Anyone who lives near salt water knows what the air does to metal. Mailboxes flake, grill grates pit and the screws on a deck turn orange. The same chemistry works on the quiet metal around a house: vent screens, flashing, foundation grates and the little louvers on a crawl space.
Rodents benefit. Mice squeeze through slots barely thicker than a pencil, while rats want roughly a half inch. Rust does not need to remove a whole screen to make an opening. It only has to eat a hole at one corner.
Why corrosion happens faster near the shore.
Salt in the air settles on metal and holds moisture, which speeds rust. Wind carries it farther than you might think, so even houses a short distance from a bay or marsh can see effects. We cannot say how far inland the effect reaches for any given address, but if you live on the South Shore it is reasonable to check your metal more often than a house inland would need to.
Thin steel suffers most. Stamped vent covers and cheap hardware-store screens are made of metal only a fraction of a millimeter thick, so a few seasons of salt spray can turn them to lace.
The places to check.
- Foundation vents and crawl space louvers, which sit low and catch the most spray and splash.
- Soffit and gable vents, where screens can rust loose at the corners.
- Dryer and bath exhaust caps, which have flappers that stick open when corroded.
- Flashing at roof edges, chimneys and wall joints, where rust can open a seam.
- Fasteners that hold covers on, since a rusted screw lets the whole cover fall away.
Run a screwdriver gently across each screen. If it flakes, crumbles or bends easily, the part has weeks left, not years.
Choosing a metal that lasts.
| Material. | Strength near the coast. | Notes. |
|---|---|---|
| Plain steel mesh. | Poor. | Rusts quickly and leaves gaps. |
| Galvanized mesh. | Fair. | Zinc coating delays rust; wears off at cut edges. |
| Coated or vinyl-coated steel mesh. | Good. | Coating protects the wire; check for nicks. |
| Stainless steel mesh. | Best. | Costs more and lasts the longest. |
| Plastic mesh. | Not recommended. | Rodents chew through it. |
Frames matter as much as mesh. A stainless screen in a rusted frame still falls apart, so replace the whole assembly when the frame shows damage.
If it is the middle of the night, call anyway.
(888) 686-4821Sealing around the metal.
Any spot where a line pierces the wall leaves a ring of space, and that ring counts as part of the problem. Fill small gaps with mortar-grade sealant or a metal collar, not expanding foam. Foam is easy to chew and breaks down in sunlight. Our rodent-proofing page describes the materials we use.
A yearly routine that takes an hour.
Put two dates on the calendar. In spring, once storms have passed, walk the exterior and test every screen and cover. In early autumn, before nights turn cold, repeat the walk and fix whatever you found in spring that you did not get to. Keep a short list on your phone of what each vent is and when it was last replaced.
- Photograph each vent when it is new, so you can compare later.
- Carry a small tin of touch-up sealant for small chips in coated mesh.
- Keep spare screens in the size you use most.
- Replace anything that flakes, not just anything that fails.
Special cases: older houses and additions.
Additions, porches and enclosed decks often have vents installed by different people at different times. Their screens may not match the rest of the house and may have been made of whatever was on hand. Treat each one as its own job. If you are not sure what is behind a panel, ask a technician to look, since an unscreened opening in a hidden space is a common entry.
If you find a gap and are not comfortable on a ladder, call. The work usually takes a short visit, and the inspection page explains how the estimate is built.
Before you call: soak first, wipe second.
These federal pages are summarized in loose terms. For health questions, a doctor is the better source than a pest company.
- Your job is to dampen the mess first and move it second, so wetting always comes before sweeping.
- Airing a closed space for thirty minutes is the CDC's first step before cleanup begins.
- Rubber, latex or vinyl gloves go on before you touch anything stained, and hand washing finishes the job.
- A mix of one part bleach to nine parts water is the CDC's home recipe, and it should be made fresh each time.
- Ordinary garbage service takes the bag, and any reusable tool you used gets rinsed.
- A fever that will not break, or a struggle to catch your breath, after exposure warrants a doctor.
Reading list from federal agencies.
Each link goes straight to the agency's own website.
- Hantavirus precautions from the CDC: A trio of jobs for keeping rodents away: seal, trap and clean.
- CDC walkthrough for rodent mess: The reasoning against brushing or vacuuming dry rodent waste.