The type of vents and how many you install will determine how well your home is ventilated. It is crucial to ensure that you have the right amount of vented space per hundred square foot of roof, if not, your roof will not be adequately cooled costing you more money in energy costs to cool your home and risking moisture damage to your roofing members.
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- What is a roof vent, and what is its purpose?
- Is it a necessity to have ventilation on your roof?
- A list of the different types of vents.
- How many air vents do I need in my roof?
- What is the best roof vent?
What is a roof vent, and what are their purpose?
A roof vent is a roofing member that is designed to allow air to pass through your roof or attic freely. They keep your attic free from the hot and humid air that poses a risk of damaging your roof.
By pairing an intake vent with an exhaust vent, this keeps a constant stream of fresh and dry air passing through your roof. This circulation of air preserves the life of your roofing members, and the goods stored in your attic. It also saves you money on energy bills by lowering the amount of work your central cooling system will have to do, as a conditioned roof will mean your home is also cooler.
Your roof needs to have the right amount of intake and exhaust vents; failure on either will mean your roof will not be adequately cooled. Should this be the case, the humidity will rise in your attic, risking severe damage to the roofing members.
Are roof vents necessary?
Yes, these vents are imperative to the overall health of your roof and roofing members. With the constant supply of dry air, it ensures your attic is free from mold.
This mold will damage your roofing members if left for too long. It is for this reason that you should have the right amount of vents to make sure that your roof is dry and free from humidity.
Having adequate air flow through your roof also assists in keeping your home cool. This will save you money on energy for keeping your home temperatures reasonable.
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What are the different types of roof vents?
The roof ridge vent is a continuous vent that runs the topmost point of a roof. It is static and does not have any moving parts, meaning maintenance is very low. They are the most aesthetically pleasing due to their small form factor and are easy to hide.
With the vent running the entire length of the roof, you will be at no risk of having too little ventilation in your attic if installed correctly. They are very effective at releasing hot and humid air out and are very efficient when paired successfully with an intake vent like the soffit.
The roof will have a long and healthy life span due to the formation of a vacuum that keeps dry air running through it. Correctly installed ridge and soffit vents reduce the risk of hot spots forming in the roof, lengthening the lifespan of all roofing members. It is for these reasons that I recommend the ridge vents the most to clients.
Gable vents are a ventilation system only installed on roofs with a gable, which is the triangular part of a wall located at the ridge of a roof. This ventilation system can work great for ventilating your attic but does have some drawbacks.
Gable vents allow for a breeze to blow through the attic from one end to the other; this allows for that dry air to push out the humid air that is sitting static in your attic. But what happens if there is no breeze blowing directly at the gable end vent?
That is the big downfall for gable vents; if no breeze is blowing straight against the vent itself into your roof, this hinders its ability to cool your attic effectively.
These vents require no power, but their effectiveness comes from the wind that drives the vent to extract hot and humid air out of your roof. As long as there is a constant breeze outside, this vent can be very efficient.
This vent does, however, allow for hot-spots to form in your roof as you can only place so many of them, meaning they are not 100% effective and keeping your attic temperatures conditioned. Another downside is that if it is not windy, the vent will not be powered at all, meaning it will be just as effective as a box vent.
I would highly recommend if you are going to go for this option, you do not go for the cheapest option, they tend to squeak and do not have a long life span. Get wind turbines that have ball bearings to reduce noise and improve the life span.
Often referred to as turtle vents, louvers, or flat vents are static vents that have no moving parts. Pairing box vents with intake vents create a vacuum in the attic, expelling hot and humid air out of the roof.
For best practice, install these vents as close to the roof ridge as possible, but unfortunately, due to their size, if you do not have enough installed, hot spots can still form in your roof, risking moisture damage to your roofing members.
They come in all different colors, which is excellent as you can personalize them for your home, so they do not stick out like a sore thumb, but they do have a rather large frame, so bear that in mind.
Off ridge vent
Off ridge vents are often mistaken for box vents, but what makes them different is that they are installed very close to the roofs ridge, and are a rectangular shape and not a square shape like the box vent.
The long edge of these vents is installed along the ridge and as high as possible to try to ensure the best performance for keeping your roof dry.
You would typically need several units to cool your roof effectively, meaning there is quite a high cost if you choose this option. They are usually made out of galvanized steel and come in many different colors.
A static vent, when placed on the topmost point of a roof, can be functional, allowing for hot air to escape from it, however, used mainly as a decorative feature.
However, roofing professionals would not recommend only using this one vent, as way more will be needed to cool your roof and keep moisture out effectively. This vent is mostly used as decoration and as a support vent to an already working ventilation system.
Equipped with motors that drive a fan, PAVs or Powered Attic Vents are designed to expel hot air out of your attic. These can be great as it does not require perfect conditions for them to work much like other vents. These are not perfect and do have some dangerous drawbacks you should consider beforehand.
These fans have to be powered, costing you money in energy. There are solutions if you are happy to spend a little more for the vent system you can look into purchasing vents powered by a battery and solar panel, though these would only work with a charged battery. If the sun is scarce, that is going to hinder the ability for the fan to run.
While I would not recommend these vents, you may want to take a look at the PAVs that are run by a small computer that monitors temperatures in your attic, meeting a set threshold, the fans will turn on and start to extract the humid air out of the roof.
Something else to seriously consider with these vents is they are often not only pulling air from outside through the soffits, but rather the conditioned air from within the home. Namely, through the light fixtures and attic access points, this somewhat hinders the ability to cool the interior of the house by the constant expelling of this air through your vents.
Found under the eaves of a roof, known as soffits. Installing vents here are integral to maintaining a healthy roof. Soffit vents are intake vents that allow dry air to be sucked up into your roof when paired with an exhaust vent. It is this perfect balance that maintains a healthy roof.
You must maintain a 50%/50% balance of intake and exhaust vents for optimal airflow through your roof. Thankfully you can install these vents all along with your soffits on both sides of your roof; you will need to ensure that you have the right amount of exhaust vents fixed on top.
How many roof vents do I need?
Across most residential building codes in the USA requires a minimum of 1 square foot of ventilation for every 300 square feet of attic. That being 1:300 with a vapor barrier, this is reduced to 1:150 if there is no vapor barrier present.
This calculation may vary depending on which state you reside in; you should check with a roofing professional in your area to make extra sure that your home is up to par with building regulations.
If you are trying to cover ventilation for 1500 square feet of attic, you would need at least 5 square feet of ventilation. Roofing ventilation must be split 50% intake and 50% exhaust to be effective at reducing moisture.
What type of roof vent is best?
The best roofing vent will vary from home to home, mostly based on the pitch of your roof. Most homes have a greater angle than 3/12. (roofs rising 3 inches for every 12 inches of its horizontal run.) These roofs are perfect for ridge vents paired with soffit vents.
In my opinion, these are the best sets of vents for your household due to the way they work. The ridge vent runs at the highest point of a roof and the soffit vents running the lowest, this is perfect for creating a steady stream of dry air running through your roof. It is this vacuum that protects your roof from hot and humid air building up in your attic as well as saves you money on energy bills.
These vents require little to no maintenance, putting them ahead of other ventilation systems. Where powered vents need energy to run and a yearly maintenance routine, ridge vents are made of hard plastic and require no moving parts.
Hi there! My name is Jonathan and I absolutely love writing DIY roofing guides. If you have any questions, I invite you to leave them below in the comment section and I will get back to you as soon as possible. If you enjoy my work, please follow me on social media or share this post on yours. All this information has been double checked for accuracy, but please let me know if I have missed anything!