Fall Rodent Control for Commercial Buildings in Toronto: What to Do Before Mice and Rats Move In

Fall is when rodent problems in Toronto commercial buildings usually start. As nights get colder in October and November, house mice and Norway rats move from outdoor burrows and landscaping into buildings that offer warmth, food and shelter. The best time to act is before that happens: seal gaps around doors, pipes and utility penetrations, clean up food sources and harbourage, and put monitoring in place so any activity shows up early.

Once rodents are established inside walls, ceilings and equipment, removing them takes longer and costs more. A fall program is mostly about prevention.

Rodents move indoors as it cools

House mice and Norway rats are the two rodents most commercial buildings in Toronto deal with. Both stay active all winter. Neither hibernates. When outdoor food gets scarce and temperatures drop, they look for a warm place close to a food supply.

Commercial buildings offer exactly that. Restaurants, grocery stores, food processors and warehouses are obvious targets, but offices, retail stores and residential towers with commercial ground floors get them too. Break rooms, garbage rooms, loading docks and mechanical rooms are common entry and nesting areas.

Construction also pushes rodents around. When a nearby site is excavated or an old building is demolished, rodents living there move to the next suitable building. In a city with as much active construction as Toronto, that is worth keeping in mind if activity suddenly appears.

Common entry points

Mice can fit through very small gaps. A commonly cited guideline is that a mouse can get through an opening about the width of a pencil, and a rat through a gap not much bigger than a quarter. On a commercial building, the usual entry points are:

• gaps under overhead doors and dock doors, especially worn or damaged seals
• doors propped open during deliveries
• utility penetrations where pipes, conduits and cables enter the building
• gaps around HVAC units, vents and exhaust fans
• cracks in foundations and where different building materials meet
• floor drains and damaged sewer connections, a common route for rats
• shared walls in strip malls and mixed-use buildings

A fall inspection walks the outside of the building at ground level, the roof line and the inside of the envelope from the basement or ground floor, looking for these gaps and for signs of activity like droppings, gnaw marks and rub marks along walls.

Exclusion: sealing the building

Exclusion means physically closing the gaps. Common materials include:

• door sweeps and brush seals on exterior doors
• replacement seals on dock doors and dock levellers
• copper or stainless steel mesh packed into gaps, sealed over with a durable sealant
• sheet metal or hardware cloth over larger openings and vents
• concrete or mortar for foundation cracks

Expanding foam alone is not enough. Rodents chew through it. It needs to be combined with a metal barrier.

Our commercial rodent exclusion guide goes into materials and methods in more detail.

Sanitation and harbourage

Exclusion works much better when there is less to attract rodents in the first place. Before winter:

• keep garbage in containers with tight lids and empty them often
• clean under and behind kitchen equipment, shelving and appliances
• store food and food-contact supplies off the floor and away from walls
• break down and remove cardboard promptly from loading docks and storage rooms
• trim landscaping away from the building and clear debris piles along exterior walls
• repair leaking pipes and drains that provide water

Ontario and Toronto requirements

Several rules apply to rodent control in Toronto commercial buildings.

Food premises. Ontario's Food Premises regulation (O. Reg. 493/17) under the Health Protection and Promotion Act requires food premises to be protected against the entry of pests and kept free of conditions that lead to the harbouring or breeding of pests. Toronto Public Health inspects food premises through its DineSafe program, and evidence of rodents can lead to infractions, closure orders or both.

Property standards. Toronto Municipal Code Chapter 629, Property Standards, requires buildings to be kept free of rodents, vermin and insects. This applies to commercial and residential properties.

Pesticide licensing. In Ontario, pest control using pesticides on structures is regulated under the Pesticides Act and O. Reg. 63/09. Applicators need the appropriate exterminator licence, and operators need the right licence for the business.

Rodenticide rules. Health Canada's Pest Management Regulatory Agency (PMRA) restricts how rodenticides are used. The more potent products are limited to certified applicators, and baits placed where children, pets or non-target animals could reach them must be in tamper-resistant bait stations.

A pest control provider should know all of these and keep records that show it. Inspectors and auditors will ask for them. See what a proper service report should include in our post on pest control service reports.

Monitoring through the winter

After exclusion and cleanup, monitoring tells you whether the program is working. A typical commercial setup includes:

• tamper-resistant bait stations around the exterior perimeter
• traps or monitoring devices inside, especially in food storage, kitchens, garbage rooms and along walls
• a map showing where every device is placed
• regular service visits with documented findings and corrective actions

Visit frequency depends on the type of building. Food businesses and warehouses usually need more frequent service than offices.

Frequently asked questions

Why do mice come inside in the fall?

Mice and rats move indoors in fall because outdoor temperatures drop and food becomes harder to find. Commercial buildings offer warmth, shelter and food, so rodents look for gaps around doors, pipes and foundations to get in. Neither species hibernates, so they stay active indoors all winter.

How do you keep rodents out of a commercial building?

Seal entry points with durable materials such as metal mesh, door sweeps, dock seals and sealant, reduce food and harbourage through good sanitation, and set up monitoring with bait stations and traps. Expanding foam alone does not work because rodents chew through it.

Are restaurants in Toronto required to have pest control?

Ontario's Food Premises regulation requires food premises to be protected against the entry of pests and kept free of conditions that lead to pests. Toronto Public Health inspects restaurants through DineSafe, and evidence of rodents can lead to infractions or closure. Most restaurants keep a regular pest control program with documented visits to meet these requirements.

Do pest control companies in Ontario need a licence?

Yes. Structural pest control using pesticides in Ontario is regulated under the Pesticides Act and O. Reg. 63/09. Applicators need the appropriate exterminator licence, and businesses need an operator licence.

Get your building ready before winter

If you manage a commercial building or run a food business in Toronto, send us the property details through our quote form. We will follow up in writing with an inspection plan and a free quote.