Mouse control

Mice announce themselves in October. The nights turn, the house is warm, and suddenly there is scratching behind the kitchen kickboard and droppings in the cutlery drawer. The instinct is to buy bait. The thing that actually ends it is sealing the building, and everything else is support.

Know how small the gap is. Health Canada puts it plainly: mice can squeeze through cracks as small as a dime, and rats through a quarter-sized hole (Health Canada, rats and mice). That changes where you look. The gap around a gas line entry, the corner of a garage door seal, the space where a dryer vent passes through a rim joist, the chase behind a kitchen cabinet. It is rarely an obvious hole.

Step one: inspection and evidence. A technician looks for droppings, urine staining under ultraviolet light, greasy rub marks along walls and joists, gnawing on packaging and wiring, and nesting material. The signs Health Canada lists include scampering and scratching in walls at night, evidence of gnawing, and damaged food packages. The distribution of droppings tells you which rooms are active and roughly how many animals are involved.

Step two: exclusion. This is the part that works. Gaps are stuffed with steel wool or copper mesh before being caulked or plastered, which is exactly the method Health Canada describes. Larger openings get sheet metal or hardware cloth. Vents get fine mesh screening. Weather stripping and door sweeps go on. Anything filled with expanding foam alone is a temporary measure, because mice chew through foam without difficulty.

Step three: trapping rather than baiting. Snap traps and electronic traps generally kill rats and mice instantly, and Health Canada states that baits or poisons should not be used as the only method of control. There is a practical reason as well as an ethical one: a poisoned mouse dies somewhere you cannot reach, usually a wall cavity, and you then live with the smell for two or three weeks. Traps are set in numbers, along walls with the trigger toward the wall, and checked daily.

Step four: sanitation. Food in sealed containers, crumbs dealt with, pet food not left down overnight, garbage secured, clutter reduced. Health Canada also advises raising woodpiles about 30 centimetres off the ground and cutting back vegetation against the house.

Step five: safe clean-up. Wear rubber gloves and a dust mask, and never sweep or vacuum dry droppings, because that aerosolises them. Dampen the area with a disinfectant first, wipe up, and bag the waste. This is Health Canada's advice and it is the step homeowners most often get wrong.

How long it takes. Inspection is an hour. Exclusion of a typical house is half a day to a day and a half depending on the foundation and how many entry points there are. Trapping runs over one to three weeks with a follow-up visit or two. A whole programme, from first call to confident quiet, is usually three to six weeks.

What it costs in Ottawa in 2026. Indicative ranges, matching this site's price guide. Mouse control with basic exclusion generally runs $200 to $500, covering the inspection, the trapping or stations, a follow-up and sealing of the obvious gaps. Thorough exclusion of a whole building, which is the part that actually ends the problem, is usually quoted separately and costs more, driven by the perimeter, the foundation type and how much of it can be reached. Clean-up and insulation replacement in a badly affected attic is a separate job again. The single best question to ask of any quote is how much of it is exclusion.

What makes an Ottawa house different. The cold does the scheduling. Calls spike sharply from late September through November as mice move indoors ahead of the first hard frost, and again in late winter. Older housing stock in the core, Hintonburg, Vanier, Sandy Hill and the post-war inner suburbs, often has stone or block foundations with mortar joints, and those are very hard to seal completely. Attached garages, close to universal in the suburbs from Nepean through Barrhaven and Kanata, are the most common route into a modern house, usually under the garage door seal and then through the service penetrations into the living space. There is also a legal dimension for renters: Ottawa's Property Standards By-law requires a dwelling to be kept reasonably free of pests and from conditions that may encourage infestations, and requires openings such as vents, pipe penetrations, cracks and floor drains to be screened or sealed to prevent pests entering (City of Ottawa, Property Standards By-law 2013-416, section 13).

Who should do the work, and the licence that matters. Anyone may set traps in their own home. Where a licence applies is pesticide use: in Ontario you need a pesticide exterminator licence to apply pesticides commercially on any property that you or your employer do not own or farm, the relevant class here is structural extermination, and the business itself needs a pesticide operator licence. The Ministry of the Environment, Conservation and Parks regulates this, with conditions for trainees and technicians working under supervision set out in O. Reg. 63/09 (Ontario, pesticide licences and permits). Ask to see the licence.

What to ask before you hire. How much of your quote is exclusion rather than product. Where specifically are they getting in, and can you show me. Are you using traps or rodenticide, and if rodenticide, how do you manage the risk of a dead mouse in a wall, and how are the stations secured against children and pets. Are you sealing the garage. How many follow-up visits are included. What is the warranty and what voids it. Is clean-up included.