Should You Install an Attic Exhaust Fan?


attic ventilation fan

House air leaks into the attic. An attic fan will pull air in from the house even faster

Summer is a few weeks away, but as far as  I am concerned, summer has unofficially started in Richmond. Inspecting in the baking attics of Richmond is my second least enjoyed part of my job. Someone needs to do it though. What I have learned overtime is that 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 exhaust fan.  Although, an attic fan may keep me cooler, it isn’t going to do anything to help homeowners. 

I repeat. Attic Exhaust fans will not help you


Will an attic fan cool down your attic?

Probably! But not because its increasing the ventilation in your attic. It will cool down your attic because its going to work had at pulling the air conditioned air from in your house, through your ceiling, and into your attic. This will increase your utility bills, and make me happy while inspecting, but it is not going to do you any favors.

Why do you need adequate attic ventilation?

attic fans suckThe 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. 

How to Cool Down Your Attic Without 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.

If you want to make some upgrades yourself, get some Great Stuff Insulation Spray Foam, and seal any openings between your ceiling and attic like in the image above where air is leaking into attic. A ton of energy loss occurs at the attic hatch, so buy and install an Attic Hatch Insulation Cover. You can even get a Free Blown Insulation Machine Rental when you buy insulation at lowes. If you blow in your insulation, don’t forget about this potential fire hazard.

How to Install an Attic Fan?

Don’t Do it!