Property risk
Pest and wildlife entry
An undisturbed building with no human activity is exactly what a nesting animal is looking for.
What happens
Mice require an opening of about six millimetres. Rats, squirrels and birds need only slightly more, and all of them will enlarge an existing gap.
Entry concentrates at predictable points: utility penetrations, dryer vents, soffit and roof junctions, foundation cracks, garage door seals, and around basement windows.
Fall drives the highest pressure as animals seek overwintering sites, and a quiet building with no vibration or human scent is preferable to an occupied one.
Damage compounds over a long vacancy. Rodents chew wiring and insulation, contaminate stored materials, and a nest in a wall cavity can go undiscovered for an entire season.
Alberta has no established Norway rat population thanks to the provincial rat control programme, which removes one problem — but mice, squirrels, birds and wasps are all common.
Why vacancy makes this worse
Occupancy itself is a deterrent. Its absence, combined with long discovery intervals, allows a small entry point to become an established population.
What a visit can observe
- Droppings, particularly along walls, in cupboards and in the mechanical room
- Gnaw marks on materials, packaging or wiring
- Nesting material in insulation, storage or appliances
- Scratching or movement sounds in walls or ceilings
- Urine odour
- Chewed or disturbed insulation
- Wasp or hornet nests at eaves and in outbuildings
- New openings at soffits, vents or foundation level
Reducing the risk
- Seal entry points before an extended vacancy, particularly utility penetrations and vent terminations.
- Remove all food, including pantry items, before departure.
- Have interior and mechanical areas checked for evidence at each visit.
- Keep vegetation trimmed back from the building.
- Address evidence promptly — established populations are much harder to remove.
Related questions
How long can a house sit empty?
Physically, a house can sit empty indefinitely if it is maintained — heated, water managed, monitored and looked after. The limiting factors are not structural, they are practical: insurance, deterioration and the accumulation of unnoticed problems.
The insurance constraint is usually the binding one. Many policies begin restricting coverage after roughly thirty days of vacancy, though the threshold and the consequences vary. Beyond that point some owners need a specialised vacant-property policy, which is a different product with different terms and typically a higher premium.
The deterioration constraint is gradual and cumulative. Traps dry within weeks. Pests establish over a season. Moisture problems compound. Systems that sit idle behave unpredictably when restarted. None of these are dramatic on their own; together over a year they produce a property that needs significant work.
The real answer is that a house can sit empty for a long time safely, provided somebody is attending to it. It is unattended vacancy rather than vacancy itself that causes the damage.
What actually happens to a house when it sits empty?
Less dramatically than people imagine in the first month, and more than they expect over a year.
Within weeks: plumbing traps dry out and sewer gas enters the building, producing the characteristic stale smell of an empty house. Dust settles undisturbed. Air becomes stale without the ventilation that ordinary occupancy provides.
Within months: pests find their way in, particularly through the fall. Small leaks that would have been noticed immediately run continuously. Moisture accumulates in unventilated spaces. Landscaping deteriorates visibly, and the property starts announcing its own vacancy.
Over a year or more: systems left idle can seize or fail on restart. Moisture problems develop into mould. Rodent populations establish. Exterior maintenance issues compound — a small roof problem becomes a leak, a drainage issue becomes a basement problem.
Almost all of this is prevented by ordinary attention: heat maintained, water managed, fixtures run, the property visited, and problems caught while they are still small.
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