If you had to draw a picture of a house, most likely you'd draw the roof with two sloping sides that meet at the top of the roof to form a triangle. The triangles at the front and back of the house (or on the sides of the house) are called the gable ends of the house. Older homes have gable vents on either end of the attic to move fresh air from outside to replace warm, moist air inside.
Where is the warm, moist air coming from?
Only recently have we focused on making our houses more airtight to lower the cost of heating and cooling our homes. In older homes and to a lesser degree, new houses, a lot of still have warm air rising into the attic. That air has more moisture that outside air from showers, cooking and everyone in the house breathing. Yes, with every breath we exhale warm, moist air.
While basic houses typically have 2 gable ends, it's also quite common for houses to have 3 or more gables. They can be placed on any exterior wall, including attic dormers and cuploas (see below).
The Role of Gable Vents
Warm rises and whether the attic is conditioned (heated/cooled) or unfinished, the role of gable vents is one of ventilation. The goal is to replace the warm, moist air in the attic with cool, fresh air from outside. In older houses this involved the wind blowing air into one of the gable vents, and having the fresh air push the indoor air out the other gable vent(s). Of course this depended on the wind, and making sure nothing blocked the air flow in the attic.
Today's building codes require ridge vents at the top of peak of the roof, where the same warm, moist air can exit the attic. Soffit vents are found just below the roof deck, to provide the fresh air used to replace the inside air. Where soffit vents used to supply fresh air that exited gable vents, ridge vents have become the primary exit for attic air. Some people feel you should therefore close off the gable vents, while others including FineHomebuilding.com (click for more information) feels this isn't necessary.
Decisions to Make When Buying Gable Vents
Because the gable ends of a house are fairly large, many new homes include gable vents if only for decorative purposes. They come in many shapes and sizes to fit the personality of your home. When you're replacing an existing gable vent, you should try to match the shape and size, to avoid the cost of modifying the opening and siding that surrounds the vent (check Amazon for gable vents from manufacturers like Ekena).
The big decision when buying a gable vent is … not the color, but which material. It's not easy to scrape and paint gable vents due to their location … making it a common handyman repair job. That's why you want to serious consider one of the alternative materials that won't rot – metal, copper, aluminum, steel, vinyl or PVC. This is one product that makes sense to buy online because local building supply houses may not carry the size and material you want, and if you need a custom size, a company like CustomGableVents.com can build to your specs.