Best Practices Attic Ventilation

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.

Best practices attic ventilation.

Cut the hole for roof vents. 1 300 ventilation ratio recommended. 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. This configuration also tends to evenly wash the entire underside of the roof surface with ventilation air.

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. How to install roof vents. Cut the shingles for roof vents. 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.

Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic. Mark attic roof air vent locations. Ventilation helps even more when used in combination with radiant barriers.

Attic ventilation can help remove the water vapor safely. Center nails between rafters 18 in. Hot air exhaust vents located at the peak of the roof allow hot air to escape. 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.

These vents allow outside air to enter the attic at the lowest point of the roof along the underside of the eave. Drive nails up through the sheathing and. From the roof s peak.