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How Your Attic Ventilation Could Be Ruining Your Home

20 September 2013

The main purposes of attic ventilation are to provide comfort to your home, help protect against damage to materials and the structure of your home and to help reduce energy consumption during all four seasons here in the Midwest. During the warmer months, ventilation helps keep your attic cool and in the winter months, it reduces moisture keeping your attic dry and preventing ice dams. Proper attic ventilation in your home allows the flow of outside air through your attic, protecting your efficiency of the insulation and helps lower the temps in your living space. The U.S. Federal Housing Administration recommends a minimum of at least 1 square foot of attic ventilation for every 300 square feet of attic space. This amount should be divided equally between intake and exhaust ventilation allowing proper air flow.

What Damage Can Happen with Improper Ventilation?

  • Damage to your siding,  interior paint and wallpaper
  • Warping, cracking or breaking down of wood framing
  • Premature aging of your roofing system
  • Roof deck warping & rooting
  • Mildew & mold growth
  • Buckling of shingles and felt

In the winter, when using household appliances such as your shower, bathtub or cooking ranges can contribute to excess moisture build-up which will allow moisture to condense and fall, soaking your insulation putting you at risk for mold. In the winter, ice and snow on your roof will melt and run down the deck to the cooler eaves of your roof. This runoff can re-freeze, creating what is called an ice dam that can force water to back up under your shingles, causing water to leak into your home. If you roof is properly ventilated, it will reduce the amount of melting that occurs, therefore reducing ice dams that could form.

Balanced Systems Will Provide Optimal Air Flow

A properly designed ventilation system requires balance and that balance is achieved in two ways airflow & intake.

  • Airflow capacity must be balanced between intake and exhaust vents. Half of the vent area must be high in the attic, with the other half lower in the attic. Without this balance the area of effective ventilation is limited to the lesser of the two vent areas. If 75% of your venting is high and only 25% low, the ventilation is limited to the air moving through the lower vents.
  • The vents that are placed high must act as exhaust vents, while the low vents act as intake vents. That placement will assure continuous air flow moving the right direction.

Different Types of Vents

Ridge Vents – these are the most economical and effective kind of attic vents. They run the entire length of the roof peak and are typically covered with shingles so they blend into the roofline. These types of vents work effectively all year round and ventilate your space evenly providing a large volume of air flow.

Soffit Vents – are most commonly used in tandem with ridge vents. They can be installed above or below your gutter system. These types of vents keep your attic dry in the winter and cooler in the summer.

Gable Vents – are installed on the exterior attic walls providing air circulation during extreme temperatures and humidity. These types of vents are designed to add interesting accents to the exterior of you home. They come in a variety of shapes and are covered with a mesh screen backing that keeps out insects.

Turbine Vents – are wind-driven that are installed along the face of the roof. When the wind blows, the turbine spins and draws air from your attic. These vents can remove large quantities of humid air at a time. These are often used in conjunction with soffit venting systems to allow adequate air circulation.