Best Practices Attic Ventilation

Center nails between rafters 18 in.

Best practices attic ventilation.

These vents allow outside air to enter the attic at the lowest point of the roof along the underside of the eave. This configuration also tends to evenly wash the entire underside of the roof surface with ventilation air. Ventilation helps even more when used in combination with radiant barriers. Experts recommend using attic ventilation in hot climates as part of an overall strategy to reduce cooling loads.

Hot air exhaust vents located at the peak of the roof allow hot air to escape. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic. Adapted paraphrased with permission from best practices guide to residential construction chapter on best roofing practices. Additionally attic ventilation is a key ingredient in the defense against ice dams in snow and ice climates.

1 300 ventilation ratio recommended. 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. Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall. Drive nails up through the sheathing and.

Cut the shingles for roof vents. 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. Cut the hole for roof vents. From the roof s peak.

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. How to install roof vents. Attic ventilation can help remove the water vapor safely.