Ridge Vent vs. Attic Fan: Major Differences
Roof ridge vents and attic fans both promote airflow in attics. Unlike attic fans, ridge vents are passive, not mechanical, ventilation devices. Also, ridge vents move air both in and out of an attic; attic fans mostly move air outward, from the attic’s interior to the outdoors.
Ridge Vent
A ridge vent is a plastic or metal vent that runs the entire ridge of a roof to allow airflow. After a slot is cut on both sides of the ridge, the ridge vent is installed over the top of the slot to protect the attic from debris, rain, and snow. Next, cap shingles are often installed over the ridge vent for better appearance. Some ridge vents do not need cap shingles. Since heat rises, ridge vents let attic heat escape where it matters the most: the very top. Though the ridge vent’s profile is low, its venting capacity is great because it runs the length of the house. Wind reaching the house from either direction can flow into the attic, though to a limited degree. Ridge vents are passive cooling systems; that is, they do not require electricity or any other power to move the air.
Attic Fan
An attic fan can be located either vertically on the home’s gable or on the roof. When the fan is on the gable, the fan mechanism is entirely in the attic. When it’s on the roof, it’s located high on the roof, less than 24 inches from the ridge. Part of the fan is on the roof and part is located inside the attic. In automatic models, when a thermostat in the attic senses that the temperature has reached a set point, it triggers the electrically operated attic fan to turn on and move the hot air from the attic. Since fresh air must replenish the removed air, any attic fan installation must also have a passive air intake in the eaves, soffit, or fascia. Ridge vent material comes in coils that are unrolled along the length of the slot. Ridge vents are often finished off with cap shingles that match the roof shingles. Cap shingles are left open on the side to keep the vents exposed.
Attic Fan
An attic fan can be installed relatively easily in a house’s gable. If the fan is roof-mounted, it is a bit more difficult to integrate the fan with the existing shingles and protect against leaks. With both types of attic fans, power is always necessary. So, unless there is already a dedicated circuit in the attic, an electrician will need to create a circuit and extend it to the attic.
Appearance
Ridge Vent
Ridge vents blend in well with the roofline. Even with added shingles, ridge vents are barely more than 1 inch high. Since they follow the roof ridge, they are not usually visible.
Attic Fan
Roof-mounted attic fans are visible and can be obtrusive, especially if more than one is installed. Gable-mounted attic fans are less visible, except when you happen to be looking at the roof from the direction of that gable.
Cost to Operate
Ridge Vent
Being passive venting devices, ridge vents are openings in your roof; they do not move. No motors are needed for operation. While ridge vents do occasionally need to be cleared of debris, there is no cost to operate them and little cost to maintain them.
Attic Fan
Attic fans have motors and are electrically powered. The cost of operation depends on the climate, size of the house, and the number of attic fans installed. Most attic fans run off of 120V power. A 2,860 cubic foot per minute (CFM) attic fan can draw as little as 157 watts. So, while attic fans do require electricity, the power draw is low and operation is only intermittent.
Which Should You Buy?
Attic ventilation of some type is required by most building codes. Ridge vents and attic fans can work in conjunction with each other. In this scenario, the ridge vent passively handles ventilation and cooling duties until it reaches its full capacity. Then, the attic fan takes over. If you had to choose just one—and your attic has a great need for ventilation—an attic fan is your best bet. Attic fans in the $300 to $400 range can move upwards of 5,000 CFM. For lower capacity ventilation at a steep cost savings, a ridge vent might be your best choice. Sixty feet of plastic ridge vent costs $100 to $200.
