Keeping rodents out is about exclusion — finding and sealing the gaps they squeeze through. A mouse fits through a hole the size of a dime, and a rat through a quarter-size gap, so the goal is to seal every opening with materials they cannot chew: steel wool, copper mesh, and sealant, plus a solid door sweep. Trapping handles the rodents already inside, but if you do not seal the entry points, new ones simply take their place. Work the perimeter methodically.
What you'll need
- A flashlight
- A caulk gun
- Work gloves
- A ladder
- Snap traps for any rodents already inside
Recommended parts & supplies
- Pest-proof door sweep — closes the under-door gap, the most common entry point
- Copper mesh / steel wool fill — pack into gaps — rodents cannot chew through it
- Gaps and cracks expanding foam sealant — seals around pipe and wire penetrations
- Snap traps — remove the rodents already inside before you seal up
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Step by step
- 1
Inspect the outside of the house
Walk the full perimeter with a flashlight, low and slow. Rodents enter where utilities pass through the wall (water, gas, AC lines, cable), where the foundation meets siding, around crawlspace and attic vents, under garage door corners, and at rooflines and soffits. Look for gnaw marks, greasy rub trails, and droppings that point to an active route.
- 2
Check the roofline and attic
In Houston, roof rats are common and get in high up. Check where tree limbs touch the roof, along the fascia and soffit, around the chimney, and at vent openings. In the attic, look for droppings, chewed insulation, and daylight showing through gaps. Trim back any branches within a few feet of the roof — they are a highway inside.
- 3
Trap the rodents already inside first
Before you seal, remove what is in there, or you will trap animals inside your walls. Set snap traps along walls where you see droppings, baited with peanut butter, with the trigger end toward the wall. Give it several nights. Sealing a house with active rodents still in it leads to a dead-animal smell in the walls.
- 4
Pack gaps with steel wool or copper mesh
For every gap up to a couple of inches, stuff it tightly with copper mesh or steel wool. Rodents cannot chew through metal fiber the way they chew through foam or caulk alone. Push it firmly into the opening so it stays put — this is the core of rodent-proofing.
- 5
Seal over the fill with foam or caulk
Cap the packed metal fill with an expanding pest-block foam or exterior sealant to lock it in place and close the gap to weather. Around pipe and wire penetrations, pack the mesh first, then foam over it. For larger holes, back the opening with hardware cloth before sealing.
- 6
Add door sweeps and close the last gaps
Fit a rodent-proof door sweep on every exterior door, including the door from the garage into the house — the under-door gap is the single most common entry point. Replace worn weatherstripping, cover vents and weep holes with fine hardware cloth, and do a final flashlight pass to catch any daylight you missed.
When to call a pro
Call a professional if you keep hearing scratching in the walls or ceiling after sealing, if you find heavy droppings or a nest, or if rodents are getting into hard-to-reach areas like a two-story roofline or a sealed attic. A large or repeat infestation usually means multiple hidden entry points and possibly a nest, and pros have the tools, cameras, and experience to find them all. Rodents also carry disease and their droppings require careful cleanup — a pro handles removal, full exclusion, and attic sanitation safely. Never poison rodents inside living space, where they die in walls; leave baiting decisions to a licensed technician.
Get a free quote from a local pro
No obligation — a licensed, insured local Houston partner will reach out. Available 24/7 for emergencies.
How to Seal Entry Points and Keep Rodents Out of Your Home — FAQ
How small a gap can a mouse get through?
What is the best material to seal rodent entry points?
Should I seal the house before or after removing the rodents?
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