What does the screen or filter inside a ridge vent do, and do you need an extra guard?
Short answer. The screen or filter inside a ridge vent, usually a nonwoven fiber mat or plastic mesh, keeps out insects, wind-driven rain and debris, and the vent's net free area rating already accounts for it. Most homes do not need an extra guard, but if squirrels are chewing at the ridge, a metal vent or professional exclusion work makes more sense than adding mesh.
Types of internal screens
- Nonwoven fiber filter: a felt like mat inside many rigid and rolled vents. Good at stopping wind-driven rain and fine insects.
- Plastic mesh: molded or attached screens with small openings.
- Aluminum screen: on older exposed metal ridge vents.
The code keeps vent openings between 1/16 and 1/4 inch, small enough to stop wasps and mice but large enough not to clog instantly.
How screens age
- Pollen and dust: Georgia's spring pollen coats everything, including vent filters, which can slowly restrict airflow.
- Debris: oak tassels and pine needles collect at the ridge on heavily wooded lots.
- UV and heat: plastic mesh can become brittle.
Ridge vent filters are not designed to be cleaned from outside, and removing caps to get at them usually ruins the caps. If a vent is badly clogged or damaged, it is replaced, often with the roof.
When an extra guard comes up
- Squirrels: they can chew through plastic vents at the ridge ends to reach the attic. Fix the entry with proper end closures, sometimes a metal vent, and have a wildlife professional handle exclusion.
- Wasps: nests at the ridge usually mean a missing end plug, not a bad screen.
- Bats: exclusion has timing rules; use a professional.
Adding mesh over a vent can choke its airflow. See trees and your roof and pine needles and leaves on the roof.