ARMA’s Guidance for Attic Ventilation
Proper ventilation of attic areas is an essential factor in realizing the maximum service life of the building materials used in the roof assembly. Overlooking proper ventilation may result in:
- Premature failure of the roofing including blistering
- Moisture accumulation in insulation and other roof system components
- Mold growth and rotting of wood components
- Roof deck distortion that can cause buckling of the roofing
- Ice dam formation in cold climates
Ventilation and Design Considerations.
A best practice is to create an approximately balanced combination of intake and exhaust vents to generate optimal free-flow ventilation.
Ventilation and Moisture Control.
Proper attic ventilation can remove water vapor from the attic space before condensation can occur.
Ventilation and Heating & Cooling Costs.
A properly ventilated flow-through air space beneath the roof deck and above the insulation can significantly reduce heat buildup in the attic.
Ventilation and Ice Dams.
Proper ventilation can reduce the likelihood of the snow melting (unevenly) by keeping the entire roof deck at a more uniformly cold temperature, thus helping to prevent ice dam formation.
NOTE: From Residential Asphalt Roofing Manual: Design and Application Methods – 2022 Edition