding and trim, you may spend much more time preparing for painting than actually applying the paint.
The ideal surface for a good appearance is smooth yet slightly roughed up so the paint can adhere. In cases of severe damage or heavy paint buildup, you need the ultimate approach: Scrape and sand down to bare wood. A more moderate approach is usually enough: Sand the paint smooth and apply primer. If the existing surface is in good condition, you can get by with washing, spot-sanding, and priming.
Rotted areas can be hardened and holes filled, but if the area is large, you might want to simply replace the boards.
Prestart Checklist
Time
You can wash 300 square feet in 1 hour or less. Scraping down to bare wood may take weeks.
Tools
Pressure washer, paint scrapers, power paint remover, sanding blocks, power sander, heat gun, paintbrush, wire brush, steel wool, putty knife, abrasive pads, caulking gun, utility knife, ladders and/or scaffolding
Skills
Patient attention to detail
Prep
Protect plantings and lawn with drop cloths.
Materials
Sandpaper, liquid or paste paint remover, caulk, wood filler, wood hardener, epoxy filler, glazing putty