How to Prep Exterior Wood for Painting

Before you touch a paintbrush, inspect every piece of exterior wood on your home. Look for:

• Rot: Press a screwdriver into suspect areas. Soft, spongy wood is rotted and must be replaced or filled.
• Cracks and splits: Small cracks can be filled with exterior wood filler. Large splits may require board replacement.
• Loose boards: Secure any boards that have pulled away from the structure. Re-nail or screw them tight.
• Missing caulk: Check every joint where wood meets another surface - windows, doors, corners. Old or cracked caulk must be removed and replaced.
• Insect damage: Termites and carpenter ants are common in Florida. Damaged wood must be replaced entirely.

For minor rot, use a two-part epoxy wood filler. It hardens to a paintable surface and resists moisture better than the original wood. For extensive rot, replace the entire board. Painting over rotten wood is a waste of paint and money.

Grove Street Painting includes trim and fascia restoration as part of their exterior prep process. If repairs are needed, they are identified during the estimate walkthrough and included in the fixed-price proposal.

Every piece of exterior wood must be clean before sanding or priming. Here is the proper cleaning process:

Salt-Neutral Washing

In Sarasota and the barrier islands - Siesta Key, Longboat Key, Bird Key, Casey Key - salt deposits build up on exterior surfaces. Standard pressure washing does not remove salt. You need a salt-neutralizing wash solution applied before rinsing.

Mildew Treatment

Florida humidity breeds mildew on exterior wood. A solution of bleach and water (1:3 ratio) or a commercial mildewcide kills mildew spores. Let it sit for 15 minutes, then rinse thoroughly. Painting over mildew causes the paint to peel.

Pressure Washing

Use low pressure (under 1,500 PSI) on wood surfaces. High pressure damages wood grain and forces water into the substrate. Keep the nozzle 12-18 inches from the surface and move steadily.

Drying Time

Wood must be completely dry before sanding or priming. After pressure washing, wait 48-72 hours in dry weather. Use a moisture meter to confirm the wood is below 15% moisture content. In humid Florida months, drying may take longer.

Once the wood is clean and dry, it is time to sand.

For previously painted wood:

• Scrape off all loose, peeling, or flaking paint with a paint scraper
• Sand the edges where old paint meets bare wood to create a smooth transition (no sharp paint edges)
• Sand the entire surface with 80-120 grit sandpaper to create a profile for the new paint to grip
• Wipe down with a tack cloth or damp rag to remove all dust

For bare wood:

• Sand with 80-120 grit to open the grain and create a bonding surface
• Remove all sanding dust with a tack cloth
• Apply a wood conditioner if the species is prone to blotching (cedar, redwood)

Caulking: After sanding, apply exterior-grade paintable caulk to every joint. Use silicone-acrylic caulk for flexibility and adhesion. This seals gaps where water enters and causes rot. Run a smooth bead and tool it with a wet finger for a clean line.

Priming exterior wood is not optional - especially in Florida. Primer serves three critical functions:

1. Seals the wood to prevent moisture from entering the substrate
2. Blocks stains from tannins, knots, and water marks bleeding through the finish
3. Creates adhesion between the wood surface and the topcoat

Best primers for exterior wood in Florida:

• Oil-based primer: Best adhesion and stain blocking. Ideal for bare wood, cedar, and redwood. Longer dry time but superior penetration.
• Acrylic latex primer: Flexible, mildew-resistant, and fast-drying. Good for previously painted wood in stable condition.
• Shellac-based primer: Best stain blocker for severe tannin bleed or water stains. Dries in 30 minutes.

Apply primer within 48 hours of sanding. Bare wood left exposed absorbs moisture and contaminants that compromise adhesion. One coat of primer is standard. Bare wood or stain-prone species may need two coats.

Need professional wood prep and painting? Exterior painting services in Sarasota from Grove Street Painting include complete surface preparation, premium primers, and a 10-year written workmanship warranty on all exterior work.

Call (941) 504-3552 for a free estimate.