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Cathedral Ceiling Post New Topic | Post Reply
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chad harris
Posted: Nov 01, 2011 08:00 AM
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Cathedral Ceiling
Mason, we have a customer that has a cathedral ceiling with 10'' studs. The customer is wondering if it is OK to put 3'' closed-cell in there, and have 7'' of dead air space totally sealed off. He seams leary of that and is thinking about soffits to ventilate that dead air space. This job is in South Texas and just wanted to see what you thought about it. Thanks.
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mason
Posted: Nov 01, 2011 08:12 AM
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There will be natural air infiltration through the drywall ceiling and the wall cavities so that space will not be completely air tight from the interior of the house. 3 inches of closed cell sprayfoam would be sufficient to separate inside and outside temperatures to prevent the potential for condensation so long as you have air sealed the attic from the outside air infiltration. Check out SPFA technical documents on unvented attics at sprayfoam.org and articles on attics and cathedral ceilings at buildingscience.com South Texas, ( I lived in South Padre Island for 7 years and still own a condo on the island) is typically a warm/hot/humid climate. The majority of the year, your air born moisture comes from outside. It would actually cause more potential for condensation to ventilate that space below the foam. Not only that but it would reduce the energy savings of the foam by allowing hot air into the living space. Not a good idea!!! |
