Ridge vent vs gable vent: should you have both?
Short answer. Usually not. Gable vents are wall louvers at the ends of the attic that mostly move air across the upper attic, while a ridge vent pulls air up from the soffits along the whole roof; when both are open, the ridge vent tends to draw from the nearby gable vents instead of the eaves. Many vent manufacturers advise closing gable vents from the inside once a ridge vent and soffit intake are in place.
How gable vents behave
Gable vents rely mostly on wind. When wind blows toward one gable, air enters there and exits the other, sweeping the top of the attic. On still days they do little. Because they sit high, they make poor intake for a ridge vent: air takes the shortest path from gable to ridge and skips the eaves, where heat and moisture collect along the lower deck.
When gable vents are fine
- Older homes with no soffits and no ridge vent, where gable vents are the only ventilation and adding intake is not practical.
- Attics too small or chopped up for a ridge vent.
How to close them properly
Leave the exterior louver in place for appearance and block it from the attic side with rigid foam or plywood, sealed at the edges. That also keeps out wind-driven rain during Georgia's sideways summer storms. Do this only after confirming the soffit intake is open and sized to the ridge vent.
Signs of a short circuit
- A hot lower attic near the eaves while the area near the gables stays cooler.
- Stained decking low on the slopes.
- Dust trails or debris streaking from the gable vents toward the ridge.