Mouse and Rat Control in Markham

Mouse and rat control in Markham starts with a free inspection, then trapping, locked bait stations only where they make sense, and sealing every gap the rodents used to get in. A mouse job here typically runs $200 to $500 and a rat job $300 to $600 and up, quoted on the spot before any work starts. Call or send the form and a mice exterminator can usually be booked for the same day. In a Markham subdivision the animal in the wall is far more often a house mouse than a rat; rats turn up mostly where there is food outside and digging nearby. For everything else we treat in the city, see pest control in Markham, and for the background on each animal, our York-wide guides to mouse control and rat control.

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Mouse or rat: how to tell in a Markham house

Start with the droppings. A mouse leaves dark pellets about the size of a grain of rice, pointed at the ends, scattered along the route it runs. A rat leaves capsules well over a centimetre long, blunt at both ends, often in a pile.

Then think about where you found them. Mice climb. You hear them in the ceiling over the kitchen, behind the fridge, in the attic of a two-storey. Rats are heavier and stay low: under the deck, along the foundation, in the garage, in a basement near the floor drain. A rat inside the house nearly always means a burrow outside it.

Size decides the sealing. Health Canada notes that mice get through a crack as small as a dime and rats through a hole the size of a quarter (Health Canada, rats and mice). Different animal, different gaps, different materials.

How mice get into Markham's subdivision homes

Markham was built in waves, and every wave has its own weak spots. We check the same list on every house, just in a different order depending on when it went up.

1980s and 1990s two-storeys in Milliken, Middlefield and Raymerville. Brick veneer with weep vents along the bottom course, original garage door seals, and dryer vent and hose bib openings that have had decades to loosen. The hole where the air conditioner line set enters the wall is a regular culprit.

2000s builds in Berczy, Wismer and Greensborough. Tighter walls, but the garage is still the soft spot: the bottom corners of the overhead door and the man door into the house. The cold cellar under the front porch, where the porch slab meets the foundation wall, is another one we check every time.

Freehold townhouse rows in Cornell and Cathedraltown. Mice ignore property lines. If one unit in a row has them and the neighbours do nothing, the shared attic space and the party wall keep feeding the problem back. We seal your envelope and tell you plainly when the source is next door.

Older homes near Main Street Unionville and Markham Village. Older foundations, mortar joints that have moved, crawlspaces under additions, and years of service lines punched through the wall. These take the most sealing time, which is why they sit higher in the price range.

The Rouge side of the city

Markham's east side borders a lot of open land. Rouge National Urban Park makes up over 16% of the city's land area and sits just east of Cornell Centre, running out toward the hamlet of Locust Hill (City of Markham, Cornell Rouge gateway study). Field mice live in that ground all summer.

For a house near that edge, two things follow. Sealing matters more than trapping, because nobody is going to empty a national park of mice. And some of what you catch in a shed or garage may be deer mice, which the Public Health Agency of Canada lists among the hantavirus carriers. Clean old droppings wet, never with a broom or a shop vac.

Where rats show up in Markham

Rats in Markham follow food and disturbed ground. We find them behind restaurant plazas where bins sit open overnight, on lots next to an excavation, and in backyards with an open compost heap, seed under a bird feeder, or a shed sitting on bare earth.

The City's own property-standards guidance names compost specifically: a composter has to be kept so it will not attract "rodents such as mice or rats" (City of Markham, property standards). Garbage timing matters too. Markham picks up clear-bag garbage every other week and the green bin every week (City of Markham, clear bag garbage), so a household holds up to two weeks of garbage between pickups. Keep it in a hard can with a tight lid, not loose bags on the garage floor. York Region Public Health gives the same advice: rodent-proof containers with tight-fitting lids (York Region, preventing rats and rodents).

A rat in a Markham basement lives in the yard. Find the burrow and the food, and the indoor problem stops.

What the treatment involves

1. Free inspection, inside and out. Droppings, runs, gnaw marks, nest sites, and every opening at the foundation, garage, roofline and utility entries. This is also where mouse versus rat gets settled.
2. Trapping. Snap traps in the runs and behind appliances, placed out of reach of kids and pets. Traps clear the mice already inside quickly and do not leave one dying in a wall.
3. Locked stations only where they fit. Any rodenticide goes into a tamper-resistant station. Health Canada requires a tamper-proof station anywhere children and pets can reach, and commercial-class products can only be applied by a certified professional. Every product is Health Canada-registered and used to label.
4. Exclusion. Steel mesh and sealant for mouse gaps; hardware cloth, sheet metal or mortar for rat openings, since a rat chews through foam. For rats, active burrows are treated and then collapsed.
5. Follow-up. We come back to clear traps and check that the seals held. If activity carries on within two months, one re-treatment is free.

Doing it yourself versus calling

One mouse in the garage in October, no droppings in the kitchen, nothing moving in the ceiling: set three snap traps with a dab of peanut butter flush against the wall, look hard at the garage door corners, and you may be finished. That is a reasonable DIY job.

Call when droppings turn up in more than one room, when you hear movement overhead at night, when the traps keep filling, or when you see anything that looks like a rat or a burrow. Rats are a poor DIY project on a subdivision lot. The burrow work needs heavier materials, and loose bait in a yard puts dogs and the street's cats at risk. Our guide to whether you need an exterminator draws the line in more detail.

Renting, condos and the City's rules

If you rent in Markham, the landlord deals with rodents. Section 20 of Ontario's Residential Tenancies Act puts repair and maintenance of a rental on the landlord, and York Region Public Health points tenants to that same duty. Put the problem in writing, date it, keep a copy, and give access for the visit. In a condo, York Region Public Health notes that the board has a legal duty to maintain the property, so report mice coming through common walls to management, not just your own unit.

Owners carry a duty as well. Markham's Property Standards By-law 2017-26 requires a home, inside and outside, to be kept free of rodents and insects at all times. If a neighbouring property is feeding the problem, the City's By-law Enforcement and Licensing Department takes complaints at 905-479-7782 or customerservice@markham.ca. This is York Region, not Toronto, so Toronto's programs and phone lines do not apply here.

Common questions

Reviewed October 2026.

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