To properly ventilate an attic, two types of vents are needed. Intake vents, which are located at the down slope edge of the roof (a.k.a. eaves) and allow fresh cooler air into the attic; and exhaust vents, which are located near or on the ridgeline of the roof and allow warmer air to leave the attic. The use of an exhaust vent in conjunction with an intake vent uses the natural forces of wind pressure and thermal effect, collectively known as the Stack Effect, to ventilate the attic space.
HINT: Make sure your attic insulation doesn’t block the intake vents. If necessary, use baffles to keep the insulation away from the intake vents.
There is also the problem of weather infiltration. Wind blowing across a roof surface creates negative air pressure. Nature will automatically try to compensate for it by moving air from a location of higher pressure, such as inside the attic. When the air is removed from the attic in this manner, it has to be replaced. If the proper intake ventilation isn’t used, air will be brought into the attic through the exhaust vents and will, at times, bring moisture with it.
If you suspect you may have poor roofing ventilation, contact Minnesota Building Contractors today. Call 507-206-9607 or submit a free roofing evaluation request.