In Ontario and BC, the headline structural pest isn't the termite, it's the carpenter ant. They don't eat wood; they excavate smooth galleries in it and throw the shavings out as frass (fine sawdust piles). Health Canada's own guidance makes the point that matters for buyers: carpenter ants indoors prefer moist, decaying wood, they're a moisture finding with legs.
$300 to $800 carpenter-ant treatment (complex $1,000+); the moisture source is the real costAddress soonStructureInterior
The ten second check
What else is typical in a house this age?
You are reading the carpenter ants, rodents & household pests page. Type the year the house was built and I will tell you what else tends to be true at that age, what it costs, and what to ask. One number, ten seconds.
Free. No account. Educational and impartial, not a home inspection.
Why it matters
The ants are treatable for a few hundred dollars. The wet wood they moved into is the real finding, a plumbing leak, a leaky deck ledger, a roof drip. Treating the ants without fixing the moisture is renting a solution. Rodents matter for a different reason: they chew wiring insulation (a fire risk worth an electrical cross-check) and contaminate attic insulation.
How to spot it
Frass piles below baseboards, window frames, or deck posts; large black ants indoors in cold months (a colony inside the structure, not summer foragers); smooth, clean galleries in any exposed damaged wood (vs. the mud tubes of termites). For rodents: droppings along basement walls and garage edges, gnawed wires, chewed soffit vents.
What it costs
Ontario carpenter-ant treatment runs $300 to $800 (complex, multi-visit jobs $1,000+); general ant control in Toronto ~$225 to $425. Rodent exclusion and cleanup $300 to $2,000. Structural repair depends on what the moisture did.
What to do
Address soon, and ask the better question: not "any pests?" but "any carpenter ants, and where was the moisture?"
Education and triage, not a home inspection. Casaroo flags frass, droppings, and damage from your photos and points at the moisture question. A licensed pest professional confirms and treats.
Common questions
If the seller already treated for ants, is it handled?
Treatment kills the colony, it does not fix the wet wood the colony moved into. Ask what the moisture source was and whether it was repaired, because the treatment at $300 to $800 is the cheap part and the water damage behind it may not be.
Are carpenter ants a structural problem?
They can be, because they excavate galleries in wood rather than eating it. Whether the damage matters structurally depends on where it is and how long it has been going, which is a question for a contractor or a structural engineer once the moisture source is identified.
Do I need to disclose or worry about this at resale?
Active infestation and unrepaired water damage are the sort of thing buyers ask about and inspectors find. A documented treatment plus a repaired moisture source is a much better story to hold than a treatment alone.
Should mice or rats change how I look at the electrical?
It is worth a mention to your electrician. Rodents chew wiring insulation, which is a fire risk, and they contaminate attic insulation, so a rodent finding is a reason to look harder rather than a standalone problem.
Last reviewed 2026-07-10.
This guide is general education, not a home inspection and not advice for your specific property. Always
consult the appropriate licensed professional, and get a licensed home inspection before you remove conditions
or buy. Cost ranges are 2026 estimates that vary by region, size, and access; confirm specifics with a
qualified professional.