My roof was replaced Summer 2010, Chicago suburbs. The roofer replaced the original Alum. ridge vent w/Cobra Vent. The next week we had a BIG storm & I had water stains on my drywall ceiling around the attic scuttle, 2nd floor.
Worse- in Jan.2011 I started getting lots of water stains on the ceiling, most along the outside wall & ceiling line on the north side. I went up in the attic & found heavy frost on sheathing & then condensation dripping off the nails. Also mildew on the roof sheathing. Never had any problems in 20 years with original vents, but since the roof job, I've got all these issues. Insulation, soffit vents & chutes all unchanged. Anyone else experience similar issues? If so, did you get it resolved?
Call your roofer. I doubt the leaks had anything to do with the type of vent, but more likely the workmanship.