Are ridge vents required by building code?
What the code actually requires
Under IRC Section R806, a vented attic needs net free ventilating area equal to at least 1/150 of the attic floor area. That can drop to 1/300 when 40 to 50 percent of the required area is provided by vents in the upper portion of the attic, no more than 3 feet below the ridge measured vertically, with the rest low in the attic at the eaves. A vapor retarder condition also applies in the coldest climate zones, which do not include Georgia. The code does not say which product provides the upper venting: a ridge vent, box vents, or other high vents can all count.
Other rules around vents
- Openings must be protected against rain and snow, with screening or similar material.
- Insulation cannot block the eave vents, and the code calls for at least a 1 inch air space between insulation and the roof sheathing at the vent.
- Vents must be installed per the manufacturer's instructions.
- An unvented attic is allowed if it meets the specific conditions in R806.5, usually with spray foam directly under the roof deck.
Where "required" really comes from
Shingle manufacturers expect adequate ventilation for their warranties, and some enhanced warranties require the manufacturer's own ridge vent or other qualifying accessories. Your local Georgia building department enforces the code edition and amendments it has adopted, so a permit inspection may look at ventilation on a reroof. Read roofing permits in Georgia and roofing warranties explained for how those pieces fit together.