Best Roof Ventilation Methods
There Are Two Main Types Of Roof Ventilation, Passive And Active. Which One Is The Best Choice?
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Roof Ventilation Is Extremely Important
Few people give much thought to roofs. In fact, it’s often not until a roof malfunctions that most homeowners begin realizing how important the roof is, and just how complex roofing matters can get. One key thing that is important to understand is roof ventilation.
We all know that hot air rises up. This means that during those hot summer months, hot and, at times, moist air will rise towards the roof. Aside from increasing the temperatures in the attic and rooms next to the roof, this hot, humid air provides an excellent environment for mold and rot. It doesn’t end there as the hot air near the roof exposes your shingles to prolonged heat. This will cause them to age prematurely.
The heat buildup in the attic also increases temperatures in your house, making your HVAC system work harder, hence higher energy costs. You are not safe in a cold climate either.
During winter, warm, moist air from the house will find its way to the attic. When this happens, condensation will occur on the roof’s interior structural elements and the attic itself. This can cause wood rot and encourage mold and mildew to grow on the attic insulation.
The trapped hot air in the attic will also melt the snow on the roof, causing it to freeze again on the eaves and form ice dams. All these occurrences are disastrous to your roofing structures and will shorten your roof’s lifespan and void your warranty.
Proper roof ventilation makes your house habitable in summer and winter. This is because good ventilation maintains good air quality by removing hot, humid air from the interior of the house. Venting your roof adequately also helps extend the lifespan of your roof and your HVAC systems which are undoubtedly among the most expensive things in a house.
How Roof Vents Work
Simply put, ventilation takes in fresh air from the outside and pushes stale air from the inside of your house. Understanding the natural movement of air helps us understand why intake and exhaust are fundamental to a roof ventilation system.
In addition, understanding how these work together is also central in helping you understand the different vent types and which ones would be ideal for your home.
Intake vents are designed to bring in fresh, crisp air from the outside into the home’s interior. Expelling hot air from the inside of your house is fundamental to the longevity of your roof and your home’s health. However, hot air will not leave the house willingly; it must be pushed out. This requires something to act as a bouncer, and cool air does a great job at that.
Cooler air enters your home through the attic via intake vents. These are strategically placed under the roofline where exhaust vents sit. This means the cooler air will enter the attic under the hot air (because hot air will rise to the topmost part of the attic).
Cool air from the intake vents can push hot air out of the attic from this position. The goal is to have exhaust vents with a surface area that’s large enough to push stubborn hot air out of your home.
Best Roof Ventilation Methods
It’s always advisable to consult with a reputable roofing specialist before settling on a roof ventilation method for your home. Even as you do this, it doesn’t hurt to know what the main roof ventilation types entail. Here is a look at some of the best exhaust and intake roof ventilation methods we have today.
Here are the top exhaust types and how they work.
These are the most commonly installed exhaust vents. A ridge vent is installed on the peak of your roof. Once in place, it runs along the entire length of your roofline. Their placement at the highest point of a roof means they are best positioned to allow hot air to escape from the attic.
Additionally, they run across the entire roof apex, giving them an adequate surface area for simultaneously expelling large amounts of air. When a ridge vent is complimented by an intake vent placed below the roofline like a soffit vent, the system offers the best chances of vertical ventilation. Let’s take a look at how this works.
Vertical ventilation takes advantage of the natural flow of cold and hot air and gravity. In this system, cold air will come in through the bottom and exit through the top. Aside from its performance, ridge vents are familiar to most installers, meaning you will likely get the job down right.
To have it in place, a 2-inch wide gap is curved along the peak of the roofline, from end to end. The ridge vent is then laid and nailed over the top. A ridge cap shingle is then bent and laid over the ridge vent. This is a sturdier, more pliable shingle and comes in various colors, allowing you to find one that compliments your roof’s aesthetics.
Off-ridge vents are only similar to ridge vents in that they sit at higher parts of the roof. However, they are much smaller and are positioned lower down the roof’s peak.
A typical off ridge vent is 4 feet long and made of galvanized steel. To install it, a hole the size of the vent is cut one foot below the ridgeline. Off ridge vents can be advantageous on roofs with small ridgelines.
This is often the case, with unique roof lines that don’t bear the traditional long ridgeline at the roof’s peak. The same goes for houses with multiple peaks, valleys, and dormers. For roofs like this, having multiple off-ridge vents will handle the roof ventilation optimally.
These are similar to off-ridge vents, only more popular. They are also known as louvers, turtle vents, low-profile vents, and flat vents. Box vents have no moveable bits, which classifies them under static vents.
What they do is create an opening for hot air in the attic to escape through. This is mainly through natural convection. Box vents are installed in bunches across a roof by cutting holes on the roof for the vents to sit over.
You need to have several of these strategically placed across a roof to provide adequate ventilation.
Unfortunately, one or two box vents are not anywhere near enough to vent most homes. These vents come in different sizes, with the most common vent measuring 18 inches by 18 inches. Over the years, box vents have become the second most common roof vents, following ridge vents.
While their small size is just about their only undoing, box vents do offer versatility as their size allows for multiple, strategic installations. Box vents largely depend on natural convection, which at times limits their effectiveness.
These are aluminum blades encased in an aluminum ‘cowl’ or casing. The blades use wind outside the house to rotate, pulling fresh air from outside into the attic.
For roof turbines to rotate, they require winds of at least 5 to 6 miles per hour. This naturally makes them less effective on slow wind days or days where wind speeds are below optimal. Therefore, this vent type will often require a backup plan; otherwise, you will run into some problems in hot, calm summer months.
This is not their only limitation, however. Roof turbines are also relatively small in size. This limits the amount of hot air they can pull from the attic. To have any meaningful effect on a house’s ventilation, homeowners need to install a handful of roof turbines. One or a coupe is simply not enough.
Hard-Wired Powered Attic Vents
Powered attic vents are also known as attic power vents or powered attic ventilators. These electric-powered vents have motors driving huge fans. This mechanism is what removes hot air and moisture from your attic. Powered attic vents are very efficient in circulating air. They’re, however, associated with high power bills.
Some additional features of powered vents are adjustable thermostats. This can turn on the fan when attic temperatures reach a certain level. They can also have humidistats that set off the fan once the humidity levels reach a specific level.
The general reason for installing roof ventilation is to keep your attic at a constant temperature in relation to the rest of your house. Of course, your home can get cooler during winter and warmer in the summer, but what you will be trying to achieve is drastic fluctuations from one season to the next.
This is important to keep in mind when choosing powered vents because their power can interfere with your overall ventilation strategy. A weak powered attic vent, on the other hand, can fail to do its job effectively, leaving you with ventilation problems like structural damage.
Weaker vents tend to circulate air, as opposed to expelling stale air. Consistent airflow is fundamental to a home and is key in preventing mildew buildup. However, what you need most, and the point of roof ventilation, is to remove hot air from the attic.
Power vents will operate quietly, at times even when faulty. While this is a good quality, for the most part, it can also make it impossible to tell when your vent is malfunctioning. So if you go for a powered vent, ensure regular inspections.
Once exhaust vents push out stale air, intake vents need to bring in fresh air. So let’s look at some intake vents as well.
This is by far the most popular type of intake venting and is almost always paired with the ever-popular ridge vent. Soffit vents are installed in the eaves of your roof.
This is directly underneath your roofline, also known as the roof overhang. They have different designs, but the most common designs feature small holes that let air in and into the attic. Once this air enters the attic, it naturally pushes the hot air above it out of the attic through the exhaust vent.
You might be wondering about critters and soffit holes. These shouldn’t worry you much because the holes are too tiny to allow critters in.
This is an older type of intake vent that also partially functions as an exhaust system. Gable vents use cross-ventilation or horizontal ventilation to keep air moving in the attic.
The general principle is that air flows in from one gable vent on one end of the roof and leaves the attic via another gable vent at the other end. The gable vent is named so because it’s used on houses with gable roofs.
Unfortunately, the vents are not ideal for homes with more complex roof designs. The reason is simple. Other roof designs might also feature peaks, dormers, valleys, rafter beams, and other roofing parts. These will most likely interfere with the cross beams and the ventilation system.
Over Fascia Vents
Over-fascia and fascia vents are a more modern form of intake designed for roofs with inadequately sized eaves to fit soffit vents. A fascia vent is placed at the top of a fascia board and gutter.
This is right underneath the first row of shingles. The idea behind this is to allow air intake when the wind hits the roof. Over fascia vents span the entire length of the roofline but still have a small surface area because they are often half an inch in height.
Compared to a soffit vent, over fascia vents supports significantly lower airflow levels. As such, these vents are ideal for roofs whose designs are too complex to be adequately served by soffit vents alone.
Talk To The Experts
At Maxx Roof LLC Lakewood, we take a lot of pride in ensuring that our clients get the best of the best. If you are looking for the best roofing ventilation for your home or commercial property, call us for a consultation today, and let us handle the rest.
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Maxx Roof LLC Denver serves the Denver metro area and the surrounding areas. Some of the cities we serve are Denver, Lakewood, Castle Rock, Arvada, Aurora, Boulder, Broomfield, Littleton, Englewood, Centennial, Parker, Thornton, Wheat Ridge, Golden, Morrison, Brighton, Commerce City, Watkins, Highlands Ranch, Lone Tree, Edgewater & beyond.
If your home or commercial property is located anywhere throughout the greater Denver metro area, give us a call for a free inspection & estimate. When you choose to work with Maxx Roof LLC Denver, your are choosing to work with a roofing contractor you can count on, every step of the way.