When I re-roofed I had the roofer install a 4' ridge vent. There already were two conventional metal vents on each side of the ridge about a foot below the ridge which are spaced to either side of the new ridge vent. There are ample louvre vents in the eaves. Last winter I noticed condensation in the attic on the roof sheating and the trusses. The insulation is only about 4" deep on the attic floor. (I don't know if there was a moisture problem before I reroofed because I recently bought the house.) I read a newspaper column by James Dulley stating that if you have conventional roof vents and install a ridge vent, the inlet air will come in through the roof vents instead of the vents in the eaves, thus not passing over the insulation area. I would greatly appreciate your opinion and any suggestions you have to remedy my problem. Thanks, Paul.