How deep do they dig?
Often 2 to 6 feet, with tunnels that can total 20 to 50 feet and more than one entrance. Depth depends on the soil. Under a stoop, that is enough to matter.
Groundhogs under structures How much damage can a groundhog burrow do?
Enough to settle a step or a slab, if the tunnel runs under it. The fix is an empty den and a buried barrier, not a can of something dangerous.
Key facts
- A burrow system often totals 20 to 50 feet and sits 2 to 6 feet underground.
- Systems include nesting, food, and hibernation chambers, plus more than one entrance.
- Dens under decks, sheds, and slabs can undermine footings and cause settling.
- Relocating live-trapped groundhogs is illegal in many states.
- Few poisons are legal for groundhogs around homes. A carcass under the floor becomes an odor and a biohazard.
- Carbon monoxide fumigation can seep into a crawl space. It is not a homeowner method.
- After exclusion, bury heavy galvanized hardware cloth 12 to 18 inches, with the bottom bent outward.
How big is the burrow?
Groundhogs are powerful diggers. A working burrow is not a single hole. It can run tens of feet, drop several feet, and include rooms for sleeping, food, and winter. You may see one entrance and miss the back door in the hostas.
They like the edge where a field meets a yard, and they like a roof they did not have to build. A deck, a shed, a crawl space, or a gap along a footer is that roof. They reuse and enlarge the same system year after year.
Why are poison and gas a bad idea here?
Few toxicants are registered for groundhogs, especially at a house. Poison under a structure can kill pets and scavengers that eat the carcass. The other problem is location. An animal that dies in the burrow rots under your floor. Odor, insects, and a mess you cannot reach come with that.
Fumigating a burrow with carbon monoxide or carbon dioxide is restricted, often limited to agricultural or licensed use, and dangerous when tunnels connect to a crawl space. Carbon monoxide has no smell. Burrows are also branched, so the gas often never reaches a lethal level everywhere. You get the risk without a reliable result.
What about trapping?
Live trapping is regulated state by state and may require a permit. It can remove one animal. It is awkward under a low deck, and moving the animal somewhere else is illegal in many places because of disease and because relocated animals often die. Lethal traps, where they are even allowed, still have to follow local rules. A trap does not fill the hole. Skunks and opossums will borrow an empty groundhog burrow.
What does a lasting repair look like?
Confirm the burrow is empty. Backfill entrances with compacted soil or gravel. Then stop the next digger. Heavy-gauge galvanized hardware cloth or welded wire goes around the foundation or under the deck skirt, buried at least 12 to 18 inches, with the bottom bent outward in an L so tunneling under it is frustrating.
The garden damage is annoying. The footing is the expensive part. Look at where the tunnel goes before anyone talks about concrete.
What changes by region?
Northeast Indiana
Fort Wayne yards that back up to a field, a ditch, or a weedy fence see groundhogs every summer. Indiana sets the rules for trapping and for moving wildlife. We do not fill an active burrow, and we do not gas a den that may connect to a crawl space.
Central Ohio (coming soon)
Ohio also regulates nuisance wildlife, and relocating animals is limited. Poison and fumigants under a house are a poor idea in either state.
Common questions
Is a groundhog the same as a woodchuck?
Yes. Same animal. Woodchuck, groundhog, and, in some families, whistle-pig.
Can I pour gravel in the hole?
Not while it is occupied. You either waste a Saturday or trap the animal under the house. Empty first, then backfill, then bury a wire apron.
The smell changed. Is it still a groundhog?
Maybe not. Skunks and opossums use old groundhog holes. The digger and the current resident are not always the same animal. Say so if the smell showed up later.