Do I need roof vents in a garage?
Short answer. If the garage has a ceiling with an enclosed attic above it, yes, the residential code treats that attic like any other and requires ventilation sized to its floor area. A garage with open rafters and no ceiling is not an enclosed attic, but venting still helps release heat and moisture under the roof deck.
Four common garage setups
- Attached garage sharing the house attic: the garage attic is part of the same space, so its floor area counts in the total and its eaves add intake. Ridge vent usually runs over both.
- Attached garage separated by a fire wall: the wall divides the attic into separate spaces. Each one needs its own intake and exhaust, so the garage attic cannot borrow from the house.
- Detached garage with a ceiling: its attic needs ventilation on its own, typically soffit intake and ridge or gable exhaust.
- Open rafter garage: the underside of the deck is exposed to the garage. No attic vent rules apply, but heat builds under the roof, and in Georgia humidity a closed garage with a car dripping rainwater can form condensation on the deck.
Bonus rooms over garages
A finished room over the garage often has sloped ceilings with knee wall attics on the sides. Those side attics and the rafter bays over the sloped ceiling need vent paths, and they are a frequent source of hot bonus rooms and moisture problems.
What a garage attic needs
- Intake at the eaves with baffles if insulation is present.
- Exhaust at the ridge or high on the roof.
- Net free area based on the garage attic's floor area.
A roof replacement is the natural time to add ridge vent and intake to a garage. See roof ventilation basics and ridge vent vs box vents.