Whether your house has a basement, a crawl space or a slab, its lowest edge meets the ground along its full length. That edge is full of potential openings, and few people look at it. Rodents know it well, since a foundation gap is a straight path from soil to shelter.
Common entries below the house.
- Cracks in the foundation or mortar.
- Loose or rusted vent screens.
- Gaps where plumbing, wiring or gas piping enters.
- A crawl space door that does not close tightly.
- Open window wells and damaged basement windows.
- Gaps beneath exterior doors.
Mice need a hole about the width of a pencil. Rats need about half an inch. Both can enlarge a gap by chewing soft materials.
Signs below the first floor.
Look for droppings along walls and pipes, grease marks on foundation walls, shredded insulation and nests behind stored boxes. A musty or sharp smell near the furnace or water heater can also point to activity. Pet reactions, such as staring at a wall, are another clue.
| Area. | What to check. | Why. |
|---|---|---|
| Crawl door. | Seal, latch and gaps. | A common entry. |
| Vents. | Screens, rust, loose edges. | Light screens tear easily. |
| Utility entries. | Gaps around pipes and wires. | Short routes into the house. |
| Stored goods. | Cardboard, fabric, paper. | Ideal nest material. |
Moisture and clutter.
A damp lower level can soften wood and attract insects, and clutter gives animals cover. Fix leaks, run a dehumidifier if needed and keep stored items off the floor in lidded tubs. These steps do not remove rodents, but they make a space less welcoming.
What a technician does.
The technician inspects the foundation line, the crawl door and vents, and the utility entries. Traps follow the evidence, then sealing closes the openings with metal and heavy mesh. If the space is fouled, attic and crawl space cleanup removes waste and soiled insulation.
Describe your house to us: basement, crawl space or slab, and how you reach it. If you have a mid-century modern house on a slab with little below it, the inspection puts more weight on the roof and walls. Tell us what applies.
Would you rather speak with a person? The number below rings the same desk at noon or at 3 a.m.
Ring (888) 686-4821A seasonal check.
Each autumn, open the crawl door, look at the vents and walk the foundation outside. A few minutes with a flashlight can save a larger job later.
Wiring, ducts and insulation below the floor.
Rodents below a house often chew the coatings on wires, the foil on ducts and the insulation under the floor. Sagging insulation, taped sections that look shredded and cold drafts in rooms above are clues. Do not handle damaged wiring, and call an electrician if a circuit trips or a light flickers.
We note and photograph what we find so the right trade can scope the repair, and the damage repair page explains how that step is priced on its own.
Questions to answer before the visit.
Where is the crawl door, and does it open fully? Is there standing water or damp soil? Is there a vapor barrier or insulation under the floor? Is the space used for storage? The answers help the technician bring the right gear and plan how long the work will take.
If you have a basement with a sump or a floor drain, say so. Those can be routes too, and a cover or a screen may be part of the plan. A little detail on the phone saves a second trip.
Cleanup safety steps from public health agencies
Pitched at householders, the list below keeps contaminated dust out of the air while you wait for an appointment.
- Dust kicks up the moment dry waste is brushed, so put the soaking step before everything else.
- Do not enter a sealed outbuilding cold. Ventilate it, then give it around thirty minutes.
- Protect your hands throughout, then scrub them clean at the end.
- Dampen every stain and pellet with disinfectant, then allow about five minutes before lifting them away.
- Choose a sealed bag over an open bin for waste, and use gloves or a tool on a carcass.
- Not well a few weeks later? A clinician is the one to ask, so describe the rodent contact to them.
Public guidelines this page relies on
Rather than ask you to trust a paraphrase, we link the full pages that the guidance came from.
- CDC: cleaning up after rodents: Air it, wet it, bag it: the household routine in the CDC's words.
- CDC: hantavirus prevention: The seal-up guidance behind the sealing and housekeeping suggestions in this guide.