Ventilating a roof requires making a path for air to move between the roof deck and the insulation. Natural (or passive) ventilation occurs when cool air enters the lower vents, is warmed, then rises and moves out the upper vents, exhausting hear and humidity.
Incoming Air
The most effective way for air to enter the roof is through vents that are placed in the soffits. Continuous soffit strip vents provide the most reliable port for intake air, while rectangular vents are the next on the list. Round ventilator plugs are easy to install, but usually are too small to provide adequate airflow. The important thing is to maintain at least 2 inches of clearance between the underside of the roof deck and all insulation. Insulation baffles ensure a clear pathway for air to travel between the rafters.
Outgoing Air
Stale air escapes through ridge vents at the peak of the roof, box-type vents near the top of the roof, or gable vents on the end walls. Continuous ridge vents are the preferred type for pitched roofs, while box-type gravity vents are best installed where ridge vents are not feasible, such as in a hip roof. For houses that have open attics and insulation attic floors, vents located in the gable ends may suffice if the openings are large enough. Gable vents also can be used in a finished attic above an insulation flat ceiling.
If you want more information or have any questions, please visit our website at www.apextx.com or view our YouTube Channel at http://www.youtube.com/user/ApexRoofingInc.
