Rodent Exclusion: Sealing Rats and Mice Out of Your House
Trapping removes the rodents inside. Exclusion stops the next ones from getting in. We walk the whole exterior from foundation to ridge, find every gap a rat or mouse can use, and close it with materials they cannot chew through. Exclusion is the step that makes every other fix last.
How small a gap is too big
| Animal | Gap it can pass through | Where it usually enters |
|---|---|---|
| House mouse / deer mouse | About 1/4 inch | Utility penetrations, door sweeps, weep gaps |
| Roof rat | About 1/2 inch | Roof vents, eave gaps, roof-to-wall joints, dormers |
| Norway rat | About 1/2 to 3/4 inch | Crawl space vents, foundation cracks, pipe and conduit holes, dryer vents |
A rat's skull is the only part that has to fit. If the head goes through, the body follows.
Where we look
- Roofline: gable vents, ridge vent ends, roof jacks, gaps where a lower roof meets a wall, unscreened eave blocks, chimney flashing
- Walls: dryer and bath fan terminations, hose bib and cable penetrations, gaps behind trim, siding damage near grade
- Foundation: crawl space vents with rusted or torn screens, the crawl access door, holes around sewer, water and gas lines, cracks in block or concrete
- Inside the crawl space: ductwork boots, plumbing holes through the subfloor, open chases into wall cavities that lead to the attic
- Landscape conditions: tree limbs touching the roof, ivy on walls, wood piles against the foundation — not things we seal, but they go in the report
Materials that hold up
Expanding foam alone does not stop rats; they chew through it in a night. We use:
- Galvanized hardware cloth (1/4-inch mesh) behind vents and over openings that must stay open for airflow
- Heavy-gauge vent covers replacing flimsy plastic or torn screen vents
- Copper or stainless steel mesh packed into irregular gaps, then sealed over with sealant or mortar
- Sheet metal flashing at roof-to-wall joints and along damaged fascia
- Mortar or hydraulic cement for foundation holes and cracks around penetrations
- One-way exclusion doors at the main active entry, left in place for several days so rodents can leave but not return, then sealed permanently
The process
- Exterior and interior inspection with every entry photographed and marked on a simple sketch of the house.
- Sealing, usually in one day. Roof work is done from ladders or roof anchors; we do not need to remove shingles.
- Tracking. We lay a fine tracking powder or monitoring stations at former runways.
- Follow-up visit at seven to fourteen days. If anything has crossed, we find the missed gap and seal it at no charge.
What exclusion costs by house type
| Home type | Typical exclusion cost |
|---|---|
| Single-story rambler, simple roof | $900 – $1,800 |
| Split-level or two-story, average roof | $1,500 – $2,800 |
| Older home with many vents, dormers or damaged fascia | $2,200 – $3,500 |
Exclusion is priced on its own and can be done without any cleanup. If droppings are heavy, we recommend rodent cleanup once activity stops.
Exclusion questions
Do you set traps or use poison?
No. We seal the structure. Trapping is done by a pest control company, and we work with whichever one you prefer. We advise against poison bait inside the house: poisoned rodents often die inside walls, and the odor can last for weeks.
Will sealing trap rats inside?
That is why the main entry gets a one-way door first and why trapping runs at the same time. Any animal still inside either leaves through the door or is trapped.
How long does exclusion last?
Metal and mortar repairs last as long as the parts of the house they are attached to. New gaps appear when siding is replaced, a new vent is cut or a pipe is added, so we recommend a quick exterior check every year or two.