Getting rid of rats in your garage requires a combination of trapping, sealing entry points, and removing what attracted them in the first place. Rats can squeeze through a gap the size of a quarter, so even a small opening under your garage door is an open invitation. The good news is that most garage infestations can be handled yourself with the right approach and a bit of patience.
Confirm You’re Dealing With Rats
Before you start setting traps, make sure you’re identifying the problem correctly. The most common garage invader is the Norway rat, a stocky ground-dwelling rodent weighing roughly half a pound. Norway rats dig burrows along foundations and slab edges, then use the garage as a place to forage and nest. Look for burrow entrances about 2.75 inches in diameter near the exterior foundation, typically with a fan of excavated dirt around them.
Inside the garage, the clearest evidence is droppings. Norway rat droppings are capsule-shaped with blunt ends, about 18 to 20 mm long. If you’re finding droppings that are only 3 to 8 mm with pointed ends, you have mice instead, which changes your trap selection. Also look for dark grease marks along walls near the floor. Rats have oily fur that leaves visible smudges on surfaces they travel along repeatedly. Nests, when you find them, are loosely constructed balls of shredded material roughly the size of a softball.
Find and Seal Every Entry Point
Trapping without sealing entry points is a losing battle. New rats will simply replace the ones you remove. Start with a careful inspection of your garage’s perimeter, both inside and out. You’re looking for any opening larger than a quarter inch. A useful test for the garage door itself: if you can see daylight under or around the door when it’s closed, the gap is large enough for a rat to get through.
Common entry points include the bottom and side gaps around the garage door, where utility pipes or wires pass through walls, foundation cracks, and vents without screens. Standard rubber garage door seals are easy for rats to chew through, so once damaged, they become permanent access points. Replace worn seals with rodent-resistant versions or reinforce them.
For sealing gaps, use 19-gauge hardware cloth with half-inch by half-inch mesh openings. This is the standard recommended by building science guidelines for rat exclusion. Stuff it into openings around pipes, behind vents, and over any gaps in the wall. For larger structural gaps, galvanized sheet metal (24-gauge or heavier) works as a barrier rats can’t gnaw through. Expanding foam alone won’t stop a rat. They chew right through it. If you use foam for insulation purposes, back it with hardware cloth first.
Set Traps the Right Way
Snap traps remain the most reliable method for a garage. They’re inexpensive, reusable, and you can confirm each kill rather than wondering if a poisoned rat crawled into your wall to die. The key to success is quantity, placement, and a trick called prebaiting.
Start by placing unset traps baited with a pea-sized amount of chunky peanut butter in areas where you’ve found droppings, grease marks, or nesting material. Leave them unset for a couple of days until the bait has been taken multiple times. Rats are cautious around new objects in their environment, and this conditioning step gets them comfortable with the traps before you arm them. Skip this step and you’ll catch far fewer rats.
Placement matters more than bait choice. Rats run along walls and edges rather than crossing open space, so every trap should sit flush against a wall or structural edge, forming a “T” shape with the baited trigger end touching the wall. Set traps in pairs, side by side or end to end with triggers facing opposite directions. This catches rats traveling in either direction. Space pairs every few feet along walls where you’ve seen activity.
Set many more traps than you think you need. Rats breed fast, and there are never just one or two. A dozen traps for a single-car garage is reasonable. Check traps daily, rebait as needed, and keep trapping until you go several consecutive days with no catches.
Why Poison Is Risky in a Garage
Rodenticides are widely available, but they carry serious risks that make them a poor first choice for a garage, especially if you have pets, children, or wildlife nearby. All forms of rat poison are highly toxic. The most common types cause internal bleeding that kills over three to five days, brain swelling leading to tremors and seizures, or kidney failure from concentrated vitamin D3. A dog or cat that eats a poisoned rat, or finds the bait itself, faces the same dangers.
There’s also a practical problem: poisoned rats often die in inaccessible spots inside walls, above ceilings, or under stored items, creating a lingering smell that can last weeks. If you do use bait stations, place them only inside tamper-resistant boxes that pets and children can’t open. Record exactly how much bait you placed and where, check stations regularly to confirm bait hasn’t been dragged elsewhere, and keep the original packaging so you can identify the active ingredient in an emergency.
Skip the Ultrasonic Repellents
Ultrasonic pest repellers are marketed heavily, but they don’t work in real-world conditions. While laboratory studies have shown that high-powered ultrasonic generators can disrupt rodent behavior, those devices are several grades above anything sold to consumers. The commercial plug-in units can’t replicate the complex sound patterns needed to have any effect. Controlled studies on consumer-grade devices are extremely limited, often lack proper comparison groups, and have never reliably demonstrated that the sound itself caused any reduction in pest activity. Save your money for traps and exclusion materials.
Remove What Attracts Them
Rats enter your garage because it offers food, water, shelter, or all three. Eliminating these attractants makes your trapping more effective and prevents reinfestation after you’ve cleared the current population.
- Food sources: Pet food, birdseed, grass seed, and garden supplies stored in bags or cardboard boxes are easy meals. Transfer everything to sealed plastic or metal containers with tight lids. Even grease residue on a grill stored in the garage can draw rats in.
- Water sources: Fix any leaking pipes, hose connections, or condensation drips. Remove standing water from buckets, drip trays, or floor drains that hold moisture.
- Clutter and shelter: Rats nest in undisturbed piles of cardboard, fabric, insulation, and stored belongings. Clear items off the floor and away from walls. Store things on shelving rather than in stacked boxes on the ground. The less hiding space available, the less hospitable your garage becomes.
Clean Up Safely
Rat droppings and urine can carry diseases, including hantavirus, which spreads when contaminated dust becomes airborne. The single most important rule during cleanup: never sweep or vacuum droppings. Sweeping launches virus-carrying particles into the air you’re breathing.
Before you touch anything, open all garage doors and windows and leave the space to ventilate for at least 30 minutes. When you return, put on rubber or plastic gloves. Spray droppings, urine stains, and nesting material thoroughly with a bleach solution (1.5 cups of household bleach per gallon of water, mixed fresh) or an EPA-registered disinfectant. Let it soak for five minutes. Then wipe everything up with paper towels and dispose of them in a covered trash bag.
For dead rats or nests, spray the area with disinfectant first, let it soak, then place the remains in a sealed plastic bag. Consider applying insect repellent to your clothing and hands before handling dead rodents, since fleas are common on rats and can carry their own diseases. After cleanup, mop or sponge all hard surfaces with disinfectant. Wash your gloved hands with soap before removing the gloves, then wash your bare hands again.
If you’re dealing with a heavy infestation, with large accumulations of droppings or extensive nesting, step up your protective gear. Wear disposable coveralls, rubber boots or shoe covers, protective goggles, and a respirator with a HEPA filter. Standard dust masks are not sufficient for heavy contamination.
How Long the Process Takes
A typical garage infestation takes one to three weeks to resolve with consistent effort. The first two to three days are for prebaiting traps and letting rats get comfortable with them. Once you arm the traps, most catches happen within the first week. Continue trapping until you’ve had at least three to five days with no new catches, no fresh droppings, and no signs of new gnawing or grease marks.
If you’re still catching rats after two to three weeks of active trapping, or if you find new burrow entrances appearing outside despite your sealing efforts, the colony may be larger than a DIY approach can handle. Persistent infestations, rats inside wall cavities, or signs of structural damage to the garage are all situations where a licensed pest control professional has access to more effective tools and can assess the full scope of the problem.