Effective ventilation in an unfinished attic usually includes intake vents down low along the soffits, and exhaust vents up high at the peak or roof ridge. This allows for a continuous flow of air through the space.
Your roof vents should be split evenly with half dedicated to air intake and half dedicated for air exhaust. That means that a 2,400-square-foot home with a roof that has a moisture barrier would need 8 square feet of roof vent.
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.
Shingles get very hot and prematurely age when poor roof ventilation keeps the attic too warm. Ice dams are a sign of poor roof ventilation, and they cause damage to shingles and eaves. If left untreated, they can even cause roof leaks.
While ridge vents have many advantages, they are not always ideal. In cold climates, ridge vents can allow snow into the attic. They're also more expensive than box vents and won't work on all types of roofs.
The two main dangers associated with too much ventilation involve roof damage and increased utility bills. If you have too much air circulating, your roof will collect moisture causing damages that will weaken spots and then cause leaking.
Turbine roof vents are an effective and energy-efficient way to ventilate your roof. Unlike traditional ridge or soffit vents, turbine vents use wind power to spin a turbine fan on the roof, which in turn creates suction that pulls air from the attic.
These leaks can occur due to various reasons, including: Poor Installation: If roof tile vents are not installed correctly, gaps can form between the vent and the surrounding tiles, allowing water to seep through.
Measure the size of your attic
First, you'll want to consider the size of your attic. The larger the attic, the more vents you'll need to ensure proper ventilation. As a general rule, you should have at least one square foot (144 square inches) of ventilation for every 300 square feet of attic space.
Nails, shingles, and the old vent will need to be removed.
Static Vents
They are designed with louvers or slats that open outward to let warm air out but close when it rains to keep water out. Static vents promote proper airflow throughout the entire roof system, helping to prevent mold and moisture buildup which can cause damage over time.
For a home with 2000 square feet of attic floor space, you'll first divide 2000 by 300 (2000 ÷ 300 = 6.66). You need 6.66 square feet of attic ventilation. Since you want a balanced system, you divide by 2 so that half of the ventilation is intake and half is exhaust.
What Is the 1:300 Rule? The US Federal Housing Authority recommends a minimum of 1 square foot of attic ventilation for every 300 square feet of attic floor space, evenly split between intake and exhaust.
Effective ventilation in an unfinished attic usually includes intake vents down low along the soffits, and exhaust vents up high at the peak or roof ridge. This allows for a continuous flow of air through the space.
A Ridge Vent is a commonly used roof exhaust vent and should be installed along the entire roof's horizontal ridge. This creates a far better appearance by allowing it to blend into the roof's natural look. A roof Ridge Vent works by distributing hot and cold air, rather than creating hot and cold sections.
Today, most experts (and our team at Rhoden Roofing agrees), ridge vents are superior products to box vents. However, as they are more expensive to install than box vents, they still are not the vest fit for every situation. There is also more variety in the types of ridge vents.
Natural ventilation can generally provide a high ventilation rate more economically, due to the use of natural forces and large openings. Natural ventilation can be more energy efficient, particularly if heating is not required. Well-designed natural ventilation could be used to access higher levels of daylight.
A universally accepted guideline for roof ventilation is the 1/150 ventilation rule. According to this rule, a roof must have ventilation that is at least one square foot for every 150 square feet of attic or crawl space. A minimum of 13.3 square feet of ventilation is needed for a 2,000-square-foot attic.
Beyond the energy savings, roof ventilation can also prevent many issues, including mold growth, ice dams, and structural damage due to moisture in your attic.
Ridge vents are typically the experienced roofing contractor's top choice for a superior attic ventilation system. With turtle vents, roofers need one for every 150 square feet of attic floor space. With ridge vents, you only need one for every 300 square feet — their efficiency is double that of turtle vents.
In my experience, a mix of passive and active ventilation tends to work very well; combining an attic fan with ridge vents will improve what the natural process starts, which makes sure your attic remains healthy.
Look Out for Flashing
In this case, rain can enter your roof through the vents. As for damage to the vents themselves, old age is a factor. Eventually, certain areas of your roof may be worn down, including the flashing that supports ridge vents. You will likely be unable to predict when your flashing is going to fail.