Do I need an attic fan if I have a ridge vent?
Why the fan does not help
A ridge vent works by letting hot air escape along the whole peak while fresh air enters at the eaves. A fan creates suction at one point, and the easiest replacement air is the ridge vent right next to it. The fan ends up recirculating outside air through the top of the attic while the lower attic, where moisture tends to collect, sees less flow.
If your attic is still hot
- Check intake. Look for daylight at the eaves from inside the attic. Insulation stuffed into the soffits is the most common problem.
- Count the vents. Compare intake and exhaust area to the code minimum for your attic size.
- Look at the ceiling. Upstairs rooms that stay hot are usually an insulation and air sealing issue, not a vent issue. Georgia attics will always be hot in summer; the goal is keeping that heat out of the house.
- Look at the ducts. Leaky or poorly insulated ducts in the attic can make it seem like the attic is the problem.
If your attic is damp
Find the source. Bath fans dumping into the attic, disconnected ducts, and air leaks around the hatch are the usual culprits. A fan will not cure a moisture source, and it can pull more humid air up from the house.
The rare exception
On a roof where the ridge is too short to supply enough exhaust, some homeowners choose a fan instead of a ridge vent, not in addition to it. See ridge vent vs box vents and attic heat and shingles.