As built, the attic of our 22-year-old house was ventilated with gable vents and soffit vents. We replaced the roof recently and added a ridge vent. According to the guy who writes the home-improvement column in the local paper, if you add a ridge vent, you should close off the gable vents, or the air pathway through the attic is short-circuited, flowing only from the gable vents to the ridge vent and not ventilating the lower part of the attic. The roofer said he thought this wasn’t necessary. Who is right?