Attic Ventilation Theory

Intake vents located at the lowest part of the roof under the eaves allow cool.

Attic ventilation theory.

An attic fan can be gable mounted or roof mounted. In simplest terms attic ventilation is a process of creating air movement and circulation in the attic space. Having attic ventilation doesn t ensure the moisture gets ventilated away before it condenses on your expensive roof and wall surfaces. In a balanced ventilation configuration ambient outside air enters into the attic space via soffit or eave vents.

The intent of roof venting varies depending on climate but it is the same if you re venting the entire attic or if you re venting only the roof deck. A thermostat is used to automatically turn the fan off and on while sometimes a manual switch is used. This air passes through the attic space where it displaces warm moisture laden air which in turn exits the attic via vents at or near the top of the space being vented. In mixed climates ventilation serves either role depending on the season.

Here are some of the myths and the facts you need to know about attic ventilation. The theory behind attic ventilation is to give that moisture a place to escape before it causes mold mildew rot or other problems. Heat in the attic can roast shingles from below causing them to wear prematurely. Just like properly sizing your furnace and air conditioning unit you want precisely the right amount of attic ventilation for your home.

More attic ventilation is good. In a hot climate the primary purpose of ventilation is to expel solar heated hot air from the attic or roof to reduce the building s cooling load and to relieve the strain on air conditioning systems. While there are different product options available the process is typically done with a source of intake air fresh air normally drawn from the soffit or near the eaves and a source of exhaust typically near or at the roof s peak. It s believed that good ventilation in the attic will help prolong the life of shingles by reducing heat which maintains the shingles quality and durability.

Ice dams form when a home s escaping heat warms the roof sheathing and melts the underside of the snow layer on the roof. Another important element of attic ventilation is protection for the roof s shingle. Insufficient ventilation can lead to moisture problems during the winter and decreased energy efficiency during the summer but too much ventilation can be just as bad if not worse. The problem with this design is it is wishful thinking.