Rats: Hidden Movement in Your Walls and Ceilings
Rats are rarely seen in the daytime, which is why many households only notice them after the signs have built up for weeks. They are active mostly at night, and they move along the same routes between their nest, their food and their water. Once a rat has found a reliable food source and a sheltered route into the building, it will keep using both.
In Singapore, the species most often found in homes are the roof rat, which climbs and nests high in ceilings and roof spaces, and the brown rat, which burrows and lives at ground level, often near drains and sewers. Both can enter buildings through small gaps, and both are capable of causing damage and spreading disease.
This guide explains how to recognise the signs of rats, where they get in and nest, the health risks they carry, why DIY traps and poisons often fail, and what a professional rodent control programme involves.
Signs of Rats at Home
Rats leave evidence long before you see one. Checking for these signs regularly helps you catch an infestation early.
Droppings:
- Roof rats: Small, dark, spindle-shaped, about 1 to 1.5 cm long
- Brown rats: Larger, blunt-ended, about 1.5 to 2 cm long
- Where to look: Along walls, under sinks, in cabinets, in kitchens, and around food and water sources
Gnaw Marks and Damage:
- Chewed wires, cables and pipe insulation, which can create a fire risk
- Gnawed food packaging, cardboard, plastic containers and wooden edges
- Holes in walls, cabinets, ceilings and skirting boards
Rub Marks and Runways:
- Dark greasy smudges along walls, pipes and beams where rats brush against them repeatedly
- Well-worn paths along skirting boards, rafters and cable runs
Noise, Smell and Nests:
- Scratching, scurrying or gnawing sounds in ceilings or walls, especially at night
- A strong ammonia-like smell in heavy infestations, from urine
- Shredded material, insulation or fabric in hidden spaces, used as nesting material
Where Rats Get In and Nest
Rats can squeeze through openings far smaller than most people expect. A gap about the width of a coin can be enough for a young rat, and an adult can fit through an opening roughly the size of a golf ball. They climb pipes and cables, chew through soft materials, and use drains as routes into buildings.
Common Entry Points:
- Gaps around pipes and cables: Where they enter walls, ceilings and kitchens
- Drains and floor traps: Particularly in older buildings and ground-floor units
- Gaps under doors and at door frames: Especially where weather strips are worn
- Vents, grilles and air-conditioning openings: Where mesh or covers are damaged
- Roof spaces and ceiling voids: Reached by climbing trees, pipes or neighbouring structures
- Gaps around windows and service doors: Often left open for ventilation
Common Nesting Spots:
- Ceiling voids and roof spaces (roof rats)
- Wall cavities and behind appliances
- Under floors, in ducts, and in cluttered storage areas
- Garden sheds, bins and dense vegetation close to the building
Why Rats Are a Health Risk
Rats carry bacteria and viruses that can spread to people through contact with their urine, droppings, bites or contaminated food and water. Leptospirosis and salmonella are among the diseases associated with rats. Rat urine can contaminate surfaces, and dust from droppings can become airborne when disturbed, which is a particular risk during cleaning.
Rats also damage property. Chewed electrical wiring can cause short circuits and fires, and gnawed pipes can lead to leaks and water damage. They contaminate stored food, and they spread through drains and sewers into neighbouring units in multi-unit buildings.
Why DIY Traps and Poisons Often Fail
Household traps and poison baits can catch a rat, but they rarely solve the problem. Rats are wary of new objects, so a trap placed in the wrong spot or set without checking the routes often goes untouched. Poison can cause rats to die inside walls or ceilings, where the smell becomes a long-term problem and carcasses are difficult to retrieve. Poison also carries risks to children, pets and non-target wildlife if placed carelessly.
The bigger issue is entry. If the gaps that let rats in are not sealed, new rats will keep arriving, and a single successful trap does not change that.
- Inspecting the building for entry points, nesting areas, runways and food sources
- Identifying the species (roof rat or brown rat) so the approach matches their behaviour
- Placing bait stations and traps in the right locations and monitoring them safely
- Sealing entry points with appropriate materials to stop reinfestation
- Advising on sanitation, food storage and waste management
- Follow-up visits to confirm the infestation has been cleared
What You Can Do Between Visits
- Store food in sealed, rat-proof containers and never leave pet food out overnight
- Keep bins closed and take rubbish out regularly
- Clear clutter, cardboard boxes and vegetation close to the building
- Seal visible gaps around pipes, cables and vents using durable materials such as metal mesh or cement
- Check door sweeps and weather strips, and replace worn ones
- Keep drain covers in place and report any damage
- Wear gloves and a mask when cleaning areas where droppings are present
When to Call a Professional
- You find droppings, gnaw marks or rub marks in more than one room
- You hear scratching or movement in the ceiling or walls at night
- Wiring, pipes or stored food have been damaged
- Traps have been set but the signs keep returning
- Your building has a known rat problem, such as in a drain or shared service area
- Children, elderly people or anyone with a weakened immune system live in the home
Seeing Signs of Rats at Home?
Speak to GreenCare about a professional inspection and a clear rodent control plan for your property.
Thorough inspection, sealed entry points, and follow-up for your home.
