Should You Install an Attic Fan?
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No, you should never install an attic fan for any reason, under any circumstance.
Whenever I lower myself out of the 150 degree attic, drenched in sweat, most home buyers and Realtors ask me if they need an attic fan. Although, an attic fan may keep me cooler, it isn’t going to do anything to help homeowners.
Why do you need adequate attic ventilation?
The benefits of attic ventilation depend on what season you are in. In the winter, your roof, the sheathing, the rafters or trusses, and the nails protruding through the sheathing are going to be cold.
Warm air and vapor from your HVAC system, showers, cooking, and even breathing are going to rise into the attic. If attic ventilation wasn’t present, the warm moist air would condense on the cold roof components. Over time this will cause your sheathing to become moldy and decayed.
Poor attic ventilation in the summer causes the heat to accumulate in the attic which gets me drenched in minutes, but more importantly reduces the life of your roof. Many roof manufacturers will reduce your warranty length if your attic is poorly ventilated. The heat in your attic will also radiate into your home and raise your cooling bills.
So why not install an attic fan?
If you don’t have adequate ventilation in your attic, and you install an attic fan, where do you suppose the air is going to come from? Some air will be pulled from the gable vents, but attic fans pull air from any leak in the ceiling.
This includes around recess lights, duct registers, your attic hatch, plumbing vents, bathroom fans, and other other opening. The attic will be cooler, but it’s from the conditioned air that you are pulling from inside the house. The problem is compounded when the gable vents are dirty, when the soffit vents are clogged, or when there isn’t any soffit ventilation. This is going to raise your the price to cool your home.
Attic fans can also create a negative pressure in the home which can cause your gas appliances to back draft, spilling CO into your home, or moist moldy air to be drawn into the home.
What is the alternative to installing an attic fan?
We recommend hiring an energy professional who specializes in recognizing the deficiencies in your attic insulation and ventilation systems. Sealing your ceiling, upgrading your insulation, and improving your ventilation are more expensive upfront, but help you save money on your heating and cooling bills, prevent moisture and mold problems in the attic, and help prolong the life of your roof.