The best roof ventilation systems don’t just extend the life of your roof, they help lower your home’s energy bills and make your house an overall healthier place to live…
Different types of roof vents are more effective than others, but each type of vent has the basic task of either removing stale air from your attic space (exhaust) or bringing fresh air into your home (intake).
If you want to truly take advantage of the benefits of proper roof ventilation, then it is critical to have both intake and exhaust ventilation installed. However, in many cases it is not possible to have intake ventilation because of the home’s architecture. In these cases, having only exhaust is better than nothing! But for the sake of discussion, we can assume your roof’s design can structurally handle both intake and exhaust.
Before covering each type of roof vent available on the marketplace in 2020, let’s first get an overview of the two styles of ventilation in general…
The Two Styles of Ventilation
What is ventilation, anyway? According to Oxford, ventilation is the “provision of fresh air to a room, building, etc.”
It’s out with the old (air) and in with the new (air). In roofing just like in life, this is very refreshing and important strategy to have!
Understanding how air naturally moves helps us realize why both intake and exhaust play a critical role in a roof’s venting ability. And knowing how the two work hand-in-hand is important before choosing which of types of roof vent systems are best for your home and budget.
Exhaust; Let That Stale Air Out
According to West Texas A&M University, Physics Professor Christoper Baird, “heat does not rise, hot air rises. (source)” For the purposes of venting your attic space, this is valuable because it is the hot air, which contains moisture, that you want to get out of your attic space.
If the hot air is allowed to stagnant, it can lead to bad-smelling mildew and eventually mold. This is one of key reasons why ventilation is important to your home’s health, as mentioned above.
Because hot air rises, exhaust-style vents are generally placed towards to top of your roof line. The most common exhaust vent used for modern roofing systems is the ridge vent. At Roof Hub, we install a ridge vent for every single new roof unless the home’s style does not allow for it.
Remember: ridge vents and other exhausts like them allow that hot, humid, moist stale air to exit your home but are only one half of any great venting strategy!
Intake; Bring That Fresh Air In
Hot air leaving your attic is important for your home’s health and roof’s longevity, but hot air is generally pretty stubborn! It doesn’t want to leave without being forced out, so we need something to act as a bouncer. Enter: cooler air.
Cool, fresh air (in form of intake ventilation) is the other half of a great venting strategy. The cooler air comes into your attic space via intake vents that are placed lower on the roof line than the exhaust vents mentioned above. Because the cooler air enters underneath the hot air (and because hot air rises), the intake ventilation will help push the stubborn hot air out of the attic space. The cool air, by way of intake style vents (like a soffit) acts as our bouncer.
As long as you have exhaust vents with a large enough surface area, then this cooler intake air will help thrust the hot air out of the home. In a perfect world, it’s all a complete cycle…
Cool air in through the intake vents and hot air out through the exhaust!
What Happens If My Roof Doesn’t Have Proper Venting?
Rapid destruction of your home, property, and everything you hold dear. All things that matter to you will perish in the most annihilating way imaginable. Just kidding.
Though there may not be world-ending destruction if you do not have proper ventilation, there are significant drawbacks that will effect your attic space, your roof, your home, and your lifestyle. They include:
- Poor indoor air quality due to dead air in the attic space (summer)
- Overburdened HVAC systems (air conditioning) forced to work harder to cool the second (and third, if applicable) floors of your home
- Extra moisture (in form of warm air) in the attic space
- Ice dams in the winter months, if you live in a colder climate
- Dry rot of roof sheathing
The Most Common Types Of Roof Vents
Now that we’ve covered the significance of venting your roof as well as the differences intake and exhaust style vents, it is time for an overview of the most frequently used roof venting systems out there.
7 Type Of Roofing Exhaust Vents
When considering which roof vent is best to use as exhaust for your home, please consult with an experienced roofing specialist before making a final decision.
Most folks install a new roof when they add roof vents, so it is important to get quotes from a trusted roofing contractor anyway.
We add this disclaimer because it is impossible to cover 100% of the pros and cons of each option without knowing the exact setup of your current roof as well as the style of your home.
Ridge Vents (Most Common Exhaust)
Ridge vents are the most commonly installed exhaust vents. If you’re getting a roof quote from a contractor in Massachusetts, then there’s a strong chance that this type of vent is included in your estimate. If a ridge vent is not listed, make sure to ask which exhaust vent the contractor is planning to use and why it is most appropriate for your individual roofing project.
A ridge vent sits at the peak of your roof and runs across the entire span of your roof line. Because ridge vents are located at the roof’s highest point, they are in prime position to let the hottest air escape the attic space. And because they run across the entire roof line, they generally have the surface area necessary for expelling large amounts of hot air.
Important: when used in combination with intake vents that sit at the bottom of your roof line (like a soffit vent), a ridge vent offers the best chance for vertical ventilation.
Vertical ventilation takes advantage of gravity and the natural flow of cool and hot air. Cold air comes up through the bottom, and exits through the top. This strategy is far superior to horizontal or cross-venting, which we will discuss later.
Almost all roofing companies are very familiar with ridge vent installation. The install process involves using a saw to cut a 2 inch wide gap along the entire peak of the roof. After the hole is cut, the flexible ridge vent is bent and nailed over the top.
After the ridge vent is nailed over the newly cut gap at the ridge line, a ridge cap shingle is bent over the vent and nailed on. This special type of shingle is more robust and pliable than a normal asphalt shingle and come in colors that will flawlessly match your new roof!
Most modern ridge vents, like GAF’s Cobra Snow Country ridge vent, are so strong that you can stand on them! Their strength provides extra protection for snow build-up in the Northeast and other snowy regions of the United States. The way the ventilation holes are built into the product generally safeguards against snow and ice accumulation that would otherwise block the exhaust of other style vents.
The design of a ridge vent, its location on the roof line, the surface area covered, as well as cost and commonality are just a few of many reasons that this is one of the most popular exhaust vents out there, and one that we highly recommend if it fits your home’s architecture.
Off Ridge Vents
Though they sound similar in name, an off-ridge vent is only similar to a ridge vent because they both sit close to the crest of your roof. In fact, “off ridge vents” are much more similar to box vents than they are to ridge vents!
Overall, off ridge vents are not a very popular style of vent and not one we recommend when compared to other, more effective exhaust roofing vents. Off ridge vents are not as effective as full ridge vents because they are much smaller and do not sit as high on the roof. Their size prohibits them from expelling a large amount of hot air and their location restricts their ability to vent the absolute hottest air, like a ridge vent.
The most popular off ridge vents on the market are approximately 4 feet in length. Often made of galvanized steel,installation involves cutting a hole the size of the vent itself into the roof approximately one foot below the ridge line.
Off ridge vents are advantageous when the actual ridge line of the roof is small. This can happen with complex roofs and homes that do not have one long, continues ridge line for a traditional ridge vent to run across. Adding an off-ridge vent or two to these types of roofs can provide an added punch of ventilation to areas that don’t have enough.
If your home has lots of peaks, valleys, and dormers, then this may be a type of vent to include in your ventilation system. This will not always be the case however, so make sure you speak with a trustworthy roofer before making the call.
Box Vents (aka Louver Vents)
Box vents are similar to off-ridge vents but are a much more popular venting solution.
One of the main similarities to an off-ridge vent is that the first step for installation is cutting a hole in the roof for the vent to sit over. Another similarity is that box vents are generally installed in bunches across the roof in order to add extra ventilation. Just one or two box vents is not nearly enough to vent your entire roof!
The design of a box vent is more square than it’s off-ridge counterpart, hence the name; box vent. There are a wide range of sizes available to match what’s needed for your space. The most common sized box vent on the market today is 18 inches by 18 inches.
Along with ridge vents, box vents are one of the two most popular exhaust vents you’ll see on a modern-day roof. Their small size is mostly a drawback, but does offer some versatility when compared to a ridge vent. Because they don’t need to run across the entire peak of the roof, box vents can be installed strategically in smaller areas that need air vented but cannot utilize a ridge vent.
Like with off-ridge vents, using a box vent makes sense for more complicated roof lines that have lots of different sections. But if you have a larger roof line, then a ridge vent is most often much more effective. However, off-ridge vents are very commonly used on hipped roofs and if you have a hip roof, then these are a great option.
Hard-Wired Powered Attic Vents
Powered attic vents, also known as powered attic ventilators or attic power vents, are electric-propelled fans that help pull stale air out of an attic space. They work much like a box fan placed in a window on a hot summer day. They can effectively pull the hot air out, but come with a tradeoff of higher electricity costs.
Overall, one of the main reasons for attic ventilation is keeping your attic at a constant temperature when compared to the rest of your home. In the summer the space may be a little warmer and a little cooler in the winter, but what we are trying to avoid is extreme temperature fluctuations from season to season. This is important to note when discussing powered attic vents because their power can often be either detrimental to a ventilation strategy, or not powerful enough to make a difference at all…
According to Danny Parker and John Sherwin at the Florida Solar Energy Center, “vent fans have the potential to reduce measured peak summer attic air temperatures by over 20 degrees farenheit. However, the impact over the cooling season is fairly modest with well insulated attics.”
Another point mentioned in Parker and Sherwin’s abstract is that the study took place in an area where homes are heavily air conditioned. This suggests that the powered vents could actually be pulling cooler air up through the main floors of the home and out of the attic, thereby increasing energy costs and forcing the air conditioning unit work harder. If you wouldn’t place a box fan in a window when there’s air conditioning cooling that same room, then it may not make sense to use a powered attic vent if you are utilizing air conditioning to cool the entire home.
Finally, Parker and Sherwin note that the existing homes in the study did not originally have a exhaust ventilation, like a ridge vent. This is a major point because the addition of any exhaust to a system lacking one would be beneficial, whether that vent is powered or non-powered.
Weaker powered vent units can be just as damaging to your home’s ventilation strategy as the strong ones mentioned above. According to other homeowner reports, weaker power vents have a tendency to circulate air rather than expel air. While a consistent air flow is important for avoiding mildew buildup, what’s needed most is the discharge of hot air from the attic. And weak powered vents just don’t cut it.
On top of the apparently complex downsides mentioned above, you have the electricity costs. Hard-wired power attic vents need to be plugged into your home’s power source, inevitably increasing your energy bills. Though the added costs may be small over days or weeks, the increases start to add up over the course of months and years. Higher operational costs is a substantial reason why traditional hard-wired systems have transitioned to solar power over the last few years.
Solar Powered Attic Vents
Solar-powered attic ventilation removes almost 100% of the electricity costs associated with older hard-wired vents but does not eliminate the negatives that come with powered attic vents in general.
Simply removing electricity costs does not change the way the unit operates. The fans are often either too powerful, or not powerful enough. There’s unfortunately no way to guarantee you get it just right. And when added on top of a proper vertical ventilation strategy (like a ridge vent exhaust and soffit vent intake), powered vents can actually have damaging effects that wouldn’t have otherwise existed. More is not always better!
For these reasons, it is best to use more natural, time-tested methods of exhaust for your roof. If you already have proper venting in your attic, then you are better off without the addition of a powered fan, even if it is run on solar panels.
Roof Turbines (aka Whirlybird Ventilation)
Whirlybird is a fun word to say, and we consider this a significant benefit to owning a roof turbine. You get to stand in your driveway, point at your house, and exclaim to your neighbors: “you see that, that’s my whirlybird.” Wind turbines aren’t all fun and games however, there are meaningful pros and cons that can effect the health of your roof and the ventilation of your attic.
Whirlybird vents were originally invented in the early 1900’s by British Inventor Samuel Ewart. The device consisted of aluminum blades inside an aluminum “cowl,” or covering, which rotate using wind from outside the house to then pull air up from inside the attic and out of the house. Ewart’s original design remains consistent with modern-day whirlybird models.
Roof turbines need winds of at least 5 to 6 miles per hour to activate and spin the interior blades, which means that they won’t be effective on days with a slight breeze or no breeze at all. If this is only form of exhaust on your roof, then you’ll run into trouble on hot summer days without any wind.
Even on days with lots of wind, the strength of whirlybirds as a ventilation tool is questionable. They are often smaller than a box vent or off-ridge vent, which limits the amount of hot air they can pull out of the attic space. In order for this to be an efficient venting strategy, most homes will need a handful of roof turbines to have a noticeable impact on the roof’s exhaust.
Whirlybird roof turbines may not be the most effective way to ventilate your roof, but there are some benefits to using them. First, they eco-friendly and green because they do not require electricity. With the exception of occasionally lubing of the unit, there is little to no maintenance or upkeep required with ownership. And unlike the power vents mentioned earlier, they are quite silent even on a windy days where gusts exceed 20 miles per hour.
If you’re wondering what that tower-looking thing on your roof is, you may be the proud owner of cupola vent!
Cupola vents are one of the least common types of roof vents because of their cost, complexity and because not everyone has the primary problem they were designed to solve.
The origins of cupola vents stem from use in barns. They were originally created to allow lots of air into a barn’s loft in order to help dry hay and other crops stored in the structure. In their original form, cupola vents acted as both an exhaust and intake. In modern day roofing and design however, one of the main reasons to use a cupola vent is to allow extra light into an area underneath the vent.
Cupola vents come in many different shapes and styles. Some have wooden louvers around the openings to protect against the elements, while others are wide open in order to maximize the amount of light and air that enters the space below.
Many Italian-inspired homes have cupola vents built into the roof line for multi-use purposes. First, because they’re a form of ventilation. But more importantly, because they add a nice pop to the home’s architectural design. A beautiful cupola vent can add lots of character and charm to an otherwise boring roof line. Some more elaborate cupola vent styles even have windows and enough room for a person or two to enter the space. What a fantastic location to spy on your neighbors from!
The higher costs associated with building out a brand new cupola vent combined with similar efficiency when compared to larger box vents make cupola vents an unnecessary cost for most homeowners. Unless your main concern is added curb appeal, cupola vents don’t make much sense.
However, if you need extra roof ventilation and don’t mind paying a premium to make your home look nicer, then a cupola vent may be for you. Otherwise, a few large box vents will do the trick!
4 Intake Ventilation Solutions For Your Home
With all the ways you can get that musty old air out of your attic, we’d be remiss without diving into ways to replace it with new, fresh air from the great outdoors.
Exhaust ventilation without any intake is like having a bike without pedals. The air may be able to move a little, but it won’t get very far!
Paired with proper exhaust (like a ridge vent, or an ample amount of box vents), adequate intake ventilation brings fresh air into the attic and up through the exhaust. This is classic vertical ventilation at it’s finest! A new stream of fresh air comes in, and the old hot air is pushed out.
Unlike with exhaust, there are less styles of intake for your roof to consider. And in most cases, we strongly suggest the first option on the list.
Soffit Vents (Most Popular Intake Vent)
Soffit ventilation is by far the most popular form of roof intake venting. It forms one half of the most popular combination of intake and exhaust; soffit vents (for intake) with a ridge vent (for exhaust).
Soffit vents are a favorite amongst home builders and roofers because they are unquestionably the most effective intake vent for the cost. If a home’s style allows for it, most new construction builders include soffit vents in their home’s blueprint.
What is a soffit vent, exactly?
Soffits are intake vents that installed directly on your eaves, which are located directly underneath your roof line. Some folks refer to this area as the “roof overhang”.
There are different types of soffit, but almost all of the most common designs have small holes that allow cool air to flow into your attic space, where it helps push hot air out of your home through the exhaust vent. And do not fret, the soffit’s holes are very small, so unwelcome critters cannot make their way into your house.
Because not all homes are the same, there are two types of soffit vents designed to fit most styles: continuous soffit vents and individual soffit vents.
Continuous soffit vents are longer, and often wrap around the entire eaves of a home. Much like a ridge vent (which runs along the entire peak of a roof), continuous soffits provide lots of bang for your buck because there is more surface area. The greater the surface area, the more air can pass through. Continuous soffits are generally made of vinyl with intake holes drilled in. Because they’re vinyl, they come on a wide array of textures and colors to match the look and feel of almost any home.
If continuous soffit vents are like the ridge vents of the intake world, then individual soffit vents (our second type of soffit ventilation) are more like box vents. They’re smaller, generally rectangular in shape, and are placed 5 to 6 feet apart along the eaves. Because individual soffits are spaced out, they are not as effective as continuous systems because they provide less surface area for air intake.
Whether an individual or continuous style best fits your home, soffit vents are the base of any great vertical ventilation system. When combined with a ridge vent, soffits pull large amounts of cool into the home from underneath the eaves then help push the hot air out. When it comes to effectiveness, there is really no comparison when put up against the following intake vents.
Gable vents are an older, somewhat outdated, style of intake that also partially functions as an exhaust system. Unlike with vertical ventilation discussed throughout this article, gable vents utilize horizontal or cross-ventilation to help keep air moving through the attic space. The basic premise is that air flows in on one side of the attic, then out through the other.
A gable vent is mostly used with a gable style roof because a vent can be placed on each side of the home. These vents are not as effective on more complex roof styles because the cross breeze can be impeded by rafter beams, peaks, valleys, dormers and other parts of the roof.
Gable vents come in all shapes and sizes, with the most popular being a triangular shape that sits directly below the peak of the roofing system. They are sometimes made of wood or vinyl, but metal is the most popular.
Important: while more surface area for venting is generally better when it comes to roofing, you should be careful of combining a gable vent with any vertical ventilation strategy. We give this warning because the cross breeze often disrupts any air flowing from a vertical intake (like a soffit) through to the vertical exhaust (like a ridge vent). The purpose of using the soffit and ridge vent is defeated when gable vents enter the picture.
Over Fascia Vents
Fascia vents, or over-fascia vents, are a newer form of roofing intake that are designed primarily for roofs that do not have sufficiently sized eaves to fit soffit vents. A fascia vent is placed at the top of the fascia board and gutter and directly underneath the starter row of shingles.
The basic premise behind fascia vents is to allow air intake where the wind hits the roof, opposed to a soffit vent with relies on air rising.
The potency of over-fascia vents is questionable because of their small surface area. Although they generally stretch across the entire bottom of the roof line, they are only about ½ an inch in height. This is a drastic decrease in available airflow when compared to the surface area of soffit ventilation.
Over fascia vents are recommended for homes where soffit vents cannot be used and on more complex roofs where the use of soffit vents alone wouldn’t be adequate.
Drip Edge Vents
The pros and cons of a fascia vent hold true for drip edge vents because the two are very similar in design and effectiveness. With both drip edge and fascia vents, the air intake is designed to hit the roof head-on, then pull the cool air up the interior roof wall towards any exhaust vent at the roof’s peak.
Drip edge vents differ from fascia vents because of where they are installed. The drip edge is a roofing material that goes directly underneath the first row of shingles and is designed to help drain water into the gutters. It is generally made of a malleable metal. A drip edge vent incorporates intake into the classic roofing material, with small holes either drilled into the drip edge itself, or attached to the drip edge as an add-on.
As you can imagine, installation is notably complicated and should only be completed by a professional.
Like fascia vents, drip edge vents are great for roofs that are unable to utilize sufficient soffit vents for their air intake but do not hold a candle to soffit vents.
Which type of vent is best for my roof?
In most cases, we recommend soffit vents for intake and a ridge vent for exhaust.
For homes that cannot have a ridge vent, box vents are generally the second best option for exhaust. And for homes that cannot have soffit ventilation, you will find that fascia vents to be your second best bet.
With all this being said, every home is different. While the best vent for your roof will vary depending on your home’s style and the shape of your roof, we can agree on two points:
First, having both intake and exhaust vents is better than having only one. And second, vertical ventilation is far more effective than horizontal or cross ventilation.
If you need a new roof and would like to discuss which venting strategy is best for your home, we’re here to help. Give us a call at 857-237-7648 or submit a roof estimate request.