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Vapor Barrier For Open Cell Post New Topic | Post Reply
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KZybert
Posted: Jun 08, 2017 06:28 PM
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Vapor Barrier For Open Cell
I am deciding between open and closed cell spray foam throughout my whole house. It is my understanding that with open cell I need a primer that is also a vapor barrier. Primers that advertise their vapor barrier are around $250 for a 5 gallon bucket--making closed cell more economical for me. The question is, would an oil based primer serve as a sufficient vapor barrier? I cannot find any information on the permeability of oil based primer. I am in the Buffalo, NY area if that helps with the answer. Thanks in advance, Kevin |
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mason
Posted: Jun 08, 2017 06:53 PM
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Kevin, The vapor retarder coating would go over the foam not on the substrate. Each coating manufacturer publishes a data sheet that lists the permeance of the coating typically at 20 dry mils. Check out the permeance, it should be less than 1 perm to qualify as a vapor retarder. Some of the intumescent coatings we use over foam for fire resistance might qualify. Ask your foam supplier for their recommendations. |
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KZybert
Posted: Jun 08, 2017 08:33 PM
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Ok, thank you very much |
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polyol
Posted: Jul 13, 2017 06:54 PM
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In many ways you want open cell to breath, but if you need a vapor barrier you will have to coat it or spray it with something that is qualified. |
