A properly vented attic allows cool air to be drawn in through the soffit vents and hot and/or humid air to be exhausted out through the ridge vents or gable vents. Attic ventilation also flushes moisture out of the attic that has been carried up from the rooms below and protects the roof from rotting, freezing and ice dams.
Why Ventilation Is Needed
Proper attic ventilation is needed in the summer and the winter.
Summer
During the hot summer months, the air inside an attic that is not ventilated can reach temperatures of 150 degree Fahrenheit or more. When temperatures are this high in the attic, the attic insulation can gradually absorb the heat and pass it on to the cooler living space below. If the attic temperature is high, air conditioners must work extra hard to keep the living space cool. When this occurs, it is almost as if the attic had no insulation at all. The solution is to remove the heated air in the attic before it can build up. Good attic ventilation can reduce the temperature in the attic, and summer cooling bills.
Winter
Proper attic ventilation is just as important in the winter time as it is in the summer. Water vapor can diffuse through the ceiling into the attic. If the attic is poorly ventilated, the vapor can turn to frost on the rafters and the underside of the roof decking. As the weather warms up, the frost will melt onto the insulation. As the insulation gets wet, it loses its efficiency. If there is a large amount of water, damage can occur to the ceiling and walls below. Over time, there can be rot and other structural damage to the home. Vapor barriers are designed to protect the framing and insulation from moisture, but many homes either don’t have them or they are not properly installed.
An unvented attic also traps warm air and can cause snow to melt on the roof. The melted snow refreezes on the colder eaves of the roof causing ice dams which can damage the roof.
If you want more information or have any questions, please visit our website at www.apextx.com or view our YouTube Channel at http://www.youtube.com/user/ApexRoofingInc.
