Rat BurrowsAround the House

A Norway rat burrow has a main opening 2 to 4 inches across, edges worn smooth from use and freshly dug dirt spread in a fan shape around it. That description comes from eXtension’s Pests in the Home resource. Nebraska Extension gives a slightly narrower 2 to 3 inches, so “roughly 2 to 4 inches” is a fair rule.

What you see on the surface is only part of it. Underneath, eXtension says the tunnels and rooms are “no further than 18” deep,” with a main entrance and one or two other entrances “that may be less obvious or concealed.” UC IPM’s Pest Notes illustrate a burrow with an “escape hole lightly covered with dirt.”

That hidden exit matters. If you find one hole, assume there is another you have not spotted, and expect more than one rat: eXtension notes a burrow often holds several, along with nest chambers and stored food.

Norway rats dig burrows where soil is easy to work and food, water and cover are close. eXtension notes they prefer sandy soil and often burrow under bushes or dense plants, beneath a porch, deck, shed or barn.

UC IPM’s list of rat signs around a home adds more specific spots:

• Under a compost pile or beneath garbage cans
• Under a garden tool shed or doghouse
• Along building foundations
• Beneath rubbish or woodpiles, and around gardens

A clean yard does not rule them out. UC Cooperative Extension wildlife advisor Niamh Quinn has described rats burrowing and nesting under steps and near AC units even where trash is fully contained, because shelter matters to them as much as food.

U.S. Census Bureau estimates show 67.4% of Chesapeake’s housing units are single-family detached houses, so most homes here sit in a yard of their own. In a yard, the spots on those lists (sheds, decks, steps, AC pads and foundation beds) are the first places we check.

A burrow is active when its walls are smooth and the dirt is hard packed, fresh soil sits at the entrance, and droppings or tracks lead to and from it. eXtension states it directly: “Active burrows have smooth walls and hard packed dirt.”

Look around the hole, not just into it:

• Fresh soil. A new fan of loose, darker dirt at the opening means recent digging.
• Runways. Rats use the same routes nightly, wearing paths through grass and leaving dark greasy marks along foundation walls (eXtension).
• Droppings, gnawing and tracks. Nebraska Extension notes “feces, gnawing and tracks may be found along runways between the den and sources of food and water.” Follow the runway and it usually leads to whatever is feeding them.

A burrow with crumbling edges, weeds growing in the opening and no fresh soil may be old. Even so, an empty burrow next to the house is worth reporting, because the conditions that drew rats there have not changed.

Burrows form near foundations because the soil against a house is sheltered, often hidden by shrubs, a stoop or an AC pad, and sits a short trip from food and water. A foundation wall also gives a rat one solid side to dig along.

The house itself becomes part of the burrow. A tunnel that starts in a planting bed can follow the footing down and come up under a slab, a porch or into a crawl space.

So a hole in the flower bed against the house is a different problem from one at the back fence. Near the foundation, the question is no longer only where the rats live but whether they have reached the space under your floor. Our crawl space rodent control work starts with exactly that check.

Rat burrows are treated by dealing with the rats first and closing the holes second. eXtension’s guidance is that once all the rats are out, the burrow can be filled with concrete or sand.

This is not a pour-it-down-the-hole job. EPA rules restrict the rodenticides sold to homeowners: the strongest anticoagulants are registered only for professional pest control, and bait stations are required wherever children, pets or wildlife could reach the bait. Burrow fumigants are highly toxic, and University of Nebraska-Lincoln Extension says only professional structural pest control operators should use them in or around buildings.

What a professional treatment looks like for us:

1. Inspection to find every opening, including concealed escape holes.
2. Burrow and nesting-site treatment, with exterior bait stations and trapping.
3. A follow-up visit to recheck stations and confirm the burrows are no longer used.
4. Closing the confirmed-empty burrows and the gaps that led to them.

Sealing the house still matters because treating a burrow removes today’s rats, not the reason rats chose your foundation. UC IPM’s rat guide calls exclusion, or “building them out,” “the most successful and longest-lasting strategy for rat control around structures.”

At the foundation, University of Nebraska-Lincoln Extension describes several defenses against burrowing:

• Foundation walls extending at least 36 inches below ground
• A curtain wall of concrete or 1/4-inch wire mesh, which can be added to existing buildings (mesh generally lasts 5 to 10 years)
• A strip of coarse gravel at least 2 feet wide and 6 inches deep against the foundation

Most of that is construction work. What we do is seal the vents, gaps and foundation openings rats reach once they have dug in close, through our rodent proofing service.

Call for rat control when a burrow shows fresh soil, smooth packed walls or runways, when holes sit against the foundation, or when you find rat droppings inside the house or garage. Any one of those means rats are living on the property now.

It is also time to call if:

• You have found more than one hole, since one burrow system can have several entrances
• Holes reappear after you fill them
• You hear gnawing or movement under the floor at night

Chesapeake Rodent Control’s published price for rat treatment is $150 to $220 per visit, and the exact figure is confirmed on the free callback, before you book. Professional rat control from us covers the inspection, burrow treatment and follow-up from start to finish.