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I’m about to build a Cape Cod and it would be great to just totally insulate the space between the ceiling and roof deck. I could get by with smaller rafters. I’m not at all concerned about roof warrantees. I don’t believe the surface temperature of shingles would be significantly lower if a roof is vented. What does concern me is moisture build-up. I do intend to use a poly vapor barrier, but even then some moisture could get into the space. I did a roof replacement about 15 years ago on a house with cathedral ceilings over half the house. The 1/2 inch plywood sheathing was so rotted over the cathedral spaces we ended up replacing a good portion. When we pulled the sheets up they were dripping wet with condensation and the insulation was soaked. Obviously there was little or no vapor barrier but even the best of vapor barriers can have some leaky areas. What are your thoughts?
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I'm about to build a Cape Cod and it would be great to just totally insulate the space between the ceiling and roof deck. I could get by with smaller rafters. I'm not at all concerned about roof warrantees. I don't believe the surface temperature of shingles would be significantly lower if a roof is vented. What does concern me is moisture build-up. I do intend to use a poly vapor barrier, but even then some moisture could get into the space. I did a roof replacement about 15 years ago on a house with cathedral ceilings over half the house. The 1/2 inch plywood sheathing was so rotted over the cathedral spaces we ended up replacing a good portion. When we pulled the sheets up they were dripping wet with condensation and the insulation was soaked. Obviously there was little or no vapor barrier but even the best of vapor barriers can have some leaky areas. What are your thoughts?