Carpenter ant damage in wood framing
moderate 1–2 h
Tools: flashlight, awl or screwdriver, moisture meter (optional), vacuum, tape · Materials: wood hardener and epoxy filler for a small soft spot, caulk for entry points
Steps
- Find the frass: the fine sawdust piles with insect parts in them sit below the entry hole, and that hole marks the gallery — put tape on the wall there so you can find it at night.
- Tap along the sill plate, window headers and door frames with a screwdriver handle; hollow-sounding wood or a probe that sinks in tells you how far the galleries run.
- Measure the moisture of the wood if you can: carpenter ants nest in wood over about 20 % moisture, so a leak, a wet sill or a bad roof edge is usually next to the damage.
- Fix the water first — a dripping gutter, a leaking window, a downspout at the wall — because dry wood is what makes the nest move out.
- For a soft spot smaller than your hand in non-structural trim, cut out the damaged wood, treat with hardener, and fill with epoxy; paint and caulk every gap the ants used.
- Keep firewood and mulch away from the wall and prune branches that touch the roof — those are the ants' bridges.
Stop and call a pro if
- the soft wood is a joist, beam, sill plate or header, or the probe sinks more than 1 cm (⅜ inch) into framing
- you see winged ants indoors — the colony is mature and inside the structure
- the damage is spread along more than one wall
What a pro does that you can't
A pest-control technician finds the parent colony and every satellite nest, treats with baits and a non-repellent product that the workers carry back, and a carpenter sisters or replaces framing that has lost its strength.
DIY cost: $15–40 in filler, hardener and caulk