Do I need soffit vents with a ridge vent?
What a ridge vent does without intake
Wind passing over the external baffle creates suction at the ridge. With no low openings to feed it, that suction pulls air through whatever gaps exist: ceiling penetrations, the attic hatch and duct leaks. On gusty days, one side of the vent can even act as intake, which raises the chance of wind-driven rain getting in.
What manufacturers expect
Ridge vent and shingle manufacturers write balanced ventilation into their installation instructions, and the shingle warranty can depend on meeting their ventilation requirements. A ridge vent on an attic with blocked or missing soffit intake is one of the most common ventilation findings on Georgia reroofs.
Homes without usable soffits
- Short or no overhangs: an edge intake vent installed under the first shingle courses, above the drip edge, brings air in at the bottom of the roof.
- Boxed soffits with no vents: cut in vents and open the wood behind them.
- Soffits that are vented but blocked: baffles and cleared insulation restore the path.
What not to do
Do not leave gable vents open to stand in for intake. They sit high, so the ridge vent pulls air from them instead of from the eaves, and the lower half of the attic stays stagnant. Close them from inside when the ridge vent goes in, unless your roofer's calculation says otherwise.
For the numbers, see roof ventilation basics and ridge vent vs box vents.