Having proper attic ventilation is key to a energy efficient home. For example, in the winter if no ventilation exists there will be no natural air to keep the attic cool and prevent what's known as ice damming, which is snow that melts off a certain area of the roof thats warm and then turns into ice near the gutters,
causing an ice dam which can damage the roof and can even cause leaks.
In the summer, an unvented attic traps hot air. This causes excessive heat build-up in the attic which can seep through the insulation on your ceiling and into the home envelope.
Note: This image is insulating the sheathing which is primarily used to insulate the attic for storage and other purposes where certain temperatures are required.
Energy Efficiency | Ventilation
When considering attic ventilation, it may seem unusual to see it discussed under energy efficiency. How can having any ventilation in your home cut down energy costs or make the living space more comfortable? The first thing to understand about ventilation systems is that the attic space is actually a seperate area to begin with. The area where people live in is known as "the envelope" and the air in the attic and within the envelope are seperated by the insulation laying right above your ceiling on the attic floor.
An attic without a proper ventilation system
How a ventilated attic works
There are two types of ventilation systems, a natural or passive ventilation system, and an active ventilation system. A natural/passive ventilation system consists and relies on two main components: a soffit vent and ridge vent. An active ventilation system also consists of a soffit but it also uses fans to further ventilate the air in the attic. Both ventilation systems rely on having an open soffit vents and that the home envelope remain well sealed from the attic space. Below you can see how passive ventilation system works.
Ridge Vent which acts as the exhaust of the air brought in by the soffit vent.
Soffit vent which serves as the intake of outside air
Baffles are placed in areas where insulation is accumulated the most. This will allow air from soffit vents to properly enter the attic space and then exit through the ridge vents
Active ventilation systems, equip a powered fan to enhance air ciruclation within the attic space. This image shows a cross ventilation system and is used for illustrative purposes only.
Though you are free to choose any ventilation system you desire. Our manufacturer, Certainteed, recommends that you stick to one ventilation system. By adhering to Certainteed's installation instructions you can be fully covered by Certainteed's SureStart warranty for any product defects at no charge.