An opossum denning under a deck, shed, or porch is one of the most common wildlife calls homeowners deal with, and it is also one of the easiest to resolve without hiring anyone or harming the animal. Opossums are not diggers and do not create their own burrows; they use whatever cavity is already available — a gap under a porch, a crawlspace vent knocked loose, the underside of a shed with a rotted skirting board. That dependence on existing gaps is exactly what makes exclusion effective: close the gap correctly and the problem does not come back.
Confirm the Animal Is Actually an Opossum
Before doing anything else, verify what is actually living under the structure. Skunks and groundhogs use similar spaces and require different handling — a groundhog, for instance, actively digs and will simply excavate a new entrance next to a sealed one, a behavior covered in our guide to groundhog burrow systems. An opossum den site usually shows minimal digging, a smooth entry path worn into grass or mulch, and little accumulated debris, since opossums do not cache food or bedding materials the way squirrels and chipmunks do.
Timing Matters More Than Almost Anything Else
The single biggest mistake in DIY exclusion is sealing an entrance while young are still inside and unable to follow their mother out. Female opossums carry joeys in the pouch for about two months and then on their back for several more weeks; if you seal an entrance during this window, you risk trapping and killing dependent young inside a wall or crawlspace, which creates both an animal welfare problem and eventually an odor problem. Watch the den for a few evenings before doing any permanent sealing, ideally during the season when litters are less likely to be denned, and never seal an opening during spring or mid-summer without being reasonably confident the den is not currently occupied by a nursing female.
Sprinkle a thin layer of flour or sand across the entrance at dusk and check it the next morning. Outbound-only tracks over one or two nights, with no fresh tracks going back in, are a reasonable sign the den is empty and safe to close.
Encouraging a Voluntary Exit
Opossums are highly tolerant of mild disturbance and will often relocate on their own if the den site stops feeling secure. A bright work light left on near the entrance overnight, an ammonia-soaked rag placed just inside the opening, or simply increased human and pet activity near the area for a few days is usually enough to push a healthy adult to move to an alternate den, which most opossums maintain several of within their home range. This approach is slower than trapping but avoids the stress, cost, and legal complications of live-capture, and it is the method recommended by most extension wildlife-damage programs, including the wildlife damage handbook maintained through the University of Nebraska's Internet Center for Wildlife Damage Management.
Sealing the Gap Correctly
Materials That Actually Hold Up
Once the den is confirmed empty, the repair needs to resist an animal that can push, dig shallowly, and squeeze through surprisingly small gaps — an adult opossum can fit through an opening not much larger than its skull. Rigid hardware cloth with quarter-inch or half-inch openings, not flexible chicken wire, holds up to repeated pressure and does not deform. Wood lattice alone is not sufficient; opossums and other animals can chew or pry through it within a season.
Bury or Angle the Edge
Any animal capable of even light digging will test the bottom edge of a new barrier first. Burying hardware cloth six to eight inches below grade, or bending the bottom foot of material outward in an L-shape away from the structure, prevents an animal from simply pushing underneath the new barrier at ground level. This single detail is the difference between an exclusion that lasts for years and one that fails within a few weeks.
What to Do If You Are Not Sure
If you are uncertain whether young are present, whether the animal is healthy, or whether the space you are dealing with is more complex than it looks, a licensed wildlife control operator or your state wildlife agency can advise or assist for a modest fee. This is a different situation from an injured animal emergency — for that, our guide on what to do with injured wildlife in the first hour covers who to call and why speed matters. For a healthy adult simply using your deck as shelter, patience and a properly sealed barrier solve the problem permanently, and the animal usually relocates within your neighborhood rather than being displaced any real distance.