I live in the rainy region of western Washington. I own a 4-bedroom rambler that I bought in 2002. It has a two-car garage. The pitch of the roof is really low, like about six-to-one. A roofing company replaced the roof in 2006, with a standing-seam metal roof. They installed new sheathing. The workmanship looked good. This morning it was probably around 30 degrees, and snowing lightly. I looked up at the ceiling in the garage, and there were wet areas on the plywood. There was a wet streak more or less parallel to one of the rafters, as well as other wet areas. Is there a way to be sure whether it is leaking? In case it makes any difference, the garage has a ventilated cap at the peak. I keep the garage window open about an inch to give some ventilation. How should I proceed on this?