What does proper roof venting and attic ventilation look like?
Short answer. Proper roof venting is a balanced system: air enters low at the soffits or eaves, travels up under the roof deck, and leaves high at the ridge, with intake at least equal to exhaust and only one type of exhaust vent serving a shared attic. Total net free area should meet the code ratio of 1/150 of the attic floor, or 1/300 when the system is balanced.
Walk the airflow path
- At the eaves: continuous soffit vents or evenly spaced rectangular vents, clean and unpainted, with openings cut through any old wood soffit behind vinyl panels.
- Above the wall: a baffle in each rafter bay that has an intake vent, keeping at least a 1 inch air channel between insulation and the deck.
- Across the attic: nothing blocking the path, and no bath fan ducts ending loose in the attic.
- At the ridge: a single exhaust system, usually a continuous ridge vent over a properly cut slot, or static vents grouped near the peak when the ridge is too short.
- At the attic floor: air sealing around recessed lights, top plates, plumbing chases and the hatch, so house air does not feed moisture into the attic.
Signs it is working
On a hot afternoon the attic is hot but not oven-like, the underside of the deck is evenly light colored, nail tips are clean, insulation is dry and fluffy, and no single room runs much hotter than the rest of the house. In winter there is no frost on the nails after a cold snap.
What does not count as proper
A ridge vent plus gable vents plus a power fan is three exhaust strategies fighting each other. A roof full of vents with no soffit intake can only pull conditioned air out of the house. More vents is not the same as better ventilation; balance is the goal.
Read roof ventilation basics for the theory and heat, humidity and roof life for why Georgia attics need it.