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ceiling insulation and vapour barrier Post New Topic | Post Reply
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Sophie Kneisel
Posted: Aug 09, 2007 02:58 PM
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ceiling insulation and vapour barrier
I'm considering using 4 inches of (2 lb?) foam on the entire roof of my 150-year-old 1 1/2 storey house. The brick walls need work, so I plan to use two layers of polyiso rigid board on the walls. Do I need to insulate the ceiling as well (batts or blow-in would be used) so I'm not heating the whole attic space, or would this mean ventilation would be required? And should there be a vapour barrier installed on the inside of the foam?Thanks. |
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mason
Posted: Aug 09, 2007 03:38 PM
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A vapor retarder is not required with closed cell (2lb) sprayfoam. I wouldn't install insulation to the floor of the attic. Just be sure you spray the kneewalls and seal the attic. 4 inches of 2lb foam will provide enough insulation to sufficiently to provide good energy efficiency in most areas but check with local building codes for the amount required in your climate zone. |
