What mesh size should a rat wall use?
Quarter-inch galvanized hardware cloth. Larger openings let mice through. Thinner, uncoated wire rusts in soil and becomes a hole again.
Rat walls What is a rat wall, and how is it installed?
If the animal's plan is to dig, a trap on the lawn is the wrong tool. A buried metal apron makes the tunnel a dead end.
Key facts
- Use 1/4-inch galvanized steel hardware cloth. The openings are too small for rats and mice.
- Dig a narrow trench around the structure or the area you need to protect.
- A practical depth is at least 6 to 12 inches, deep enough to meet the tunnels you have.
- An L-footer, the bottom bent 90 degrees outward, makes digging under the mesh much harder.
- Galvanized steel resists soil moisture better than plain wire.
- The barrier is non-toxic and, once backfilled, mostly invisible.
What problem does it solve?
Rats, mice, groundhogs, skunks, and other diggers do not need a door if they can go under a foundation, deck, shed, or raised bed. A rat wall is the physical answer. Animals start a tunnel, hit metal, and stop. Extension guidance on rodent exclusion has recommended buried mesh for this reason for years.
How do you install one?
Measure the perimeter you actually need to protect. That might be a deck, not the whole property line. Dig a narrow trench at the base. Set 1/4-inch galvanized hardware cloth in the trench and fasten the top to the structure, framing, skirting, or foundation, so there is no slot above the mesh.
For a stronger version, bend the bottom of the cloth outward into a horizontal foot before you bury it. Backfill and compact the soil. Sod or mulch can cover the top. The metal stays down there.
Why this mesh, and why not poison?
Quarter-inch openings stop rats and smaller rodents from squeezing through. Galvanized coating handles damp soil better than untreated steel, so the barrier is a multi-year object, not a one-season screen. It does not put toxic bait where pets and owls can find it.
Depth and the outward bend are the details people skip. A shallow skirt that an animal can undermine is just a fence that failed underground. Match the burial to the digging you are seeing. Groundhog work often wants a deeper apron, on the order of 12 to 18 inches. A rat at a deck skirt is often in that 6 to 12 inch range. The inspection should pick the depth, not a guess.
What will a rat wall not stop?
A rat wall does not remove animals already living under the shed. They have to be out first, or you have fenced them in. It also does not seal a soffit. Digging and climbing are different doors. Use it where the evidence is a hole in the dirt.
What changes by region?
Northeast Indiana
Around Fort Wayne, the usual places are deck skirts, shed floors, and foundations on lots that back up to a field or a ditch. We pair a rat wall with whatever is already denning there, including groundhogs and skunks, and we do not bury mesh over an occupied burrow.
Central Ohio (coming soon)
The install is the same in Central Ohio: 1/4-inch galvanized cloth, a real trench, and an outward foot if the soil is easy to dig.
Common questions
How deep does the trench need to be?
Often at least 6 to 12 inches for rats along a deck or foundation. Deeper digging, such as a groundhog under a footing, calls for a deeper apron, commonly 12 to 18 inches. Match the hole you have.
What is an L-footer?
The bottom of the mesh bent outward at a right angle before it is buried. An animal digging down the wall hits the horizontal shelf and has to back up. Straight vertical mesh is easier to undermine.
Can I install one if something is still under the deck?
Not as the first step. Confirm the space is empty, then bury the barrier. Sealing an animal in is how you get odor and a new exit through the floor.