Learn the 7 most common signs of a rat infestation in BC homes, from droppings and chew marks to nesting sites, and what to do once you spot them.
The most common signs that rats have entered your home are dark, capsule-shaped droppings near food sources or along walls, scratching or gnawing sounds at night, and greasy smear marks along baseboards where rats repeatedly travel. Gnaw marks on wiring should be treated as urgent, since they’re a fire hazard.
1. Rat Droppings
Rat droppings are the most common first sign of an infestation. Norway rat droppings are dark brown, capsule-shaped, and about 15–20mm long — roughly the size of a large raisin. Fresh droppings are shiny and soft; older droppings are dry and crumbly. Concentrations of droppings near food sources, along walls, or in cupboards indicate active rat activity in that area.
2. Scratching and Gnawing Sounds
Rats are most active at night. Scratching sounds in walls, ceilings, or under floors after dark indicate rats travelling through your home’s structure. Gnawing sounds — particularly near pipes or in the attic — are a serious warning sign, as rats chew through wiring and insulation causing fire and moisture damage.
3. Grease Marks Along Walls
Rats travel the same routes repeatedly, always keeping body contact with walls and surfaces. This leaves dark grease smears along skirting boards, walls, and around pipe entry points where the oil and dirt from their fur transfers to surfaces.
4. Gnaw Marks
Look for fresh gnaw marks on food packaging, structural timber, PVC pipes, and electrical cables. Rat teeth never stop growing, so rats gnaw constantly. Gnaw marks on wiring are a fire hazard and should be treated as an emergency.
5. Nesting Material
Rats build nests from shredded paper, fabric, insulation, and plant material. Nests are typically found in undisturbed areas — behind appliances, inside wall cavities, in the attic, or under debris in the garage.
6. Footprints and Tail Drag Marks
In dusty areas like lofts and crawl spaces, you may see rat footprints (four toes on front feet, five on back) and tail drag marks in dust or soil.
7. Live or Dead Rats
Seeing a rat during daylight hours indicates a large, well-established infestation. Rats are naturally nocturnal; daytime sightings occur when competition for food and space within the colony forces weaker animals out during the day.
How to Prevent a Rat Infestation
A rat infestation isn’t just structural damage and gnawed wires — droppings and urine can carry bacteria and viruses, including hantavirus, which spreads through dust contaminated with rodent waste. Avoid vacuuming or dry-sweeping droppings, since this can send harmful particles into the air; dampen the area with a diluted bleach solution first, then clean up while wearing gloves.
Preventing a rat infestation is far easier than treating an established one. Seal any gaps larger than a coin around your foundation, vents, and utility lines using steel wool or wire mesh, since rats can squeeze through openings as small as a quarter. Store food in sealed metal or glass containers, keep garbage bins tightly closed, and clear woodpiles, dense vegetation, and clutter away from your home’s exterior walls, since these give rats both shelter and easy access. For more detailed guidance, HealthLink BC’s guide on getting rid of rodents is a helpful resource. If you’re already seeing signs of a rat infestation, don’t wait, since early treatment is faster, cheaper, and safer than dealing with an established colony.
What to Do Next
If you’ve spotted any of these signs, act immediately — rat populations double roughly every two months. Read our guide on how to get rid of rats in Surrey BC, explore professional rat control in Surrey, or learn about effective rodent control across BC. Contact Top Line Pest Control for same-day service.