I'm buying a house in Colorado, and the house has a vaulted (cathedral) ceiling such that both the plywood sheathing and the ceiling sheetrock are attached to opposite sides of the rafters, i.e. no attic. My inspector said it needs ventilation (ridge vent + soffit vents). The roofer who did the job for the sellers says it does not. Does such a roof need venting? It's a passive solar home without a lot of cooling ability. My concern is heat buildup during the summer and potential moisture build-up. The roof is only 5 years old and one of the sheets of plywood has already blistered significantly.