Installing Gable Vents

By Mark J. Donovan

March 18, 2015 4 min read

Maintaining your attic at an ambient temperature is crucial for keeping down your home energy costs. Installing gable vents in your attic can help significantly in keeping your attic cooler during the summer months and provide value during winter months as well.

An extremely hot attic, caused by inadequate attic ventilation, makes your air conditioning system work much harder to keep the upper stories of your home cool and comfortable. That extra effort translates into higher energy bills. Also, an overheated attic can dramatically shorten the life of asphalt shingles, eventually leading to roof leaks and water damage to your home.

In the cold winter months, gable vents, working in concert with soffit vents, help to draw out warm moist air that may work its way up into your attic from the finished lower levels of the home. By ensuring the attic stays at an ambient outside temperature, the risk of ice dams forming on the roof eaves is significantly mitigated. Ice dams form when warm moist air gets trapped in the attic. This heats up the roof sheathing and causes the snow that is in direct contact with the roof shingles to melt. When it does, it runs down to the roof eaves, where it then freezes. Over time, this melting and refreezing cycle creates ice dams that can lead to water damage and harm the roof shingles.

Warm moist air trapped in an attic, due to the lack of gable vents or ridge vents, can also lead to mold and mildew growth, which is both detrimental to the home and to the health of its occupants. As the warm moist air rises and comes in contact with the cooler temperature roof sheathing and roof rafters, it will condense and form small water droplets that stay attached to the wood lumber. These water droplets can, and often do, act as miniature petri dishes for growing mold.

Gable vents, as the name implies, are located on the gable ends of a home, typically located near the peak of the roof. In some cases, they are the sole attic vents. This is a mistake. Soffit vents also are necessary to help draw cool air into the attic, and the gable vents or ridge vents are used to expel the rising warm air.

*Gable Vent Types

Gable vents are an alternative to installing ridge vents. Ridge vents run along the entire peak of a roof line. Gable vents serve a similar purpose as the ridge vents, but are more aesthetically pleasing. Gable vents come in a variety of shapes, styles and sizes and are constructed out of various materials including; wood, vinyl or metal. The most common gable vent shapes are rectangular or octagon. They have a series of slats, or louvers, on them to prevent rain, snow and wind from entering into the attic. They also typically have a screen attached to prevent insects, bats and other rodents from entering the attic.

Some more sophisticated gable vents include fans that help to expel the hot air out of the attic and to draw cool air in via the soffit vents. Alternatively, one gable vent on one side of the house may have a fan to draw outside air into the attic, and the gable vent on the opposite side of the home may have a fan to expel air.

*Gable Vent Installation

Gable vents typically are installed during the construction of the home. However, they can also be retrofitted if additional attic venting is deemed necessary. To install gable vents into an existing gable wall, a 2-by-4-inch or 2-by-6 frame has to be installed in the attic to support the gable vent. Then the house sheathing and siding needs to be cut out to slide the gable vent into the frame. It is then nailed into place and the exterior house siding patched. An exterior-grade caulk should then be used around the outside perimeter of the gable vent.

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