Attic ventilation might seem like a minor consideration, but when properly installed, it can extend the life of your attic and roof structure – saving you hundreds of dollars in repair costs.
During warmer months, ventilation helps keep attics cool. It helps prevent hot, moist summer air from warping the roof sheathing. It also stops shingles from deteriorating prematurely. What’s more, fresh air in the attic makes a home much easier to cool, which can result in lower energy costs.
In winter months, ventilation helps reduce moisture to keep attics dry. It stops water from backing up under shingles, damaging insulation, and rotting the roof structure itself. It also helps prevent ice dams from forming. Ice dams occur in areas where snowfall and cold temperatures are common and pose a special problem because they prevent melt water from running off the roof. They can even cause leaks inside your home, resulting in drywall damage.
What is attic ventilation?
Intake and Exhaust
“Ventilate” comes from the Latin word for “to fan.” Simply put, it’s the action of moving air. Out with the hot. In with the cool. And that’s exactly how ventilation works. It provides conditions that allow air to flow. Every time stale, overheated air in your home or attic is vented out and fresh air is pulled in to replace it, you have what is known as an “air exchange.” But ventilation is much more than a simple breeze blowing through your house. It’s a process that provides a steady, high volume of air movement. Think about it as a system of components, all sized and positioned to provide constant intake and exhaust of air.
According to most building codes, you need one square foot of vent area for each 150 square feet of attic floor space. The minimum is one square foot for every 300 square feet of attic floor space if there is a vapor retarder or the space is balanced between the ridge and intake vents. A balanced ventilation system means about 50 percent of the required ventilating area should be provided by exhaust vents in the upper portion of your attic with the remaining 50 percent provided by intake vents.