How to Install an Electric Gable Vent

Select the location for your vent. Mark a square the size of the vent on the inside of the roof gable. Drive nails through the corners of the square all the way through the wall sheathing and the exterior siding.

Place a ladder against the gable in easy reach of the proposed vent. Climb up and mark the outline of the vent on the wall by linking the four corners together. Set your circular saw blade as deep as it will go and cut out the square. Knock it out into the attic with a hammer.

Caulk around the back of the vent frame flange, or rim, with 100 percent silicone caulking. Set the vent into the hole and screw the vent in place with treated deck screws through the vent's installation flange into the siding of the house. Slip the trim ring over the outside of the vent and snap into place by tapping with a rubber mallet.

Measure between the closest studs on either side of the vent inside the attic and cut two pieces of 2-by-4 to fit snugly between the studs horizontally, one at the top and one at the bottom of the vent. Tap them into position and nail through the studs in the ends of the 2-by-4 pieces.

Run the needed wire to the location of the vent. Hire an electrician to make the connection to your breaker box to avoid problems with building and fire codes. Set the control box for the fan's thermostat against a stud on one side of the vent opening. Drive at least two 1 5/8-inch treated deck screws through the back of the junction box that houses the control into the stud beside the vent.

Make certain that the breaker connected to the power line of the fan control is turned off. Pull the needed wires into the control box and connect to the fan's power leads according to the manufacturer's instructions, which are included with the fan.

Attach the fan to the two horizontal 2-by-4 braces you installed. Use the fan as a template to mark screw holes in the 2-by-4s. Bore 1/8-inch pilot holes where each of the screw holes of the fan frame meet the 2-by-4s. Set the fan in position and drive 3/16-by-1-inch lag bolts into each hole with a rubber washer on each to dampen vibration. Tighten them with a socket wrench.

Turn the breaker back on. Set the thermostat to the temperature at which you would like the fan to start running.