How to Paint Exterior Wood Trim | Prep, Paint, and Finish Right

For the full breakdown, see our best Exterior Paint For Wood Trim guide.

One wrong move—like painting over damp wood or skipping primer—can ruin the finish within months. The work is mostly prep, and the steps are the same whether you’re freshening a front door frame or redoing the whole house. Here’s the exact order that gets you a lasting result.

Step 1: Inspect and Repair the Trim

Before you wash or scrape, look closely at every board. Poke soft spots with a screwdriver; if the wood gives way easily, the rot runs deeper than the surface. Replace any boards that are rotted, cracked through, or missing sections. Painting over damaged wood is a temporary fix—moisture will push the paint off within a season. For minor holes and cracks, use an exterior wood filler rated for outdoor use.

Step 2: Clean, Scrape, and Sand

Exterior trim collects dirt, mildew, and chalking (the powdery residue that forms on old paint). Wash the whole surface with a mild detergent and water, or a bleach-and-water mix for mildew. Rinse thoroughly and let the trim dry for at least 24 hours, or longer if it’s been raining.

Scrape every patch of loose or peeling paint with a putty knife until the remaining paint is firmly bonded. Sand the edges of that remaining paint so the transition is smooth—start with 80-grit on rough areas, move to 100-grit, then finish with 120- or 220-grit. If the trim has a glossy sheen, sand the whole surface to dull it; paint won’t grip gloss well.

Step 3: Caulk and Prime

Run a bead of paintable exterior latex caulk along every seam between the trim and the siding, and around window and door frames. Fill nail holes with wood filler or spackle. Let the caulk and filler cure fully—the paint won’t adhere over damp sealant.

An exterior primer is non-negotiable on any bare wood, repaired spot, or surface where the old paint is worn thin. Sherwin-Williams and Benjamin Moore both recommend a latex exterior primer as the base layer. Primer seals the wood, prevents tannin bleed, and gives the topcoat something to lock into. Let it dry per the label directions.

Step 4: Apply Paint in Thin, Smooth Coats

Use a high-quality exterior trim paint in satin or semigloss; these sheens hold up to weather and are easier to clean than flat finishes. Pour the paint into a small bucket, dip the brush about one-third of the way into the paint, and tap off the excess against the side. Overloading the brush causes drips.

Start at the top of the trim and work down. Paint with the grain of the wood using long, smooth strokes. Finish each section by laying off: one light, even stroke that smooths out the brush marks. Let the first coat dry completely—check the can for recoat time, usually four to six hours—then apply a second coat the same way.