What is an attic fan, and how much do attic fans cost?
The types
- Roof-mounted fan: sits in a hole cut near the ridge under a low dome, wired to a thermostat and sometimes a humidistat.
- Gable-mounted fan: mounts behind an existing gable vent and pulls air out through it, with no new roof penetration.
- Solar attic fan: runs off its own panel with no wiring, only while the sun is out, which is also when attic heat peaks.
- Whole-house fan: installed in a ceiling of the living space, it pulls outside air in through open windows and pushes it out through the attic vents. It needs a large amount of attic vent area to work.
What drives the cost
The fan, its thermostat, a roof penetration with flashing or a gable mount, an electrical circuit and possibly a permit, plus any intake vents that have to be added so the fan does not starve. Ask for quotes that list each piece. Operating cost depends on motor size and how many hours it runs through a Georgia summer.
Do you need one?
Often not. A well balanced soffit and ridge vent system moves a lot of air with no electricity and nothing to wear out. Fans help most where passive exhaust is hard to install, such as hip roofs with very short ridges. They can hurt when intake is too small, because they pull cooled air out of the house through ceiling gaps, and when they share an attic with a ridge vent, since they suck air in through the ridge instead of from the eaves. See roof ventilation basics and attic heat and shingles.