For many homeowners, the concept of putting insulation in the attic in order to keep the home warm and then intentionally allowing cold air to enter into the attic by installing ventilation seems counterproductive. However, having the proper mix of insulation and ventilation is essential for keeping the home at the right temperature, protecting the roof, and increasing the energy efficiency of the home.
One of the reasons that having proper ventilation is key to protecting the roof is because during the winter months, the heat from the interior of the home collects in the attic. This heat in turn warms up the peak of the roof. Any snow that is collected along the peak of the roof begins to melt. As the melted snow travels down the side of the roof, it begins to come in contact with the parts of the roof that are cooler. Eventually it begins to refreeze, forming a ridge of ice. As this process continues throughout the winter, the ridge of ice get thicker and heavier and will eventually cause icicles to form along the edge of the roof. This phenomenon is known as an ice dam.
Ice dams are dangerous because they create a ridge where melted snow can accumulate. Eventually, the water will find its way underneath the shingles, penetrate the underlayment, and filter into the home. However, if a house is equipped with adequate ventilation, the heat that accumulates at the peak of the roof during the winter will escape through the vents. This will keep the entire roof at a safe and even temperature.
Proper ventilation will also ensure that condensation does not build up in the attic. If condensation builds up in the attic, it will effect the R value of the insulation, making it less effective. Additionally, improper ventilation will cause the temperature in the attic to rise to a point that it will negatively affect the composite shingles that are used as a roofing material. In fact, attic heat can get so hot that it can cause the adhesive that sticks the shingles to the roof to deteriorate. Eventually, the shingles will fall off the roof, leaving the roof with spots that are vulnerable for water penetration.
If a homeowner is concerned about whether or not their roof has sufficient ventilation, it would be a good idea for them to speak to professionals and get details now so that they can make the needed adjustments. A roof that is properly ventilated will lead to a home that is energy efficient, comfortable, and well protected from the elements.