Animals who take up residence under a deck, crawl space or shed are often capable diggers.
If you put up a fence to keep them out, be sure to extend wire meshing out in an “L” shape at or beneath the ground. L–footer style fencing (PDF) will also keep wildlife out of yards and gardens. L–footers can be homemade using fencing material or purchased from the sources listed in our Guide to Retail Sources for Products to Resolve Wildlife Conflicts (PDF).
Ideally, these footers are buried about a foot deep and are extended out at a 90-degree angle a foot or more to present a horizontal barrier to any animal who decides to dig underneath the fence.
What size mesh?
The size of the wire mesh you choose depends on the size of the animals you’re trying to exclude. Typically two by three-inch fencing, galvanized or plastic-coated for resistance to the weather, will exclude woodchucks, raccoons and opossums, but not small rodents. One-by-one-inch galvanized wire should be used if you want to keep out smaller animals.
It doesn’t have to be buried to work
It is not absolutely necessary that the L-footer be buried. You can lay it on the surface if digging is made impossible by foundation plants, roots or rocky soil. Use landscaping staples from garden supply outlets to hold the footer tightly down. Then cover it with soil or mulch or allow grass to grow through it until it is incorporated into the turf.
Make a fence, not a trap
If you are trying to keep an animal from living under a deck or shed, make sure that you don’t accidentally trap the animal. When installing the footer:
- Fence all but one opening (large enough for the target animal, of course).
- Monitor for activity by placing some material (try propping a few sticks or stuffing some loosely wadded newspaper) in the opening and checking every day to see if it’s been pushed aside or crushed.
- If you see no signs of activity for a number of days, finish installing your fence. Keep a close eye on the fenced-in area though and make sure no animals have been inadvertently trapped. (In some situations, you might want to use a one-way door to allow animals to evict themselves, but not get back in.)
Note of caution: Any time you make changes to an area where animals might be denning, you must examine that area daily after the animal has been excluded to make sure they have not tried to get back in or that young are not trapped inside.
Some animals, such as groundhogs, hibernate. If you are excluding an animal who hibernates during the colder months, make sure that you don’t turn their dens into tombs when they wake in warmer months, well after you have stopped monitoring the area where you’ve erected the fence.