Attic Ventilation Theory

A thermostat is used to automatically turn the fan off and on while sometimes a manual switch is used.

Attic ventilation theory. More attic ventilation is good. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Several purposes of an attic ventilation system are to provide added comfort to help protect against damage to materials and structure and to help reduce energy consumption during all four seasons of the year. The problem with this design is it is wishful thinking.

In mixed climates ventilation serves either role depending on the season. An attic fan can be gable mounted or roof mounted. 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. In a balanced ventilation configuration ambient outside air enters into the attic space via soffit or eave vents.

Having attic ventilation doesn t ensure the moisture gets ventilated away before it condenses on your expensive roof and wall surfaces. Ice dams form when a home s escaping heat warms the roof sheathing and melts the underside of the snow layer on the roof. 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. 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.

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. Heat in the attic can roast shingles from below causing them to wear prematurely. 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. A powered attic ventilator or attic fan is a ventilation fan which regulates the heat level of a building s attic by exhausting hot air.

Here are some of the myths and the facts you need to know about attic ventilation. 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. Another important element of attic ventilation is protection for the roof s shingle. The theory behind attic ventilation is to give that moisture a place to escape before it causes mold mildew rot or other problems.