The easiest place to install an attic fan is in a location where a gable or roof vent already exists, according to Lowe's. Placing a fan in one of these spots often requires making the vent bigger, but it eliminates the need to cut a new hole.
Fans mounted in a roof vent include flashing bases to prevent leaks. Shingles must be placed around the bases to keep the fan secure. Attic fans are equipped with thermostats that turn on the fans when the heat in the attic reaches a certain temperature. Some fans also include a humidistat, which turns the fan on when humidity is high in the winter.