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I’ve heard two schools of thought on vapor barriers and would like to get some clarification! I’ve always thought a vapor was necessary yet a Heating/AC guy told me that it’s better not to have one so the walls can breathe.
Our construction is exterior tongue-n-groove redwood with a latex solid stain, 2″ of foam board, and drywall. Do I put in a vapor barrier or not?
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...FredL... I can see why you don't want a positive pressure.. because you don't want to force moist warm air out of the envelope...
but why do you want a negative air pressure...don't you worry about sucking rain in thru the flashings, and around the windows and wetting your walls from the outside in...?
*Laura:This subject has used a lot of server space, time and even acrimony. The one thing that has become certain is that there are passionately held ideas that may or may not make any sense in your geographic area. Some ideas are just wrong in most any geographic area.So, to get some useful information to make up your own mind:-Search the archives.-Visit your local energy gurus. Some places you can look to find these folks are the Utility Company, local Cooperative Extension Service, Building Official, Low Income Energy Assistance Program Office or AGC office. Find out what works there and why.-Make your decision based on info from someone who has a personal stake on giving you correct information and if possible who has seen your building.-If you don't like what you are being told find someone for a second opinion.
*a good resource is the Southface Energy Institute located in Atlanta,GA. You will get more info than you need. Ask for mike barcik; 404 872-3549 or [email protected]
*Laura. It depends on your climate. If you are in a heating climate, yes. If you are in a mixed climate: both heating and cooling are necessary for significant periods of time, No. If you are in a hot humid climate an interior vapor diffusion retrder( VDR) is a NO NO. In this climate the VDR must be located on the exterior of the outside wall. Ckeck http://www.buildingscience.com. hope this helps. GeneL.
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I've heard two schools of thought on vapor barriers and would like to get some clarification! I've always thought a vapor was necessary yet a Heating/AC guy told me that it's better not to have one so the walls can breathe.
Our construction is exterior tongue-n-groove redwood with a latex solid stain, 2" of foam board, and drywall. Do I put in a vapor barrier or not?