Your roof must breathe--proper ventilation is key to its longevity. In your attic the heat, left unchecked, can shorten your roof's lifespan, and the cold can cause moisture to build up, leading to rot, which can spread to the rest of your home. Circulation takes place when fresh air comes up through your soffit, or eaves vents, and out through ridge, or gable, vents to maintain more even temperatures and a dry environment.
The gable vent has been in use for the better part of a century. Traditionally they were carpenter-built wooden vent grilles, and have since been replaced by mass-produced vinyl and metal grilles. Since the 1980s, many homes have been built with ridge vents. Ridge vents require professional installation and are best added when replacing the roof.
The ridge vent is a line of raised shingles running along the peak, or ridge, of your roof. Being at the very top gives ridge vents an advantage: The hot air in your attic naturally rises and exits through the vent and draws fresh air in behind it through the soffit vents, creating a steady flow of fresh air.
Situated near the peak of your roof in the gable wall, gable vents are basically a hole cut through the house wall with a wooden, metal or vinyl louvered vent. Some have adjustable louvers, while most are fixed. Most of the ventilation provided by gable vents comes from cross ventilation blowing directly across the attic from other gable vents, leaving the stale, hot air in the peak of the roof and the fresh air still near the ceiling joists.
Installing Gable Vents
Gable vents are simple and inexpensive to install. The hole can be cut with a household circular saw. The vent itself is a prefab unit that fits neatly into the hole and is nailed in place. Electrical fans can also be added to increase the efficiency of the vent. Thermostats are typically wired to start the fans at a set temperature.
Installing Ridge Vents
In new construction, the ridge vent adds a small amount to the cost and is simple to install. The ridge of the roof is constructed with a raised beam to nail the shingles to. Some vents are left open without any obstruction, while others are filled with a plastic wool-type filter to prevent rain water blowing back under the vent. In existing construction, this becomes more difficult and expensive. It is typically done by a roofing contractor as part of installing a new roof.
- Photo Credit air vent image by Vladimir Titov from Fotolia.com
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