Roof ventilation
Airflow through the attic — intake low, exhaust high — that keeps a roof healthy.
Roof ventilation is the balanced flow of air through your attic: cool air enters low at the [soffit](/glossary/soffit) vents and hot, moist air exhausts high at the ridge or [gable vents](/glossary/gable-vent). It matters more than most homeowners realize. In summer, good ventilation carries away the heat that would otherwise bake the shingles from below and shorten their life; in winter, it removes moist air before it condenses into mold or feeds [ice dams](/glossary/ice-dam). A common code target is one square foot of net free vent area for every 150 square feet of attic floor. Blocked soffits or insulation jammed against the eaves quietly defeat the whole system.