What are the types of attic ventilation?
Short answer. Attic ventilation comes in two halves: intake vents low on the roof, such as soffit and edge vents, and exhaust vents high on the roof, such as ridge vents, box vents, turbines, gable vents and powered fans. A third approach, the unvented attic, skips vents entirely by insulating the underside of the roof deck.
Intake vents
- Soffit vents: perforated panels, strip vents or individual louvers in the underside of the eave. The most common intake.
- Edge intake vents: a vent built into the lowest part of the roof, for houses with little or no overhang.
- Fascia vents: a narrow slot along the top of the fascia, used on some homes with shallow eaves.
Exhaust vents
- Ridge vents: a continuous vent under the cap shingles along the peak. Even airflow, low profile.
- Box or static vents: square hooded vents in a row near the ridge, common on hip roofs with short ridges.
- Turbines: spinning vents that use wind to pull more air when it blows.
- Gable vents: louvers in the end walls that act as intake or exhaust depending on the wind.
- Powered attic fans: electric or solar fans that pull air out on a thermostat.
Unvented attics
Spray foam or rigid insulation goes against the underside of the deck and the attic becomes part of the conditioned space. It is popular when ductwork or an air handler sits in the attic, which is typical in Georgia, because it keeps that equipment out of extreme summer attic heat. It has its own code requirements and is a design decision, not a patch for a poorly vented attic.
The rule that ties it together
Use one type of exhaust per attic and pair it with enough intake. Mixing exhaust types, such as a ridge vent with box vents or a power fan, lets them short-circuit each other so the eaves get no airflow. See roof ventilation basics and ridge vent vs box vents.