How to properly ventilate your attic

Most of us think of our attics as simply a place to store unused belongings. But there are important things to consider about this space when it comes to ventilation, because it can (and will) affect the durability of your roof.

A well-ventilated attic keeps the house cooler in the summer months and prevents moist air build-up in the winter. In your attic, air enters through the intake vents (toward the bottom of the space) and flows out through the exhaust vents (at the top of the roof). Most people don’t know this, but your actual living space is insulated at the attic floor. This means that a properly ventilated attic won’t push down cold or hot air into your home. It’s just doing its job of keeping your roof healthy.

Why is proper ventilation so important? Let’s consider your home in the winter months. The air that flows upward is warm and moist, and if it lingers in the attic area, it will condense on the underside of the roof sheathing and cause rotting. In the summertime, good ventilation will lead to lower utility bills because the hot air will move out of the attic and remove moisture. And if you have shingles, ventilation will help them last longer.

There are several different types of vents available for your roof. The most common include:

• Whirlybird vent: Also called “turbine vents,” these semi-mechanical units are used to help remove heat from the cavity of the ceiling.
• Static vent: These individual vents are installed near the ridge of your roof.
• Ridge vent: This type of nonpowered ventilator that isn’t very noticeable, because it tends to blend in with the rest of the roof. It provides uniform cooling along the deck of the roof. from end to end. Ridge vents are especially beneficial on certain types of roofs, such as those with cathedral ceilings. They are less effective on hip roofs.
• Gable vent: This is normally the triangular-shaped space on your attic wall at the point where your rooftop meets. It can also be square, octagon or round.
• Soffit vent: Located under the eave of the roof — making it an intake — this type of vent should never be covered up with insulation, because it can no longer help maintain airflow in those circumstances.

Each one of these types of vents is designed to handle air flow in its own way. For this reason, combining different types of exhaust vents is never a good idea, because it will decrease the efficiency of the ventilation, which leads to higher utility bills. If, for example, you have a whirlybird vent (which draws air out) as well as a static vent (which relies on the intake to force the air out), your system can short-circuit and cause unwanted moisture to develop.

Then there’s the issue of over-ventilating. Sometimes, roofers will miscalculate the number of vents required, or they will add more vents upon request by the homeowner. This could lead to issues with airflow in your attic. It’s also very important to keep your ventilation system balanced. Never allow the amount of exhaust ventilation (the kind at the top) exceed the amount of intake ventilation.