Ideally there should be continuous soffit vents and a continuous ridge vent in your attic to allow for a passive air flow over the inside of your roof deck which prevents mold from forming in the winter. The old roofs just had a gable vent or two. Some have soffit vents but nothing at the ridge. Any of the the four types below the ridge on the image above would be fine. This static vent below is most common. Each roof is different but ideally these should be placed every six feet or so. Click here for roof venting calculator.
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