Best Practices Attic Ventilation

Drive nails up through the sheathing and.

Best practices attic ventilation.

The recommended ventilation ratio to provide for vented attic assemblies when an air barrier is present is the 1 300 ratio as specified by most building codes. These vents allow outside air to enter the attic at the lowest point of the roof along the underside of the eave. 1 300 ventilation ratio recommended. How to install roof vents.

Ventilation helps even more when used in combination with radiant barriers. The average family of four generates 2 to 4 gallons of water vapor a day through activities such as cooking cleaning showering laundry and breathing. If your home is fitted solely with small gable end vents or a ventilator high in the roof you might want to consider adding soffit vents to increase airflow. For both attics and cathedral ceilings roof ventilation works best when it is balanced between high and low to take advantage of natural convection figure 2 55 at left.

Cut the shingles for roof vents. Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall. Cut the hole for roof vents. Adapted paraphrased with permission from best practices guide to residential construction chapter on best roofing practices.

This configuration also tends to evenly wash the entire underside of the roof surface with ventilation air. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic. From the roof s peak. Hot air exhaust vents located at the peak of the roof allow hot air to escape.

Attic ventilation can help remove the water vapor safely. The international residential code irc provision for attic ventilation requires a ratio of one square foot of net free open ventilation area for every 150 to 300 square feet of attic square footage. Center nails between rafters 18 in.