Homeowners may not think much about how summer heat impacts their roof, but just like you can get overheated if you stay out in the heat too long, your roof can overheat, too.
What is a roof vent? A roof ventilation system pulls cool air inside to circulate fresh air through the attic space, effectively cooling down your home. This regulates interior temperatures and keeps energy bills down.
Although you may know what a roof vent system is and what it does, exactly how does it work? Read on to learn how this roofing ventilation system works to keep your attic from overheating.
What is a Roof Vent?
Think of roof vents as the device that allows your roof to breathe. A roof ventilation system is an essential part of your roof that allows outdoor air to pass in and out of slots in your attic.
To make sure things don’t get too hot and humid upstairs, roof vents control the flow of air by bringing fresh air into the attic and pushing out hot air. In summer, the attic airflow protects your attic from overheating. In the winter, vents help prevent ice dams and moisture buildup.
You might not think a lot of condensation can get trapped in your attic space, but there is a lot of moisture in your home that drifts upward into the attic, generated from activities such as cooking, showering, or doing laundry.
A roof vent:
- Prevents temperature extremes inside your home
- Reduces energy costs
- Extends the life of your roof
Parts of a Roof Vent
Intake and Exhaust Vents
Naturally, the most critical component of an attic ventilation system is the roof vents themselves. Roof vents are either intake vents, which pull air into the attic space, or exhaust vents, which push stale, old air out of the attic and back outside.
Intake vents bring cool air into your roof, like your roof inhaling a gulp of fresh air. For this reason, intake vents are usually installed at the bottom of the roof.
Exhaust vents exhale air by pushing hot air out of your attic. Exhaust vents are located high on your roof, generally close to the roof ridge.
Baffle
Baffles are part of the roof’s vent system. A baffle is a small chute that channels airflow into the attic. Baffles are sometimes called insulation stops or rafter vents.
Baffles can be made from several different materials:
- Cardboard
- Metal
- Plastic
- Plywood
- Rigid foam
- Styrofoam
- Wood
Baffles are not the same as insulation. Rather, they are located between the insulation and the outside roof vent, channeling air from the outside to the attic interior. Without baffles, attic insulation would block air from flowing into the attic and stop proper circulation.
Roof Vent Caps
Roof vent caps offer protection for your home by keeping debris outside where it belongs. They block rain, snow, and hail from falling into your attic.
Roof vents are slits in your roof that allow air to pass through, but sometimes wind isn’t the only thing that gets in. Animals seeking shelter might find their way into your attic. But roof vent caps act as a barrier that will prevent wildlife from getting into your attic.
Attic Fan
Attic fans perform essentially the same function as roof vents: They keep your home from overheating and prevent moisture buildup in your attic space.
Like any other kind of fan, attic fans are designed to cool things down by pulling hot air out of the attic. Fans work as both intake and exhaust vents; they depend on electricity and solar power to operate.
Like an AC unit, attic fans are controlled by a thermostat and turn on to keep the attic at the desired temperature. Without proper ventilation, attics can reach up to 160 degrees Fahrenheit during the summer months.
Although effective, attic fans aren’t enough to ventilate an attic on their own. You will need a combination of attic fans and roof vents for a proper ventilation system.
Soffits
Soffits are the long wooden board running underneath a roof’s overhang. If your roof doesn’t have any overhang, it doesn’t have soffits.
Soffits are where soffit vents are installed, making them an important part of the ventilation system. Although they are usually made of wood, soffits also can be made from vinyl and aluminum.
How Does a Roof Vent Work?
The primary purpose of roof vents is to protect your roof from heat and moisture. Roof vents are powered in different ways depending on the type. Some use electric power, others use wind power.
Passive vents don’t have a power source at all but rather rely on external forces to circulate air inside your attic. Active vents use electricity or solar energy to work.
Hot or moist air that would normally stay trapped in your roof is circulated and expelled by vents. The stack effect and the wind effect both work in tandem to circulate air and provide your roof with an efficient ventilation system.
Stack Effect
The stack effect has to do with the way air flows in and out of a building. Hot air naturally rises because it is lighter than cold air. Conversely, cooler air is denser and stays at a lower level.
As hot air rises, it creates pressure lower in your attic in an effect known as the stack effect. For good ventilation, an exhaust vent needs to be placed at the highest point on the roof where the rising hot air can escape while intake vents are needed lower down so they can push cool air into the attic.
Wind Effect
When wind blows at fast speeds, it increases the speed of air circulation flowing through your roof’s ventilation system. This is called the wind effect.
When wind hits the side of a building it exerts pressure as it moves inside. As a result, the high wind pressure seeks equilibrium and flows to fill the whole attic space by flowing toward areas where there is lower wind pressure.
Types of Roof Vents
Different types of roof vents have their pros and cons, but they all work effectively. Typically, roof vents are categorized into two groups: passive and active.
Active roof vents require an electric or solar power source for them to be able to control airflow.
Passive roof vents don’t require a power source, as they don’t actively manipulate the flow of air. Rather, passive vents rely on the wind to push air in and out of the attic.
Active Vents
Active vents need an energy source to work, whether it be electrical or solar energy. This means that active vents are going to cost money to operate, which will increase energy costs. There are many types of active vents:
- Power vents. Aptly named, power vents are a powerful force that can move large amounts of air. Shaped like an upside-down dinner dish made of tin, they are an excellent choice for homes with high humidity. When paired with a humidistat, power vents are an unstoppable force in regulating your attic’s moisture levels.
- Off-Ridge Vents. Used for 3-tab shingle roofs, off-ridge vents are a durable choice that is great for areas that experience high winds.
- Solar vents. The solar roof vent saves your attic and the environment and is powered by built-in solar panels. The downside of solar vents is that they don’t generate enough power to work all the time, so when their battery runs out of energy, they shut down to recharge.
- Ridge Vents. Ridge vents, a popular roof vent choice, form a continuous line of vents embedded along the very top of your roof, making them aesthetically pleasing and keeping them out of sight.
Passive Vents
Acting as a channel for air to flow in and out of your attic, passive vents rely on external forces to power them. They don’t have any moving parts or electrical components; instead, they allow wind and convection to do the work.
- Ridge vents without baffle. Without a baffle, ridge vents become passive vents. Otherwise they are similar to active ridge vents.
- Gable vents. To add a charming accent to the eaves of your home, gable vents beautify your house while simultaneously performing as a practical component of your home’s ventilation system. Gable vents are customizable and made of plastic, metal, vinyl, or wood.
- Turbine vents. Commonly called a “whirlybird,” wind turbines are reliant on wind to spin them for them to work. The mushroom-shaped spheres work great in windy areas.
- Soffit vents. The convenient thing about these intake vents is that they are installed under a building’s soffits, keeping them tucked out of sight and out of mind. Soffit vents are the most common type of roof vent.
- Box vents. What do flat vents, turtle vents, and louvers vents all have in common? They’re all the same roof vent. Most commonly known as box vents, these box-shaped vents are low-maintenance and a durable roof vent.
- Cupola vents. Regarded as the most beautiful roof vent, cupola vents are used as much for decoration purposes as they are for ventilation. If you see an elegant watchtower on top of a roof, you are looking at a cupola vent. The downside of cupolas is that they are expensive and high-maintenance.
- Dormer vents. Leak-resistant and wildlife-proof, dormer vents are a good choice for many types of roofing materials.
Benefits of Roof Vents
Roof vents aren’t just for show; they’re an essential component of the roofing system that protects your roof and prolongs its lifespan. There are many benefits to having proper roof ventilation:
- Extends your roof’s lifespan. Without proper ventilation, your attic turns into an oven and bakes your shingles from below. Damage from the sun can wreak havoc in your attic, as overheating can damage rafters, wood framing, attic underlayment, insulation, and shingles. It causes premature aging and shortens the life of your roof.
- Prevents mold growth. Too much moisture buildup inside your attic could lead to rot, mold, fungus, or mildew. Not only does mold growth demand repairs, it can also pose health risks to the building’s inhabitants..
- Prevents moisture buildup. Moisture and condensation will form in an attic that doesn’t have proper ventilation. Water damage can warp wooden decking and cause sagging or spongy roof decking.
- Reduces energy costs. Every homeowner wants to save as much as possible. It pays to have a good ventilation system, since ultimately a good ventilation system will save you money on energy bills.
- Thwarts ice dams. Roof vents help even out temperatures between your attic and the outdoors, which prevents ice buildup on your roof. Ice dams are usually a sign of poor ventilation and too much warm air trapped inside your roof.
- Improves indoor temperatures. If you notice some rooms have a noticeably lower or higher temperature than the rest of the house, such uneven temperatures may indicate a problem with the ventilation system.
- Stops overworking the HVAC unit. Roof vents push out hot air, which helps keep the house cool and cuts back on the need for running your air conditioner. If your HVAC unit is recently working overtime or if it breaks down, it might be under too much stress due to poor ventilation.
How to Maintain a Roof Vent
Maintenance is the key to keeping your roof vents performing. Roof vents may underperform if they are blocked or clogged by debris such as:
- Cobwebs
- Insulation
- Leaves
- Snow
- Twigs
Typically, blocked vents can be cleared by using a leaf blower or air nozzle. It’s a good idea to clean soffit vents every two years or so in order to remove any debris and dust.
Some roof vents can be knocked loose by the wind or from loose screws. Whirlybirds are especially prone to being blown askew by rough winds. If your roof vent has been knocked loose, you should get it fixed immediately, otherwise it might cause leaks.
If you’ve noticed that your roof vents are plagued with rust, they will have to be replaced to get them back in good working order. If a roof vent has moving components, rust may prevent it from moving freely and the turbines can get stuck.
Another reason a roof vent may not be working properly is if there are too few vents on your home. If a roof vent is broken or underperforming, you can call a professional and have them inspect your ventilation system. A roofer should be able to help you figure out if you need to add more vents to your roof.
Cost to Install Roof Vents
Prices for roof vents typically range from $297 to $583. Of course, how much a roof vent will cost is dependent on the type of roof vent you choose, as some styles of roof vents are more expensive than others.
| Type of Roof Vent | Typical Price Range (including labor) |
|---|---|
| Box | $53 – $197 |
| Turbine | $58 – $250 |
| Dormer | $73 – $283 |
| Power | $233 – $1,100 |
| Cupola | $163 – $837 |
| Gable | $85 – $265 |
| Ridge | $297 – $583 |
| Solar | $318 – $1,200 |
| Soffit | $297 – $413 |
How Many Roof Vents Does My House Need?
The more the merrier may be true in some cases, but that’s not necessarily the case when it comes to the number of roof vents you need for your home. A balanced combination of both intake vents and exhaust vents is necessary to keep your home cool and well-ventilated.
Too much ventilation can be harmful to your home, but so can too little. If large amounts of air pass through your attic too quickly, it causes drafts through your attic that lead to moisture buildup. Too much ventilation can cause water damage and put strain on your AC unit.
But how do you know if you need to add more vents to your home’s ventilation system? There are several signs to look for:
- Water leaks
- Water damage
- Moisture in your attic
- Mold
- Sagging roof
- Loose shingles
- Visible flashing
- Increased energy bill prices
- Frost in attic
- Ice dams
- Temperatures differences from room to room
- Hot ceiling
- Air conditioning is overworked
- Roof is hot to the touch
- Wildlife entering your house
- Rust
Typically it is recommended that for every 300 square feet of attic floor, there should be one square foot of vents.
FAQs About Roof Vents
Roof vents can cause leaks if they are:
• Improperly installed
• Knocked loose
• Rusted
• Not sealed correctly
• Damaged
Without good sealing, water can leak through the cracks. If you have poor ventilation, too much condensation can form in your attic and cause leaks.
If a roof vent is clogged by leaves or any other type of debris, it won’t be able to function properly and the attic air will grow stale. Problems such as moisture buildup or overheated attics may occur. A blocked roof vent needs to be cleared of debris so it can operate properly again.
Roof vents are sealed so rain can’t get in. As long as a roof vent is properly installed and hasn’t been blown loose by the wind, rain shouldn’t get in. However, damaged roof vents may be vulnerable to rain getting through.
When to Hire a Roofing Professional
Roof vents are a necessary element for your roofing system that protects your roof and home from damage. A good ventilation system will keep your home’s temperature more comfortable and will save on your power bills.
If your home needs more vents or if you’re getting a completely new roof, find a local roofer to install roof vents on your home.
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