Carpenter ants on a home inspection: what it means

What does it mean if a home inspection finds carpenter ants?

Carpenter ants on a home inspection report usually point to wet wood somewhere in the house. The ants don't eat wood. They tunnel into it, and NC State Extension says they prefer wood that is already damp. Book a licensed pest control company to find the nest before your deadline, then ask the seller to cover the treatment, the leak and any damaged wood.

Key takeaways

• The pest company's written wood destroying insect (WDI) report, not the home inspector's note, is what you negotiate from.
• Ants seen foraging indoors don't prove a nest indoors. Sawdust-like debris, rustling in a wall, or winged ants inside are stronger signs.
• Homeowners insurance usually won't pay for carpenter ant damage, so ask for the money while the seller still owns the house.

Can carpenter ants ruin a house?

Carpenter ants can damage a house, but usually less than termites do. NC State Extension adds a warning: "a carpenter ant problem that is ignored or goes unnoticed can lead to significant damage to wood."

How much damage depends on the colony. The Illinois Department of Public Health says large colonies "can be destructive; however, are more of a nuisance than a threat to structural integrity." The National Pest Management Association warns on its PestWorld that the tunneling "can compromise the structural soundness of the wood over time."

Indoor nests often start in moist wood. Illinois lists leaking chimney flashing, skylights, windowsills, doorframes, porch supports and flat roofs. NC State says the colony is fairly slow-growing, taking up to six years to mature. Which view fits this house, and how far the damage runs, is a question for the pest company's inspection.

If the pest company finds damaged joists, beams or posts, treat it as a structural finding. Get a structural engineer's inspection before you set your number. Foundation and structure findings shows how this line compares to others on the report.

How do you confirm an active infestation?

A licensed pest control company confirms an active infestation. Your home inspector saw a sign; the pest company finds out whether there is a nest, where it is, and what wood is damaged. NC State calls a thorough search time-consuming and tedious, and suggests a pest control company. PestWorld adds that "the sooner carpenter ants are treated, the less serious the damage is likely to be."

Signs worth pointing out to the technician, from NC State:

• Sawdust and frass that looks like pencil shavings, often mixed with insect parts.
• Winged ants indoors, which point to a nest in or under the house.
• Rustling sounds from a wall or void where a mature colony is nesting.
• Slit-like openings in wood where the ants push out debris.

Ants foraging near a sink are not proof on their own. NC State says finding them inside "does not necessarily mean that they are nesting indoors."

Ask for the findings in writing on a WDI report. The standard NPMA-33 form lists carpenter ants among the insects it covers, next to termites and carpenter bees. It is a visual inspection of accessible areas, not a guarantee against hidden or future damage.

Ask the technician to name the insect too. A report can also flag carpenter bee damage or powder post beetles, which are treated differently. How to get repair estimates during the inspection period covers booking the visit fast.

How much does a carpenter ant inspection and treatment cost?

A carpenter ant inspection can cost $75 to $150 on its own. Defender Termite & Pest Management, a Sacramento-area pest company, says some companies charge that separate fee, while others fold it into the job. Ask which way a company prices before you book. The treatment price climbs when the nest is deep in the framing or the wood needs repair.

If your report has other lines too, Kept prices every line of an inspection report for $79, usually under 4 hours.

The leak that drew the ants is not in any of these rows. Illinois public health guidance says to correct moisture problems such as leaky plumbing and faulty seals around windows and doors. Defender says treating without fixing the moisture source makes re-infestation likely. NC State goes further: if the damage is severe, repairing or replacing the wood "may be more important than any treatment." Price the leak with a roofer's or plumber's written bid, and see wood rot on an inspection report for the wet wood itself.

What should I ask the seller for?

Ask the seller for treatment, wood repair and the leak fix, as a completed repair or a credit. Each line names the scope, the trade and a figure.

Say the pest company finds a satellite nest in a wet window frame. Using Defender's Sacramento-area figures, treatment plus wood repair runs $1,500 to $3,500 or more. The company's separate inspection fee, if it charges one, is your own cost, so leave it off the seller's line. The request line reads:

Carpenter ant treatment by a licensed pest control company; repair of damaged window framing by a licensed contractor per written bid: $1,500 to $3,500+. Leak repair at the window: written bid to follow.

Swap in the written bids as soon as you have them. If the seller does the work, ask for the pest company's written report of what it treated and repaired, and a copy of any treatment warranty.

What to ask for after a home inspection covers which lines to include, and the buyer repair request letter template gives you the wording.

What if the seller says no?

If the seller says no, you still have moves:

• Ask for a credit at the top of your bid range instead of the repair.
• Walk away if the damage reaches the framing and the bids come in above what the house is worth to you. See when to walk away after a home inspection.
• Budget for it yourself if the bids fit and the house is otherwise right.

Your contract sets the exact dates and terms, so confirm them with your agent or attorney.

Does homeowners insurance cover carpenter ant damage?

Homeowners insurance usually won't cover carpenter ant damage. Progressive says insurers treat it as general home maintenance, and "even if you didn't know you had an infestation, insurance companies typically won't cover damage resulting from the ants." Once you close, the repair is yours.

How do you get rid of carpenter ants for good?

You get rid of carpenter ants for good by treating the nests and fixing the moisture. Illinois says the reliable fix is treating the nest directly, which may mean drilling into walls or frames. The main nest is usually outdoors, and killing only an indoor satellite nest can let ants from it come back. NC State says complete eradication can take one to two weeks, especially with a large colony, and baits can take 7 to 10 days before activity drops.

If carpenter ants are one line of a long report, upload your inspection report to Kept and spend your remaining days on the pest company's visit and the leak bid.

Sources

• NC State Extension, Biology and Control of Carpenter Ants
• Illinois Department of Public Health, Carpenter Ants
• PestWorld, Carpenter Ants 101
• This Old House, How Much Does an Ant Exterminator Cost?
• Defender Termite & Pest Management, Carpenter Ant Extermination Cost
• NPMA-33 Wood Destroying Insect Inspection Report (Ohio Department of Agriculture copy)
• Progressive, Does Home Insurance Cover Termite Damage?