Home Crawl space rodent control
Crawl spaces · Oxford, Mississippi
Rats in the crawl space? How to get them out
Scratching under the floor, a smell coming up through the vents, a burrow beside the foundation. Crawl spaces are where Norway rats live. Here is how they get in, what they damage, and how the space gets sealed.
- Norway rats live low
- Vents and pipe gaps
- Ducts and vapor barrier
- Sealed with metal
Smell coming through the vents? Read about duct damage.
Start here
How do you get rats out of a crawl space?
Find how they get in, seal it with metal, then trap. Rats under the house are usually Norway rats, which burrow along foundations and forage 100 to 500 feet from the nest, according to University of California IPM. They get in through broken crawl space vent screens, a loose access door, gaps where pipes and wires pass through the foundation, and burrows under the footing. University of California guidance is to seal any opening larger than 1/4 inch, because young rats can squeeze through 1/2 inch. Cover vents with 1/4 inch hardware cloth, close pipe gaps with metal and mortar, fit the access door tight, then set rat-size snap traps along the foundation walls inside. Check torn ducts and vapor barrier, because rats damage both.
Signs
Signs of rats in your crawl space
You rarely see the rats. You find what they leave.
Noise under the floor
Scratching, gnawing and scurrying under the floor at night, often under the kitchen or near plumbing.
Burrows by the foundation
Smooth-edged holes along the foundation, under slabs, stoops or AC pads, often with fresh dirt pushed out.
Large blunt droppings
About 3/4 inch with blunt ends, near the access door, along walls and on ductwork.
Smell through the vents
A musty or rotten smell from floor registers can mean rats in the ducts or a dead rat in the crawl space.
Damaged vapor barrier
Torn, bunched or shredded plastic on the crawl space floor, often with nesting in it.
Chewed lines
Gnawed flex duct, insulation, wiring or plastic water lines under the house.
How they get in
How rats get into a crawl space
Most crawl spaces have more than one way in. All of them get sealed.
| Entry point | What to look for | The lasting fix |
|---|---|---|
| Crawl space vents | Missing, rusted or bent screens | 1/4 inch hardware cloth, fastened tight |
| Access door | Gaps at the edges, rotted frame, no latch | A tight-fitting door with a latch and sweep |
| Pipe and wire penetrations | Gaps around plumbing, gas, AC lines, cable | Copper mesh packed in, then mortar or sealant |
| Foundation cracks | Cracks or missing mortar in block or brick | Mortar repair |
| Burrows under the footing | Fresh holes along the foundation | Fill, and an L-shaped hardware cloth barrier buried at the base |
| Dryer and HVAC openings | Gaps where vents or line sets pass through | Metal collars and sealant |
University of California IPM advises sealing all openings larger than 1/4 inch. Norway rats are strong diggers and swimmers and can come up through broken drains, so any damaged sewer cleanout or drain under the house is worth a look too.
How we seal it
How a crawl space gets sealed and cleared
Seal, trap, confirm. The crawl space is just a tighter place to do it.
Inspect
We walk the outside foundation and go into the crawl space to find every vent, gap, burrow and damaged area.
Seal
Hardware cloth on vents, metal and mortar at pipe gaps, a tight access door, and burrows closed off.
Trap
Rat-size snap traps along the foundation walls and runways inside, checked on a schedule.
Confirm
A full week with no catches and no fresh droppings before the job is called done.
The same metal-first standard as every job. More on exclusion and sealing.
Ducts and vapor barrier
Ductwork, vapor barrier and insulation damage
What rats break under the house costs more than the rats.
Many Oxford homes on crawl spaces have flexible ductwork running under the floor. Rats tear into it for nesting, which leaks conditioned air into the crawl space and can pull droppings, dust and smell into the house through the registers.
The CDC advises calling a professional for rodent problems in ventilation systems rather than running the system to clear it. Torn ducts usually need sections replaced and sealed after the rats are gone.
A torn vapor barrier lets ground moisture up into the crawl space, which can lead to damp insulation and wood. Shredded barrier should be patched or replaced once the space is clear.
- Flex duct torn or crushed
- Duct insulation pulled loose
- Smell from floor registers
- Vapor barrier torn or bunched
- Floor insulation hanging down
- Damp or musty air under the house
Smell from the vents could also be a dead rat. See our guide to dead rodent smell.
Under the house
Hearing rats under the floor?
Call or send the form. We seal every way into the crawl space, trap what is inside, and show you photos of the damage. The price is in writing before any work starts.
DIY or pro?
Can you handle a crawl space rat problem yourself?
Some fixes are easy. Finding all of them is the job.
Some of it, yes. Replacing a vent screen or fitting a better access door is a weekend job. Packing a pipe gap with copper mesh and sealant is too.
The hard parts are finding every entry point, working in a tight, dirty space, and dealing with burrows under the footing and damaged ducts. That is where most people call for help.
- DIY: replace a vent screen with 1/4 inch hardware cloth
- DIY: fit a tight access door with a latch
- DIY: seal pipe gaps with copper mesh and sealant
- Pro: burrows under the footing
- Pro: torn ductwork and smell from registers
- Pro: rats still active after two weeks
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Straight answers
Crawl space rat questions
What kind of rats live in crawl spaces?
Usually Norway rats. They are heavy, burrowing rats that live low: along foundations, under slabs and in crawl spaces. Roof rats live high, in attics. Their droppings are about 3/4 inch with blunt ends.
How do rats get under my house?
Through broken vent screens, a loose access door, gaps around pipes and wires, foundation cracks and burrows dug under the footing. University of California IPM advises sealing any opening larger than 1/4 inch.
Can rats in the crawl space get into my house?
Yes. They follow pipes and wires up through gaps under sinks, behind the dishwasher and around the water heater. Sealing those interior gaps is part of the job.
Why does my house smell when the heat or AC runs?
Rats may have torn into ductwork under the house, or one may have died in or near the ducts. The CDC advises a professional for rodent problems in ventilation systems.
Should I put poison in the crawl space?
We do not recommend it. Poisoned rats often die in the crawl space or walls, which causes a smell that can last weeks. Snap traps let you see and remove every catch.
Do I need to replace my vapor barrier?
Only if rats have torn it. Patches work for small tears; heavily shredded barrier should be replaced after the rats are gone.
How long does crawl space rodent control take?
Typically one visit to inspect and seal, then trap checks until a full week passes with no catches and no fresh droppings. Two to three weeks is common.
Keep reading
Related rodent help for Oxford homes
From the blog: questions people ask
Sources
Last reviewed October 2026 by the Rodent Control Oxford team. Biology and control standards follow Mississippi State University Extension and the CDC. Price ranges are labeled benchmarks; your price comes in writing after we inspect.
Oxford & Lafayette County
Hearing it again tonight?
One call gets your inspection scheduled. Tell us what you heard and where. We seal first, trap second, and the six things in writing come standard.
Serving Oxford 38655, University 38677, Taylor 38673, Abbeville 38601, Paris 38949 and the rest of Lafayette County, Mississippi.
Rodent Control Oxford. Independent, rodent-only, local.