Do ridge vents need a critter guard?
Short answer. Most modern shingle-over ridge vents already have built-in filter fabric or mesh that keeps out insects, birds and wind-driven debris, so a separate critter guard is rarely needed on a properly installed vent. Animals usually get in at unplugged ends, crushed or torn sections, or older vents without filters, and those spots are fixed with end plugs, mesh or vent replacement.
How critters get into ridge vents
- Open ends: where the vent was cut and not plugged, or where the end cap shingle has slipped.
- Torn or crushed sections: overdriven nails, foot traffic or hail open gaps in the vent body.
- Old vents: some older metal ridge vents have louvers with openings large enough for wasps and bats.
- Squirrels: they chew the plastic or the cap shingles at ridge ends, especially near overhanging limbs.
What a fix looks like
- Seal open ends with the manufacturer's end plugs, then a cap shingle over them.
- Replace damaged sections rather than stuffing them with foam or steel wool, which also blocks airflow.
- Where squirrels are chewing, trim branches back from the roof and repair entry points with metal mesh that keeps openings at 1/4 inch or smaller.
- For bats, use a wildlife professional who can exclude them at the right time of year rather than sealing them inside.
What not to do
Do not staple screen over the top of the ridge vent or spray foam into it. That blocks the exhaust and can void the vent's warranty. The building code calls for vent openings between 1/16 and 1/4 inch, which filtered vents already meet.
Related reading: trees and your roof and ridge vent vs box vents.