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We’re getting ready to insulate the ceiling in my new home. The house was constructed with ICF’s. It has ridge vents and soffit vents. The builder has recommended blown in insulation because of the cost saving over bats. I asked him what do we do about a vapor barrier then, and he said in a ceiling it usually isn’t necessary. Isn’t it necessary to keep moisture out of the attic to protect the insulation value?
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Vapor barriers have nothing to do with insulation value, except in the sense that they might possibly prevent drafts. They are intended to prevent the moisture that is inside every home (showers, that boiling pot of noodles) from getting inside the wall cavities, condensing, and making your walls a very pleasant place for all kinds of unpleasant things to grow. A vapor barrier would be nice, but it isn't a necessity. Adequate attic ventilation above the insulation is infinitely more important in my opinion than ceiling vapor barriers.
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We're getting ready to insulate the ceiling in my new home. The house was constructed with ICF's. It has ridge vents and soffit vents. The builder has recommended blown in insulation because of the cost saving over bats. I asked him what do we do about a vapor barrier then, and he said in a ceiling it usually isn't necessary. Isn't it necessary to keep moisture out of the attic to protect the insulation value?