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The Home Depot

How to Install an Attic Fan

Pro Referral > Home Guides > Attic > How to Install an Attic Fan
How to Install an Attic Fan

A powered fan can improve air circulation and moisture control in your home’s attic, helping reduce heat in the hot summer months and prevent moisture damage and mold growth all year. Bringing down attic temperatures and reducing humidity can prolong the life of roofing materials, minimize the potential for moisture problems, and increase cooling efficiency.

Materials Skill Level Estimated Time
• Fan Intermediate 2 to 4 hours
• Tape Measure
• Hammer
• Razor Knife
• Flat Bar
• Ladder
• Lumber
• Reciprocating Saw
• Screwdriver or Drill

There are several common options available among attic fans, so when choosing yours, keep a few important details in mind. The first is a power source. If you do not have an electrical supply in the attic that you can connect to easily you will need to hire an electrician to run appropriate wiring for the job or select a solar-powered fan that does not require an electrical connection. Next, determine the best location for your fan, the roof or a gable wall, and choose a model designed for that application. Finally, be sure to choose a fan with the capacity to move the correct volume of air in your attic, which is generally measured in cubic feet per minute (cfm). The documentation for most fans includes a table to help you calculate the volume of your attic and also indicates the size range of an attic (in square feet) that they are appropriate for and what eave and soffit ventilation is required for adequate air intake.


With a fan and mounting location selected, you can get started with the project. Most attic fan installations require basic tools, such as a tape measure, hammer, screwdriver or drill, razor knife, flat bar, and reciprocating saw. You may also need some lumber or supplies to mount and cover a gable-end fan, and remember that the installation will require working both in the attic and on the roof or a ladder, so take appropriate safety precautions.


Installation Process

Follow the steps below to install your attic fan.

  1. 1. Measure the Hole for the Vent

    If there is not already an opening for an existing gable or roof vent, cut one for your fan according to the manufacturer’s specifications. First, mark the center of the opening between the rafters inside and drill a pilot hole through to the outside. In order to avoid damaging the shingles or siding, move to the outside to make your cut.

  2. 2. Cut the Hole for the Vent

    Locate your pilot hole and, using a tape measure or string as a compass or the manufacturer’s template, mark the outside of the hole with a pencil or chalk. Use a reciprocating saw to cut out the siding or roofing and sheathing beneath. On an asphalt shingle roof, you may also remove the shingles in the area of the pilot hole entirely, then trim them to fit and reinstall them once the fan is in place. For a gable wall fan, it may also be necessary to remove or cut back the siding to provide a mounting surface for an exterior vent.

  3. 3. Prepare the Surface for the Fan

    To mount the attic fan from the roof, slip the nailing flange of the fan under the shingles above and around the opening and slide it into place. If there are roofing nails blocking the path of the flange, carefully remove them with a small flat bar.

  4. 4. Mount the Fan

    Gently lift the top layer of shingles and secure the flange to the roof deck with roofing nails across the top and on the side. Do not nail the exposed lower half of the flange unless specified by the manufacturer, and apply roofing cement as directed. If you removed the shingles earlier, simply nail the flange in place and replace the shingles after trimming them to fit.

  5. 5. Mount the Fan to a Pre-Existing Vent

    The steps needed to mount a gable-end fan will depend on the condition of the site. If there is already a static vent in place and you did not need to cut an opening, you may need to construct a mounting brace out of 2x4s or use plywood to create a frame or nailing flange you can use to mount the fan to the existing framing. Check the installation specifications for the method that is relevant to your application and use the mounting brackets provided with your fan to attach it to the framing or brace as directed. If there is not a static vent in place that will serve as a vent for the new fan, install an appropriate louvered vent from the outside.

  6. 6. Connect Electrical Wires to the Fan

    If your fan requires a wired connection, follow the manufacturer’s instructions for correct placement of the thermostat and/or humidistat, adjusting their settings, and connecting to your home’s power supply. Be sure to turn off the power to the entire circuit before working with any wiring and test the fan to be sure it spins freely before connecting the power. If you are not experienced and comfortable working with electricity, an electrician can make these connections for you.

  7. 7. Non-Electrical Fans

    If your fan is solar-powered and requires the installation of a remote panel, find a suitable location on the roof; typically southern or western exposure with minimal shade. Drill a hole through the roof to run the supply wire to the fan inside, or run the wire along the roof and wall and through the gable vent, securing it as directed by the manufacturer. Mount the panel over the hole (if applicable) by nailing it in place under the top layer of shingles at the top of its flange and seal with roof cement if required.

Level of Difficulty

Installing an attic fan is a project of moderate difficulty for most homeowners, but one that can have a significant impact on cooling and maintenance costs. Be sure to choose a fan that is well suited for your application and follow all the manufacturer’s guidelines for the installation and you should have many years of trouble free operation.

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