Mouse exclusion works best when active routes are identified first and then sealed with materials that cannot be easily gnawed through. Small gaps around pipes, doors, or siding may be enough for entry, but sealing blindly can trap animals inside the structure.
Confirm the route before sealing
Look for rub marks, droppings, gnawing, and gaps near where activity is found. Observing the route for several days helps avoid spending time sealing cracks that are not connected to the problem.
Use gnaw-resistant materials
Appropriate metal mesh, sheet metal, and reinforced sealants work better than foam alone where mice can reach the opening. The material must be secured and compatible with piping, ventilation, and normal building movement.
Do not block ventilation or drainage
Vents, grilles, and weep openings have a purpose. Protect openings with appropriately sized mesh without sealing systems that need to move air or drain water.
Make sure animals are not trapped inside
If there is activity in walls, an attic, or garage, combine exclusion with removal and sanitation before closing the last exit. Sealing while animals remain inside can drive them into occupied areas or create odor if one dies in a cavity.
Sources
- U.S. Environmental Protection Agency (EPA) — Integrated Pest Management — Integrated pest management using sanitation, exclusion, monitoring, and targeted control.