Hot And Vented Roof

Intake vents located at the lowest part of the roof under.

Hot and vented roof.

Cool air in hot air out attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Ventilation benefits a roof when it s hot outside as well. In mixed climates ventilation serves either role depending on the season. 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.

In colder climates the main purpose of a vented roof is to keep the roof cold and reduce the formation of ice dams. Vented roofs serve a number of different purposes and their roles vary from climate to climate. Also see insulation location for cathedral ceilings for more information. Traditional roofs employing asphalt shingles vented attics and insulation on the floor of the attic can get extremelyhot with surface roofing temperatures reaching up to 190 f during the summer.

Basically the term cold roof refers to a traditional roof or vented roof while hot roof refers to a roof that is not ventilated and which has foam insulation attached directly to the roof sheathing. A secondary goal is to vent moisture that infiltrates the attic from the conditioned home. Unfortunately the term hot roof is a misnomer as the roof really is not that much hotter than a normal roof. Good roof ventilation can do this but shingle color sun exposure and insulation are exponentially more important to overall energy efficiency than ventilation.

This can easily create attic temperatures as high as 125 f. In hot climates the roof temperature will be much higher on an un vented roof resulting in much shorter shingle life. This is less of a concern for slate and similar product roofs. A hot roof is one where there is no ventilation required as the insulation is directly attached to the roof sheathing.

When the temperature outside rises the temperature on your roof can be nearly double. The theory behind a hot roof system is that rather than allowing heat to escape through your roof you contain it in your attic space which can save on utility costs in theory. The hotter an attic is the more expensive it is to cool the upstairs of a home.