Proper ventilation at the roof is important to a complete attic ventilation system as well as to the structural integrity of the roof. There are two basic categories of roof vents including passive and powered. A roofing contractor can install four different kinds of roof vents that all fall into one of the two categories.
All roof vents work by allowing outside air that enters the attic through the soffits to escape out the top of the roof, creating attic ventilation that carries away moisture and condensation before it has any chance to damage the structure of the roof, the insulation or the home.
Below are the four different types of roof vents along with some pros and cons. Your roofing contractor can help you decide which type of vent will work best for your roof and why installing the proper roof vent system can impact the structural integrity of your home over time.
Passive Roof Vents
Low Profile Roof Vents
|Low-Profile or Louvered Roof Vent|
The most common type of roof vent is probably the low profile roof vent. Also referred to as “louvered vents” these vents have a low profile and feature a slant-back design to guard against weather infiltration especially in steep-slope applications. They often available in either aluminum or galvanized steel and can provide between 50 and 60 square inches of net free ventilating are (NFA) per vent. Installation is relatively easy as most include pre-drilled holes for nailing.
Multiple low profile roof vents must be installed on the roof according to the square foot size of the attic. Under 1,000 square feet of attic space requires only 4 vents while a 3000 square foot attic can require as many as 12.
The low profile vent is usually installed on the back roof to minimize any unsightly appearance they may cause. The color of the vent can often be matched to the color of the roof depending on the manufacturer that is chosen.
|Ridge Vent At The Peak Of The Roof|
Ridge vents run the entire length of the roof peak and look very much like the shingles on the roof. These vents can offer several advantages over the low profile roof vents. First, they blend into the roofline creating a more attractive appearance overall and second, they achieve a balanced air flow that other types of vents just cannot deliver. Ridge vents, like louvered vents, are made to allow nothing but air to flow through them, so birds and insects are kept outside.
Roof Turbine Vents
|Turbine Roof Vent or Attic Exhaust Fan|
Also called metal pot vents or roof exhaust fans, the turbine vent offers a few key advantages under the right circumstances. Because they are so large and include rotating fan blades, they can remove huge amounts of air through the attic when wind is present. With as little as 5 miles per hour of wind the turbine vent can remove 347 cubic fee of air per minute from the attic. The results are even more impressive when wind speed increases.
Because the air flow can be so strong, it is especially important that soffits are kept clear of attic insulation to allow the same amount of air that is entering the attic that is being expelled. Otherwise the turbine vent will pull air from the interior of the home which can be a waste if it has already been heated or cooled.
Not all turbines will fit all roof pitches, so this option may not be feasible depending on your roof construction. Always be sure to install an aluminum turbine to prevent rust and make sure the ball bearings are permanently lubricated and sealed. The last thing you want is a squeaky roof turbine keeping you awake at night.
Active Roof Vents
Electric and Solar-Powere Roof Vents
Power vents on the roof can provide additional benefits to the homeowner as they help save on energy bills. These vents can quickly expel built up hot air in the attic that lingers in summertime making the cooling system work less to cool the house down. On the downside the electric powered models can defeat the purpose of decreasing energy usage as they operate using electricity. In a power outage they will not work at all. Solar-powered varieties exist that rely only on Mother Nature for their power.
There is some controversy however on the effectiveness of the powered attic ventilator. Unless you have a perfectly sealed ceiling, the air-pulling force of the power vent can be so strong that it pulls air conditioned or heated air right from your house. If you do in fact have a tightly sealed ceiling, then the power vents may not even be needed in theory because the hot air in the attic will likely not impact the cooling of the air in the home.
The best decision you can make is to speak directly with a reputable roofing contractor in your area about the best type of roof vent that they would recommend. As always, adequate ventilation in the attic is key to maintaining the integrity of both the roof and the interior of the home. Cold winter temperatures can post just as much of a threat as the heat of the summer, so year-round ventilation is critical.