What is the Purpose of Roof Vents?

Published on Tuesday August 6, 2024

Ventilation is the flow of air through a system of intake and exhaust. It plays an important role in extending the life of your roof, reduces energy costs, and eliminates indoor temperature extremes.

Let’s take a more in-depth look at how ventilation works for your home.

How do roof vents work?

Ventilation only works when air flows. Proper roof ventilation in your attic allows air to flow through it, preventing it from becoming overheated and causing moisture.

There are two primary methods for creating airflow within an attic:

Mechanical. Requires a power source.
Natural. Whenever possible, natural roof ventilation is used. The stack effect and the wind effect work together to naturally circulate air.
- Stack Effect: Occurs when hot air rises and creates a higher pressure at high points in the attic. Hot air that escapes is known as exhaust. However, this hot air cannot escape without an inlet for cooler, low-pressure air. The cool air that enters is referred to as “intake.”
- Wind Effect: When the wind blows against the outside of a roof and increases the volume of intake and exhaust. Intake and exhaust generate the natural flow of air to create a well-vented attic.

This video further explains how roof ventilation works:

Roof ventilation at work

Roof ventilation systems are unique to every home. Factors such as code requirements, regional climate, and roof and ceiling designs all need to be considered when venting your roof.

There are two main types of roof ventilation:

Exhaust vents

Ridge vents are the most common type of exhaust vents. They’re installed at the intersection of two roof planes known as ridges. They’re typically made of molded, high-impact copolymer and installed underneath a final layer of shingles to give the roof a seamless look. To the untrained eye, ridge vents can be almost invisible.

Roof louvers, gable louvers, wind turbines, and power attic ventilators are all visible exhaust vents mounted on the outside of your roof. Like ridge vents, roof louvers and gable louvers work without electricity.

Wind turbines can also work without a power source, but they’re most effective when there is a constant source of wind and aren’t as effective as ridge vents.

Power attic ventilators, which run on a power source, are an exhaust vent option for specific roof designs or areas without much wind.

Intake vents

Like ridge vents, edge vents are made of copolymer material. Located at the edges of the roof, these intake vents can be installed at the eaves under the soffit, at the drip edge, or under the shingles at the roof’s edge. The intake vents work with ridge vents to allow cool air to enter the attic space, forcing warm air to exit through the ridge vents.

3 benefits of roof ventilation

Roof vents prevent damage to your shingles. They also provide the following benefits:

Extends the life of your roof

Ice damming happens when heat from inside your attic combines with heat from the sun to melt snow and ice on your warm roof. When the resulting water runs to the edge of the roof, it begins to refreeze. As the ice and water build up at the edges of your roof, it can back up behind/underneath the roofing materials, causing damage to your whole roof system, your attic, and even inside the walls of your home.

Proper ventilation helps this warm air escape before it has a chance to melt the snow and ice on your roof. A well-ventilated roof is easy to see in the winter months. It still has snow on it, but not an icicle in sight.

This video shows how a well-vented roof protects your roof from ice damming:

Ventilation also benefits a roof when it’s hot outside. When the temperature outside rises, the temperature on your roof can be nearly double. A hot roof over a poorly vented attic translates into a sweltering attic.

Unventilated or poorly ventilated attics don’t have an escape route for the heat that builds up. This buildup of heat can damage your shingles from the inside out.

An evenly vented roof will allow the hot air to escape, keeping your roof and attic cooler.

Reduces energy costs

When the temperature increases outside, a properly vented roof allows heat to escape, thereby reducing the workload on your air conditioner. An air conditioner that’s running less means a lower electric bill.

Reduces indoor temperature extremes

Poorly vented roofs often cause indoor temperature extremes. Once your roof is adequately vented to allow hot air to escape and cool air to enter the attic space, your home will be more comfortable year-round.

How many roof vents do you need?

The rule of thumb is one vent for every 300 square feet if there is a vapor barrier in the attic. If there is no vapor barrier, it’s recommended to have one for every 150 square feet. However, a professional roofer can give you a more accurate estimate.

Improve Your Roof Venting With Long Home

Long Roofing utilizes the best roof ventilation techniques available. Accredited by the Asphalt Roofing Manufacturers Association, a CertainTeed roof ventilation system will ensure that you enjoy the advantages of a well-ventilated roof for 50 years or more when installed as part of a whole roof system by Long Home.

Contact our roofing team for more information and a free estimate!