Something keeps tunneling under the concrete slab of my garden shed. I’ve filled it in, but every morning it’s back—and I’m worried it could damage the foundation. What would you do?

Finding a tunnel under the concrete slab of your garden shed can be alarming and puzzling. It’s natural to wonder what animal might be living there while also worrying about possible damage to the structure. Even a small burrow can weaken the base of the shed, and leaving it untreated may eventually lead to cracks or an uneven floor that requires expensive repairs.

This guide explains how to deal with the situation step by step. You’ll learn how to figure out which animal is responsible, protect your shed, and reduce the chances of the problem happening again.

1. Identify the Animal Responsible

Start by determining what animal is digging beneath your shed. Groundhogs, also known as woodchucks, are strong diggers and typically leave entrances about 6–12 inches wide with a pile of dirt nearby. Their tracks are usually around 2–3 inches across and show five toes. However, other animals such as skunks, raccoons, or armadillos can also create burrows. Setting up a trail camera can help capture nighttime activity and reveal the culprit.

2. Understand Why Groundhogs Choose Your Shed

Groundhogs are simply searching for a safe and comfortable shelter. A shed provides a dry roof and protection from predators, while nearby gardens or lawns offer a reliable food source. Their burrow systems often contain several chambers used for sleeping, raising young, and even separate areas for waste. Understanding this behavior can help you make the area less attractive to them.

3. Check for Structural Issues

A single entrance hole may lead to a much larger underground network. Some burrow systems can stretch from 8 to 66 feet long and reach depths of up to 5 feet. This type of digging can weaken the soil supporting the concrete slab. Inspect your shed for warning signs such as doors that no longer close properly, noticeable tilting, or gaps forming between the slab and the structure. Catching these problems early can prevent costly repairs.

4. Use Temporary Barriers

To slow or stop digging while planning a permanent solution, place heavy rocks or paving stones over the opening. You can also cover the hole with wire mesh (hardware cloth) buried about 12 inches deep and extending outward. These measures may discourage further digging for the time being.

5. Make the Area Uncomfortable for Burrowing

Groundhogs prefer quiet, undisturbed environments. Devices such as motion-activated sprinklers, predator-scent repellents, wind chimes, or vibrating stakes can make the area less appealing. By creating noise, movement, or unfamiliar smells, you may encourage the animal to move somewhere else.

6. Consider Live Trapping

If deterrents don’t work, a live trap might be necessary. Choose a trap roughly 12×12×32 inches in size and place it close to the burrow entrance. Fresh vegetables such as lettuce, carrots, or apples can work well as bait. Be sure to check local wildlife regulations before trapping, and inspect the trap daily.

7. Close the Burrow Properly

Only seal the hole after confirming the animal is no longer inside. Fill the tunnel entrance with gravel or a mixture of soil and cement. Then cover the area with heavy-duty wire mesh buried about 12 inches deep to discourage future digging.

8. Install a Protective Barrier

A long-term solution is to create a dig-resistant barrier around the shed. Use galvanized wire mesh buried roughly 12 inches underground and bend it outward in an “L” shape to stop animals from tunneling underneath. Extending the mesh about 24 inches above ground can also help prevent climbing.

9. Repair or Strengthen the Concrete

After the animal has been removed, inspect the concrete slab for cracks or weak spots. Minor cracks can usually be filled with standard concrete repair compound, but more serious damage might require additional concrete reinforcement or steel support. Regular checks can help avoid larger problems later.

10. Reduce Yard Attractions

Make your yard less inviting to burrowing animals. Keep grass trimmed, remove piles of debris, and protect gardens with fencing. Some homeowners also use natural deterrents such as garlic-based sprays or hot pepper mixtures. When food and shelter are limited, groundhogs often relocate.

11. Seek Professional Help if Needed

If trapping efforts fail or if the shed shows major structural issues, it may be time to call professionals. Wildlife control specialists can safely handle the animal, while structural experts can evaluate the stability of your shed and recommend proper repairs. Professional help can prevent further damage and give you peace of mind.