How to Tell If Rats Are Under Your House
You can tell rats are under your house when you find holes in the soil against the foundation, large droppings near vents or the crawl door, or gnawing at ground level. Night-time gnawing or scrabbling beneath the floor is often the first hint, but the physical evidence confirms it.
Check for these, starting outside:
- Holes beside the foundation, under steps, porches and decks, often with loose soil in front.
- Large, blunt droppings on the ground by vents, the crawl door or the slab edge.
- Gnawed vent screens or crawl doors at ground level.
- Rats seen near the house. University of Nebraska-Lincoln Extension treats rats seen at night, or in daytime, alongside fresh droppings and gnawing as a sign of a large population.
If the holes you have found are out in the yard rather than at the house, our guide to identifying rat burrows explains how to read them.
Why Norway Rats Live Under Homes
Norway rats live under homes because they are burrowers that prefer to stay low and close to food. UC IPM states that when Norway rats invade buildings, “they usually dwell in the basement and ground floor areas.” The space under a floor gives them soil to dig, cover and a short trip to the kitchen.
Roof rats are the opposite: agile climbers that UC IPM places above ground, in attics, walls and false ceilings. So the location of the noise is itself a clue to the species, and to the treatment.
Once settled, they stay put. UC IPM notes that when food and nest are close together, rats keep their travel as short as they can. A colony under a house is not passing through.
It also grows. University of Nebraska-Lincoln Extension reports litters of 6 to 12 young, with the average female producing 4 to 6 litters a year and young reaching breeding age at about 3 months.
Burrows Along the Foundation
Burrows along the foundation are how Norway rats get beneath a house without using a vent or door. They dig down beside the footing and tunnel under it, or they follow the soil into the gap under a slab, porch or stoop.
University of Nebraska-Lincoln Extension records Norway rats burrowing under buildings and beneath concrete slabs. UC IPM adds that burrows are found “along building foundations, beneath rubbish or woodpiles.”
Once under a structure, rats look for a way up. In a National Environmental Health Association training session, the presenter explained that rats burrowing under a building are searching for a weak point, “either in a plumbing penetration or a crack in the foundation or an expansion joint.” That is why a burrow at the foundation is never just a yard problem. It is a route toward the inside of the house.
Rats in Crawl Spaces
Rats in crawl spaces are one version of a rats-under-the-house problem, not the only one. A Norway rat colony can be under a slab edge, a back porch, a deck or a shed and never enter a crawl space at all.
Where a house does have a crawl space, it gives rats the most room. They come in through damaged vent screens, under loose access doors or up through burrows dug inside the foundation wall, then nest in the soil out of sight.
House age does not decide this. U.S. Census Bureau estimates show 29.0% of Chesapeake’s housing units were built in 2000 or later, and a newer home’s stoop, patio slab or deck gives rats the same soil to dig under as an older one. Wherever a house sits on a crawl space, we inspect it.
What happens under the floor once rats are found, from vent screening to cleanup, is covered on our crawl space rodent control page.
Damage Under the Floor
Damage under the floor from rats comes from gnawing and digging, and it reaches pipes, wiring, framing and the soil that supports slabs and steps.
Nebraska Extension’s list of rat damage includes:
- Gnawing electrical wires and water pipes, both in structures and below ground
- Chewing openings through doors, window sills, walls, ceilings and floors
- Undermining building foundations and slabs by burrowing
The undermining is the least obvious, because it happens in the soil beneath slabs, stoops and steps where nobody looks. Pipe and wire damage under a floor is similar: it is usually found during an inspection, not noticed from inside the house.
How Rats Are Removed
Rats under a house are removed by trapping and by treating the burrows and nesting sites, with bait stations placed outside. University of Nebraska-Lincoln Extension calls trapping “the preferred method to try first in homes, garages, and other small structures where there may be only a few rats present.”
Placement does most of the work. Traps go along the runs between the burrow and the food, where the rats already travel, rather than in open ground they avoid.
Our rat control service combines trapping, burrow and nesting-site treatment and exterior bait station placement, and we come back afterward to check the traps and stations and change the treatment if rats are still active. Every catch is removed and disposed of.
How Entry Points Are Sealed
Entry points are sealed after the rats are removed, never before, and with hardened materials that rats cannot chew through. eXtension’s warning is blunt: “Be sure all the rats are out of the burrow. If you seal them in, you risk a terrible odor as they decompose.”
Size the repair to the animal. University of Nebraska-Lincoln Extension says rats can get through or under any opening higher or wider than 1/2 inch, so a gap that looks too small to matter usually is not.
For a rat problem under a house, the sealing list usually covers:
- Burrow entrances along the foundation, closed once they are confirmed empty
- Gaps under porches, stoops and steps where rats dig in
- Foundation vents, rescreened with rat-proof mesh
- Pipe and cable penetrations through the foundation
Our rodent proofing and exclusion work seals the outside of the house, and covers carpentry and foundation repair where the structure itself has given way.