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In this article we are going to discuss the importance of roof ventilation. Roof ventilation can affect the comfort level of the interior of your home and plays a major role in sustaining the health of your roof. Keep reading to learn about the different types of roofing ventilation, what proper roof ventilation can do for your home, and what the signs of poor roofing ventilation are.
Roofing ventilation provides air circulation through a system of intake and exhaust vents. The purpose of roofing ventilation is to keep the inside of a home comfortable. Without proper roofing ventilation, hot air becomes trapped within the home and can cause a number of problems. There are a few things that determine how a roof is ventilated, including the climate in which you live, the size of your home, the pitch of your roof, and more.
First, we’ll discuss natural ventilation. Hot air within a home rises and causes pressure in the attic. If the air has an outlet from which it can escape, it is replaced by cool, low-pressure air. Roof vents allow for the natural flow of air through the home, keeping it comfortable. Natural ventilation can also be achieved through doors, windows, and other openings in the home.
Next, let’s talk about mechanical ventilation. Some buildings may need a system of mechanical vents to achieve proper roof ventilation. This is usually necessary when the design of the roof does not allow for much air flow, or the structure is located in an area that does not receive much wind. Mechanical ventilation requires a power source to provide constant air flow.
Without proper roofing ventilation, warm air can become trapped in your home leading to costly repairs and a shortened roof lifespan. Roofing ventilation is especially important in climates where there is the potential for extreme temperature fluctuations. Hot air becomes trapped in the home’s attic, making it difficult to keep your home cool in the summers. Once it’s trapped in the attic, hot air can cause mold, mildew, or ice dams in the winter.
The main reason for attic ventilation is to maintain a constant temperature in your attic when compared to the rest of your home. It’s normal for the attic to be a little warmer in the summer and cooler in the winter, but it’s best to avoid extreme temperature fluctuations from season to season.
If you don’t have proper roof ventilation, chances are you are overworking your A/C unit. Your A/C unit will struggle to keep up during the hot summer months to account for the hot air trapped indoors. This added stress on your HVAC system can shorten the life of your unit. If your A/C has broken down multiple times, there’s a good chance that you have a roof ventilation problem.
Another common problem with improperly vented roofing systems is hot or cold areas within the home. If there’s a noticeable increase in temperature from room to room or from downstairs to upstairs, you may have an issue with your roofing ventilation. Very hot or cold areas in the home is a clear signal that your HVAC and ventilation systems are not meeting the demand being placed on them.
Roof leaks, mold, and mildew are a serious sign of poor roof ventilation. Any of these can lead to serious problems and over time, both for your home and for your health. When your roof is exposed to water damage over time, the excess moisture can create additional problems like mold and mildew.
Some roof ventilation problems can allow for unwanted insects or pests gaining entry to your home. Any past damage to roofing, gutters, or siding that hasn’t been addressed can become a possible entry point for pests. Once inside, they can do expensive damage to ductwork and insulation among other things.
We are experiencing increasingly cold winters in central Texas, which means that icicles and ice dams can become a concern. Ice dams are a good indicator that you may have a roof ventilation problem. Ice dams form when the roof heats up, melts the snow, and then the running water freezes once it reaches the edge of the roof.
If you are getting a roof replacement, this is a great time to improve your roof’s ventilation. Roof vent installation is easily accomplished during a new roof installation since most ventilation options can be installed under the roof shingles or mounted outside the roof.
The number and type of roof vents you need depends mostly on the size of your roof, the square footage of your attic, and whether or not your attic has a vapor barrier. Highly sloped attics will have more volume and may need more vents. Keep reading to learn more about the different types of roof vents available.
There are different types of exhaust vents, but they all allow hot, moist air to escape the home.
Ridge vents are the most commonly installed exhaust vents. Ridge vents are installed at the peak of the roof, under the shingles, running the entire span of your ridgeline. Therefore, a ridge vent is easily installed during a routine re-roofing project. Due to their location, ridge vents are in the best position to let the hottest air escape the home’s attic and have the surface area that is necessary to expel large amounts of hot air.
If a ridge vent is used in combination with an intake vent at the bottom of your roof line, you will benefit from vertical ventilation which takes advantage of gravity and the natural flow of hot and cool air. In vertical ventilation, cool air enters the bottom and hot air exits the top.
Turbine vents are attached on the outside of the roof. Originally invented in the early 1900s, a turbine vent is designed to catch wind and air flow in its turbines. It functions by rotating using wind from outside of the house to rotate and pulls the hot air up from inside of the attic and expels it out of the home. Turbine vents need wind at speeds of at least 5 to 6 miles per hour to activate so if they are the only form of exhaust on your roof, you won’t have proper ventilation on hot summer days with no wind. Most homes need several turbines to be effective, but they don’t have any associated energy costs, are low maintenance, and run silently.
Box vents are a popular venting solution and are installed in groups across the roof to add extra ventilation. There are different sizes of box vents available depending on the needs of your home. Box vents are most useful when providing ventilation for smaller ridge areas where a ridge vent cannot be installed. Box vents work well for complex roof lines with various sections.
Power vents, or attic power vents, are a mechanical roof ventilation option for homes that don’t get a lot of exposure to wind. A power vent utilizes fans that run continuously on electricity to pull stale air out of the attic space. Power vents ensure the home is getting the proper roof ventilation but can add to electricity costs. The goal is to help the attic avoid extreme temperature fluctuations from season to season and weak power vents won’t get the job done. It’s important to make sure that the power vent is capable of doing more than simply circulating the air.
Solar powered attic vents are a great alternative to hardwired vents because they remove the associated electricity costs. They still face some of the issues that traditional hardwired power vents have, either by being too powerful or not powerful enough. If your attic is already properly vented, there’s no reason to add more ventilation.
Cupola vents are probably the least common types of roof vents due to their cost and complexity. Originally used in barns, cupola vents allowed air into the barn’s loft to help dry hay stored there. Cupola vents were designed to provide both exhaust and intake, but modern cupola vents allow extra light into the area beneath the vent. Some cupola vents have louvers around the openings to protect against the elements and others are completely open to allow for maximum light and air. Cupola vents are commonly used in Italian inspired architecture and add style to the roofline. Cupola vents are an unnecessary cost for most homeowners, but if you want to add architectural interest to your roof, this may be an option for you.
While exhaust vents release the hot air that accumulates in the attic, intake vents strengthen the air flow process. Intake vents cycle cool air throughout the home and help prevent overheating. There are less styles of intake vents, but when paired properly with exhaust vents you can create a very efficient roof ventilation system for your home.
Soffit vents, or edge vents can be installed under soffits or under the shingles near the drip edge by the gutters. This is the most popular form of roof intake venting used in combination with a ridge vent. Soffit vents are installed directly on your home’s eaves. The most common design of soffit vents has small holes that allow cool air to flow into your attic space, helping push the hot air up through the exhaust vents. The holes are very small so that they do not allow for pests to gain access to your home.
There are two types of soffit vents, continuous soffit vents and individual soffit vents. Continuous soffit vents are longer and wrap around the home’s eaves, providing more surface area allowing more air to pass through. Individual soffit vents are spaced about 6 feet apart on the eaves under your roofline. They have less surface area for air intake than continuous soffit vents, but it depends on which design fits your home’s needs best.
Gable vents are a style of intake vent that also partially functions as an exhaust system. Gable vents utilize horizontal, or cross-ventilation to keep air moving through the attic space. Cross-ventilation relies on air flowing in on one side of the attic and out through the other. Gable vents are most commonly used with gable roofs because a vent can be placed on each side of the home to create the cross-ventilation. Gable vents come in a variety of shapes and sizes. Gable vents are not as effective for more complex roof styles because the cross breeze can be impeded by rafters, peaks, valleys, or dormers. If your roof already uses a vertical ventilation system, you many want to be careful adding any cross-ventilation as it could potentially disrupt vertical air intake.
Over fascia vents and drip edge vents can be used when the eaves don’t provide adequate space for soffit vents. Due to their decreased surface area, these vents are not as efficient as soffit vents, but are typically used when the home’s design does not allow for soffit vents. They rely on air hitting the vent directly rather than soffit vents which rely on air rising.
Energy savings are one of the most important benefits of adequate roof ventilation. Poor ventilation can lead to higher attic temperatures, which of course affects the temperature in the rest of the home. Higher temperatures lead to higher cooling costs as well as stress on your HVAC system. This burden on your HVAC unit can lead to repairs and premature replacement of the unit.
Increased comfort and health is another benefit of proper roof ventilation. Inadequate roof ventilation can cause mold and mildew growth. Most concerning is that mold and mildew can pose health risks to you and your family. Proper roof ventilation will also make the home more comfortable with more stable temperatures within the home.
Proper roof ventilation has the potential to prolong the life of your roof. A roof is a significant investment in your home. Mold and mildew can damage your roof, leading to costly repairs and it can significantly shorten the lifespan of your roof. When shingles get hot due to an overheated attic, they age prematurely. Ice dams, which we discussed earlier, damage shingles and eaves, and can even cause roof leaks over time. Moisture and condensation buildup from an improperly vented roof and can lead to swelling and rot. Aside from the obvious mold and mildew concerns, this can result in nails not holding and reduced roof capacity as well as cracked, flaking shingles.
While it is true that a roof can have too many exhaust vents, the number of intake vents is not a problem. Too many vents can result in poor airflow, which will cause problems in extreme weather conditions. Air from excess intake vents will simply be moved outside of the house through the exhaust vents.
There is no one size fits all venting solution. The best vents for your roof will depend on your home’s style, the design of your roof, and the square footage of your attic space. It’s best to have both intake and exhaust vents and if possible vertical ventilation is more effective than cross-ventilation.
At Orbit Roofing we want to help homeowners get the most value out of their roof. Call us at (512) 957-0155 to discuss your home’s ventilation strategy.
