CA First, you should install proper vents against the under side of the sheathing from the soffit vents to the open space of the attic. Ventilation is crucial in today's well-insulated homes, helping to insure good indoor air quality. Also, this is the time to install a ridge vent if needed. Vapor barriers keep moisture from penetrating and condensing in the insulation. Be sure to seal every seam in the vapor barrier after insulating.
Moisture can penetrate through even the smallest gaps.
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