What is a ridge vent guard?
The parts that do the guarding
- Filter fabric or mesh: a nonwoven fabric or screen on the underside of the vent that blocks insects, dust and blowing debris. Common on rolled vents.
- External baffle: a raised lip along the outer edge of the vent. Wind hitting it deflects up and over, creating low pressure that pulls air out instead of pushing rain in.
- Internal weather baffles: walls inside the vent that force rain to change direction several times before it could reach the slot.
- End plugs: closures for the open ends at the gable rakes, a common entry point for wasps and squirrels.
- Add-on metal guards: some homeowners fasten mesh or metal over a plastic vent to stop squirrels chewing in. Done wrong, this chokes the airflow.
When you might need one
If you see daylight through the vent from the attic and wasps nesting in it, or small water spots below the ridge only in sideways rain, the vent probably lacks a filter or baffle. Older aluminum ridge vents with open louvers are the usual suspects. In North Georgia, squirrels chewing into plastic ridge vents is another reason homeowners go looking for a guard.
Often better than a retrofit
Replacing an unbaffled or damaged vent with a modern shingle-over vent that has a filter, an external baffle and proper end plugs is often cheaper over the life of the roof than adding covers on top. Whatever you add, it must not reduce the vent's net free area below what the attic needs, or you trade a pest problem for a heat and moisture problem. See ridge vent vs box vents and roof ventilation basics.