Proper Ventilation for Your Roof

For years, manufacturers of various roofing products have often blamed a roof’s failure, if it does indeed fail, on the lack of proper ventilation.

So, what is proper ventilation?

Ventilation is measured in NFI (net free inches) of ventilation.

The main purpose, surprisingly enough for ventilation is not cooling, but rather, drying. When you attain adequate air movement, you greatly lessen the chance for mold and mildew formation; mold and mildew flourish in moist environments.

Secondly, of course, comes cooling. As the sun heats the air, and the hot air has little, or no chance to escape, it can actually “wick” downward, trapping the heat, permeating the ceiling, and causing higher temperatures inside the structure.

To attain proper ventilation, it is necessary to view it in two parts, the first of which is exhaust. Exhaust is created when warmer air rises, then through either turbine, gable, or dormer vents, and more recently ridge vents, that same air is allowed to escape.

Exhaust is good, but in order to attain optimum ventilation, attention must be given to intake ventilation which is created at the bottom of the slope, by either “bird holes” drilled above the baring wall, thru the fire block, or low profile roof vents, which are a manufactured product and which are installed at the bottom of the slopes, again above the baring wall.

Intake ventilation is crucial. Ideally, the net free inches of intake to exhaust ventilation should be about equal. If, however, for various reasons, that is not possible, the intake, rather than the exhaust, is the more important of the two.

Although, as roofing contractors, we are not scientists, most of us would agree that there is validity to the science. Our goal is that, when a question does arise, Raneri and Long will be your trusted source for information.