Rat and mouse articles · Updated
Steel wool vs. copper mesh for sealing out mice and rats
Both work as a plug when packed tight and sealed over. Copper mesh is better outdoors because it doesn't rust; steel wool is cheap and fine indoors. For gaps bigger than about an inch, vents and anything on the roofline, use hardware cloth or sheet metal instead.
Rodents chew through foam, caulk and wood. They don't chew through metal. That's why steel wool and copper mesh are the go-to materials for small gaps around pipes and wires. Here's how they compare, how to install them, and when you need something stronger.
Steel wool
Steel wool is cheap and easy to find. Packed tightly into a gap, it's rough enough that a mouse won't chew through it. Its weakness is rust. Outdoors or anywhere damp, like under a sink or near an AC condensate line, it rusts, crumbles and leaves orange stains on brick and siding. Indoors and dry, it holds up fine.
Copper mesh
Copper mesh is a knitted copper fabric sold in rolls for pest exclusion. It costs more than steel wool but doesn't rust, so it's the better choice outside: around the AC line set, the hose bib, the gas line and cable entries. It's also easier to work with; you can tear off a strip and stuff it in. Over time it darkens, but it doesn't crumble.
Something in the attic or the garage?
Want a local rodent technician to look at it? Same-day appointments are often available. (972) 325-9652
How to install either one
The plug only works if it's tight and sealed over. Here's the method:
- Wear gloves; both materials have sharp ends
- Pack the material in firmly until it fills the gap with no loose spots
- Leave it slightly recessed from the surface
- Seal over it with an exterior sealant or caulk so rodents can't pull it out
- On larger gaps, use foam as a backer behind the mesh, never on its own
When you need hardware cloth or flashing
Stuffing works for small gaps, up to about an inch. For anything bigger, or anything that needs airflow, use galvanized hardware cloth or sheet metal. Texas A&M AgriLife training material lists hardware cloth among the standard exclusion tools.
- Gable, ridge and soffit vents: quarter-inch hardware cloth screwed over the opening
- Roof returns and soffit corners: sheet metal flashing cut to fit, plus mesh in the gaps
- Weep holes: weep vent covers made for brick, not stuffing
- Shed and deck edges: hardware cloth buried in an L-shape
- Garage doors: a new bottom seal and side stops
What about foam and caulk alone?
Spray foam and caulk by themselves won't stop a rodent. They're soft, and a rat or mouse will chew through them, sometimes in a single night. They're useful as backers and for sealing over mesh, not as the barrier.
Why foam fails in Texas heat
Spray foam has another weakness in Plano: sun and heat. Exposed foam on the west and south sides of a house breaks down, shrinks and crumbles over a few summers, leaving the gap open again. Metal doesn't have that problem. If you use foam at all, keep it behind the mesh and cover it with sealant so the sun doesn't reach it.
How small a gap matters
AgriLife's material says a mouse can get through a quarter-inch crack or a hole the size of a dime, and a rat through a half-inch crack or a quarter-size hole. If you can fit a pencil into the gap, a mouse can probably use it. The entry points article shows where those gaps usually are on a Plano house.
Where to use it on a Plano house
These are the spots where stuffing material makes sense:
- Around the AC line set where it enters the brick
- Around the hose bib, gas line and cable entry
- Under the kitchen and bathroom sinks, around supply and drain pipes
- Behind the dishwasher and stove, where lines come through the wall
- Around the water heater flue in the garage ceiling, using metal flashing for the larger gap
What you'll need
For a weekend of ground-level sealing: a roll of copper mesh, a tube or two of exterior sealant and a caulk gun, a pair of heavy gloves, a flathead screwdriver or putty knife to push the mesh in, and a flashlight. Add quarter-inch hardware cloth, tin snips and screws if you're covering a vent or a larger hole. A small mirror on a stick helps you see behind pipes under the sink.
Checking your work
A week after sealing, look at each spot. If the mesh has been pulled out or the sealant chewed, a rodent is still testing it, and that spot may need hardware cloth or flashing instead. Set a few snap traps nearby. If you're still catching mice after everything is sealed, there's a gap you haven't found yet.
Do it yourself or hire it out
Ground-level gaps around pipes and lines are a reasonable weekend job with copper mesh and sealant. Roofline work is different. Roof returns and gable vents on a two-story are ladder work, and they're where roof rats get in. If the gaps are up high, or you keep catching rodents after sealing what you can reach, entry point sealing is the next step. Sealing usually follows mouse control trapping.
Something in the attic or the garage?
Ready to have the gaps found and closed? Call and describe what you're hearing or finding. (972) 325-9652
Common questions
Can mice chew through steel wool?
Not when it's packed tight and sealed over. Loose or rusted steel wool can be pulled out.
Is copper mesh worth the extra cost?
Outdoors, yes. It doesn't rust or stain the brick.
Can I use steel wool in weep holes?
Weep holes need to drain water. Use weep vent covers made for brick instead.
What size hardware cloth should I use?
Quarter-inch hardware cloth keeps out mice and rats and still lets vents breathe.
Can I paint over copper mesh?
Once it's sealed over, you can paint the sealant to match the brick or trim.