How to Patch Holes in Wood Siding

Water is the greatest enemy of your home's exterior, and a hole in your wood siding is an open invitation for rot, pests, and structural damage. Whether caused by woodpeckers, errant nails, or simple weathering, these gaps act as sponges that pull moisture directly into the wall cavity. Patching them isn't just about aesthetics; it is a critical maintenance task that preserves the integrity of your exterior envelope. Done well, a patch should be invisible and watertight, standing up to the thermal expansion and contraction that happens naturally with wood. Avoid using standard interior spackle or cheap fillers that will crack after the first season. Using the right materials and following the grain—literally—ensures your repair lasts as long as the wood surrounding it.

  1. Excavate All Loose Wood. Use a stiff wire brush to remove loose paint, splinters, and any decayed wood fibers from inside the hole. Ensure the cavity is dry and free of debris to allow the filler to bond properly.
  2. Kill Rot Before It Spreads. Brush a liberal coat of borate-based wood preservative into the hole and onto the surrounding area. This kills existing fungi and prevents future rot from taking hold behind your patch.
  3. Pack the Void Fully. Press exterior-grade wood filler or two-part wood epoxy into the hole using a putty knife. Overfill the hole slightly to account for shrinkage as the material cures.
  4. Sand Flush With Siding. Once the filler is cured, use a sanding block with 80-grit sandpaper to bring the patch flush with the surrounding siding. Follow up with 120-grit paper to smooth the transition for painting.
  5. Seal Before Final Paint. Apply a high-quality exterior primer specifically formulated for wood to the patch and the immediate area. This creates a uniform surface for the topcoat to stick to.
  6. Blend Color Into Siding. Apply exterior-grade paint that matches your siding color, using a small brush to feather the edges into the existing siding. Use two thin coats rather than one heavy one for the best match.