The air you breathe in doesn’t just keep you alive. It affects your health, mood, and overall lifestyle. Breathing fresh air can enhance your mood, make you more energetic, help with digestion, and even improve the quality of your sleep.
Since the average human spends at least a third of their day at home, it’s important to keep the air of your house fresh. That’s where roof vents come in. They protect your home against mold, rot, and even temperature fluctuations by providing ventilation.
The best roof vents remove stale air and bring in Mother Nature’s good old fresh air. Choosing and installing suitable roof vents for your home is easy if you know what you’re doing. This article is your ultimate guide to everything-roof vents.
Take a deep breath, and let’s jump in!
What Are Roof Vents?
Roof vents are the lungs of your house. They make up the brunt of your attic ventilation system. Some roof vents let out stale air while others bring in fresh air.
Regardless of how they work, roof vents protect your roof from heat, moisture, and other factors that can damage its structure.
There are several types of roof vents, but they all fall under one of two general categories: intake vents and exhaust vents. In most cases, it’s best to have both kinds of roof vents.
However, if it’s not architecturally possible for your house to install an intake roof vent, an exhaust one will do just fine. Let’s take a closer look at how each of these ventilation methods works.
How Roof Vents Work: Ventilation Methods
You know the old expression “out with the old, in with new”? Well, that’s generally how roof vents work. Each type of roof vent has a specific mechanism of action, but in general, they either take out old air or bring in the new, fresh air.
In other words, there are two ventilation methods: exhaust and intake.
Exhaust Ventilation: Out With the Old
Let’s start with the first, more common type of ventilation system: exhaust roof vents. These work by letting out the old stale air collected in your attic. Here’s the science behind it.
If your attic space is cramped and has no ventilation, it’s probably pretty hot there. Ever wonder why this is?
Well, it’s the top of your house, right? And we’ve all heard the saying that heat rises. In other words, all the heat collected throughout your house gathers into the top of your house, which is the attic.
In reality, the laws of physics show that it’s not heat that rises but hot air. Hot air is the culprit behind all the heat, moisture, and unpleasant odors you find in your attic. In fact, if it weren’t for all that hot air, your attic probably wouldn’t form any mold or mildew.
This is where exhaust roof vents come in. They’re usually installed at the highest point on your roofline so they can collect all of that rising hot air and let it out.
Intake Ventilation: In With the New
Intake vents work with an opposite mechanism. They bring in the fresh air that’s much cooler than the pent-up, humid, and stale air inside the house.
Cool, fresh air makes sense, right? We want to breathe fresh air. But there’s another scientific reason intake vents work so well.
According to the laws of physics, cold air sinks to the bottom while hot air rises. In other words, when cold air comes in through the intake roof vent, it pushes the hot air out.
That’s why intake roof vents are usually installed near the lower part of your roofline. They come in from the bottom and kick out all of that stale, humid air that exits through the exhaust vents at the top.
This ideal ventilation scenario is where intake and exhaust roof vents work together to keep your home cool, fresh, and healthy.
This is also called vertical ventilation when the two vents work together alongside gravity to promote the natural flow path of air from bottom to top.
The Importance of Roof Vents
Roof vents are very important for the overall health of your house, from the roofline and attic to the interior of your home.
Let’s see how you can benefit from installing roof vents.
Prolonged Roof Lifespan
Roof vents can help protect your roof from extreme heat and extreme cold, extending your roof’s life.
During hot weather, your roof can absorb tons of heat, especially metal roofs, reaching almost double the outside temperature. Poorly ventilated attics can also add to the built-up heat, bringing your roof to scorching temperatures.
Roof vents can help the pent-up air escape and even bring in cool air to lower the temperature of the roof and attic as well.
On the other hand, when it’s extremely cold, roofs are liable to what’s known as ice damming. It’s when icicles form on your roof, and the heat coming from the attic starts melting some of the ice and snow back into the water.
This water runs down the side of your roof and eventually refreezes. Sometimes the water and ice reach certain areas of your roofing material, causing structural damage.
When roof vents do their job in the winter, you might find some snow on your roof but rarely any icicles.
Roof vents can help reduce your energy costs and make your utility bills smaller.
They remove hot air from your house and bring in cool air to replace it. That means the overall temperature of your home is cooler, which reduces the workload of your air conditioning system.
This translates to less energy and a smaller electricity bill.
Prevents Condensation, Rot, and Mold
Humid air that builds up in your attic can undergo condensation when it touches a cold surface, such as the underside of your roof. This condensation often results in an environment that promotes bacterial and mold growth and mildew.
Roof vents help release the humid air from your attic and lower your home’s temperature while keeping it dry. This helps prevent condensation, rot, and mold.
Types of Roof Vents
Now that you know how roof vents work, let’s take a look at the different types of roof vents you’ll find. There are seven main types of exhaust roof vents and four types of intake.
Exhaust Roof Vents
Let’s start with the most common type: exhaust.
1. Ridge Vents (AKA On-Ridge)
This one is the most common type of exhaust roof vent. In fact, when you install a new roof, a contractor will likely include a ridge vent in your quotation because it’s just common practice.
It’s especially important in states with sharp temperature fluctuations, such as Boston, Texas, and Michigan.
Ridge vents are usually installed at the peak or highest point of your roofline because this is where all of the hot air gathers. They typically run through the entire area of your roof, covering a large enough surface area for the air to collect and get out.
During installation, you typically make a gap a couple of inches wide, creating an air slot through which the flexible ridge vent runs across the roofline.
Then, a ridge cap shingle covers the vent to keep environmental factors out and provide an aesthetic finish. A ridge cap shingle usually is optional when installing metal ridge vents.
Ridge vents are usually the first choice for ventilation if they’re not architecturally feasible. For example, you can’t use a ridge vent if there’s no ridge for them to go on.
2. Box (Louver) Vents
Box vents look like tiny boxes on top of your roof, hence the name. They’re placed high up on a roofline but rarely at the peak. After all, it’s hard to put a bunch of boxes on the peak of your roof, right?
This is also why box vents are slightly less effective than ridge vents, although almost as popular.
Depending on your roof’s surface area, you’ll almost always require more than one or two box vents for proper ventilation. Installing a box vent requires cutting a hole in the roof for the vent to fit snugly into.
There are several sizes, but the most popular box vents are usually 18-inch by 18-inch square. Their small size makes them highly versatile and easy to install, but since they can’t cover an entire roof area, you’ll need several vents for ventilation.
Box vents are preferred for smaller rooftops and complicated roof lines with twists, bends, and different elevations.
Note that they’re the second go-to choice when ridge vents can’t be installed.
3. Off-Ridge Vents
Off-ridge vents are metal vents usually installed about a foot below the ridge of a roofline, hence the name. They’re much less popular than ridge and box vents. Off-ridge vents are typically four feet long and made from galvanized steel.
The main problems with these vents are their small size, which only lets a little hot air out compared to other types of roof vents.
They’re usually used as supplemental vents when your main vents, such as a box or ridge vent, can’t access certain roofline areas. Their small sizer comes in handy since they can be added to surface areas of complex roofs that don’t have one continuous roofline.
Off-ridge vents are also great for hipped roofs.
To install an off-ridge roof vent, you’ll need to cut a hole in the roof large enough to accommodate the vent. The ideal location to start is about one foot below the ridge or the highest point on your roofline.
4. Hard-Wired Power Vents
Hard-wired power vents are another form of exhaust ventilation that can push out hot air from your attic space. They have several names, including powered attic vents and powered attic ventilators.
They’re called “powered” because they require energy to work. In the case of hard-wired roof vents, they act as an electricity-powered fan that sucks out the hot air from your attic.
They’re mounted to the top of your roof and connected through an electric circuit to some sort of power source and a home thermostat. Whenever the attic’s temperature rises above a certain degree, the vents push out the hot air for a cooling effect.
While hard-wired power vents are theoretically effective, they’re not the best ventilation option for two reasons.
First of all, being electricity-powered means, they can be expensive. Second, they usually suck up air from the rest of the house to replace the hot air from the attic instead of bringing in fresh air from the outside.
This means if you’re using an air conditioner, you’re losing all of the cold air you’re paying for because it keeps going to the attic while your unit keeps making more cool air.
In other words, you’re spending money to make your house cooler and then throwing that money out through the hard-wired roof vent. You may not notice it immediately with your first utility bill, but your expenses will increase significantly after some time.
Over the years, traditional power vents have been replaced with solar-powered ones.
5. Solar-powered Vents
Solar-powered vents have replaced traditional electricity-powered ones due to their power consumption efficiency. They use almost zero electricity and don’t add charges to your utility bill. You also don’t have to run electric wires and connect them to a power source, which makes them much easier to install.
However, taking the power source out of the question still leaves the issue of how the air circulates from indoors to the attic and out. Solar-powered roof vents, while energy-efficient, still suck up the air from your home to replace the hot air expelled from the attic. Much like hard-wired vents, they can render your air conditioning system futile and ineffective.
6. Cupola Roof Vent
Now here’s a beautiful, highly-aesthetic roof vent option. If you’ve ever seen something that looks like a tiny tower on top of a house that gives it a beautiful, regal look, guess what? It’s a cupola vent.
It’s not just there to make the roof prettier but to provide ventilation and function as an exhaust vent. However, they’re somewhat expensive, hard to install, and only suit some rooftops.
Originally, cupola vents were used in barns to bring in fresh air and help keep hay and other barn components dry. They functioned as both exhaust and intake ventilation systems. However, cupola vents nowadays mainly work to expel hot air.
They’re designed to provide ventilation and also allow extra sunlight into the attic. There are several kinds of cupola vents, but wooden models are the most popular since they’re more resistant to environmental factors.
While cupola roof vents provide great ventilation, they’re usually installed for their aesthetic appeal. Many Italian architects incorporate cupola vents into roof designs when they’re first conceptualized.
Cupola roof vents can even be designed to accommodate one or two people at a time, so they can double as a viewing tower as well as a vent.
So if your main concern is roof ventilation, cupola roof vents won’t be your first choice due to their high cost of design and installation.
7. Wind Turbines or Whirlybird Vents
Whirlybird vents are the last kind of exhaust ventilation you might encounter. They’re called whirlybirds or turbines because they rotate to suck up stale air from your attic and expel it.
Turbine roof vents are made of a series of aluminum blades that are covered with a large aluminum lid or cowl. They rely on external air and wind to rotate the aluminum blades, resulting in a suction force that pulls the hot air out of the attic.
Whirlybird vents don’t need a power source. They rely on good old Mother Nature. This is both good and bad. Being cost-efficient is great. However, being wind-powered means you will get little ventilation on days when there’s little to no wind.
Turbine roof vents typically need a wind of about 5-6 miles per hour to activate the blades’ rotation and the ventilation system. They’re not ideal for windless summer days, especially if you’re not using any other supplemental roof vents.
The great thing about these vents is that they’re eco-friendly. They don’t take up electricity and leave a zero carbon footprint. They’re also easy to maintain. You will only need to revisit them a little after installation, except for lubrication now and then.
Despite being wind-powered, turbine roof vents are very silent. You won’t hear them or even remember they’re there. Compared to noisy hard-wired power vents, turbine vents are convenient.
A downside to whirlybird vents is their size and ventilation power. Being relatively small in size, they can only expel a small amount of hot air at a time. This means you’ll have to add several turbine vents for proper ventilation.
Not only is this expensive, but it might ruin the image of your rooftop. Your best bet is to add it to other ventilation systems.
Intake Roof Vents
Now that you’ve removed all that stale, humid air, you must replace it with fresh, cool air. That’s where intake roof vents come in. They might not be the best option alone, but when paired with an exhaust roof vent, you get the ultimate ventilation cycle.
There are fewer types of intake roof vents than exhaust ones, and they’re as follows:
1. Soffit Vents
Soffit vents are the most commonly used and recommended intake roof vents on the market.
In fact, you’ll find that most contractors recommend a combination of soffit vents as an intake ventilation system paired with ridge vents for exhaust. Together, they make up an extremely efficient ventilation cycle that isn’t too expensive.
Soffit vents are installed under the eaves or the overhang of your roof, which are the protruding part that goes beyond the walls of your home.
This means that soffit vents can only be installed if your roof has eaves or an overhang; otherwise, there’s no place for them.
Generally speaking, there are two kinds of soffit vents: continuous and individual.
- Continuous Soffit Vents
As you may have guessed, continuous soffit vents go along the entire span of your eaves. This saves a lot of money and is usually easier to install in one go compared to individual soffit vents.
Continuous vents also provide better ventilation because of the greater surface area involved. While they can be made from several kinds of material, vinyl is the main go-to option for this type of vent.
The vinyl makes tailoring the vent’s appearance easier to match any house color scheme or design.
- Individual Soffit Vents
Individual soffit vents still go on the eaves of your roof, but they’re smaller, rectangular, and usually spaced apart at 5-6 feet intervals. Being spaced out, they cover a smaller surface area which translates to weaker ventilation efficiency.
It takes more effort to install each vent individually, but it ultimately depends on the roof and eaves’ architecture.
2. Over-Fascia Vent
If your roof’s eaves are too small to fit soffit vents, your contractor might recommend over-fascia vents as a form of intake ventilation.
The typical top-down structure when fascia vents are used is a starter row of shingles, followed by the fascia vent, which rests on the fascia board and gutter. Fascia vents typically cover the entire bottom of a roofline, but they’re only about half an inch in height.
This means fascia vents provide limited ventilation due to the relatively smaller surface area compared to soffit vents. They mainly drive in cool air between the felt and the fascia board, which can be limited.
Over-fascia vents are usually considered when soffit vents are architecturally difficult to install or, in the case of complex roofs.
3. Gable Vents
Gable vents are a simple type of ventilation that often functions as both an exhaust and an intake system. It’s an old, architecturally-unappealing intake vent that takes cool air in from one side of the attic and pushes out hot air from the other side.
This is why gable vents function through horizontal ventilation, which refers to the direction of air movement from one side to another. The majority of roof vents work through vertical ventilation, which moves air from the bottom to the top.
Many problems make gable vents less favorable when it comes to roof vents. For example, they’re only applicable when you have a gable-style roof. Complex rooftops can’t accommodate gable vents because several structures can affect the airflow from one side to the other.
Gable vents take many shapes, but the most common is a triangle-shaped vent that rests below the rooftop peak. And they’re usually made from metal.
One thing worth mentioning is that gable vents work better alone, unlike most roof vents. Combining a soffit or ridge vent with a gable vent is not recommended because of the different ventilation directions.
The horizontal and vertical ventilation can cancel each other out or impede the entire ventilation process.
4. Drip Edge Vents
A drip edge vent is basically the exact same design as a fascia vent, except it has holes that allow water to drain from the roof. It usually goes below the first row of shingles and is made from malleable metal.
It’s not the best in terms of ventilation, but it’s an option to consider when soffit vents are structurally inapplicable.
Metal Roof Vents: What to Install if You Have a Metal Roof
If you have a metal roof, some vents work better than others. They are better at ventilation, can be energy-efficient, and help minimize the condensation often associated with metal roofs.
The best vents for metal roofs are:
- Ridge Vents: Perfect for architectural style metal roofs and can easily blend in with the roof’s aesthetics.
- Gable Vents: Work great for metal roofs but depends on the complexity of your roof design.
- Whirlybird Vents: Metal roofs provide adequate surface area for mounting whirlybird vents.
How Many Roof Vents Do I Need?
The number of roof vents you need depends on two things:
- The surface area of your roof
- Whether or not you have a vapor or moisture barrier
In case your home has a vapor barrier, a general rule of thumb is one square foot of roof vent for every 300 square feet of ceiling space. In other words, go with a ratio of 1:300.
If you don’t have a moisture barrier, go for a ratio of 1:150, meaning 1 square foot of roof vent for every 150 square feet of ceiling space.
Ideally, you want to split the surface area of your roof vents evenly, with half of them providing exhaust ventilation while the other half providing intake ventilation. This is the best scenario where the airflow is balanced, and the roof vents work synergistically.
How to Choose a Roof Vent: Factors to Consider
Choosing a roof vent can be intimidating. Luckily, you can easily choose the right vent if you consider a few factors.
Roof Surface Area and Design
Your roof’s surface area ultimately determines the type and number of roof vents you’ll need. Logically, the greater the size of your roof, the more roof vents you’ll need.
However, your roof’s architectural design determines the type of roof vent. For example, if you have a complex roof with several twists and different elevations, it might be difficult to install continuous, one-piece vents like ridge vents. Continuous soffit vents are also a no-go.
One thing you might want to consider is your electricity bill. Passive ventilation systems require no power source and don’t add to your electricity bill. One example is ridge vents or soffit vents.
On the other hand, active ventilation systems use a fan to force cool air in and hot air out. This might require an electric power source, such as with hard-wired vents, or can be energy-efficient, such as with solar-powered vents.
You don’t want to choose a roof vent that makes your roof look unattractive.
For example, whirlybird vents tend to stick out and aren’t the most subtle or visually-appealing roof vents. On the other hand, ridge vents and cupola vents can easily blend in with your roof’s design.
Frequently Asked Questions
What Is Wind Tunneling?
Wind tunneling is when air travels through one vent and goes out through another, usually on the opposite side of a house. This airflow helps drive in cool air from one side while pushing out the hot, stale air from the other end.
It’s very common in the case of gable vents.
What Are Passive and Active Ventilation?
Passive ventilation involves using natural airflow without any artificial help to bring in cool air or push out the hot, stale air from an attic. Ridge vents are an example of passive ventilation.
On the other hand, active ventilation requires a power source to actively force cool air in and push out hot air with the help of a fan. Powered vents, whether hard-wired or solar-powered, are an example of active ventilation.
Roof vents can prolong the lifespan of your roof, reduce your energy costs, and improve the air quality in your home.
Having both intake and exhaust roof vents is the best ventilation scenario, but a good exhaust vent will do if it’s not possible for your rooftop.
No matter which one you choose, a roof vent is bound to make your house a cooler, fresher, and more comfy home. And if you need help determining which type of roof vent to install, you can always contact a professional to help you with that.