Quick Vapor Barrier Question

Quick Vapor Barrier Question

Postby anonymous283 » Wed Dec 19, 2018 10:00 am

In every other study material I am told to put the vapor barrier on the warm side of insulation. The only exception is ncarbs 4.0 BDCS question 9 attached below. I answered C. They say to put the barrier between 2 pieces of sheeting - why?
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Re: Quick Vapor Barrier Question

Postby kkriegs » Sat Dec 22, 2018 3:07 pm

You put a vapor barrier on a rigid surface, not directly on the insulation. So, the sheathing would be secured on the outside of the insulation and would serve as a rigid surface to which you can then adhere the vapor barrier.
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Re: Quick Vapor Barrier Question

Postby greek22 » Wed Dec 26, 2018 7:50 pm

You would primarily put the vapor barrier on the warm side of the insulation in a COLD climate. The question states "HOT, HUMID" climate though.
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Re: Quick Vapor Barrier Question

Postby jfmonod » Wed Jan 09, 2019 7:04 pm

It’s D because thats the closest location to the warm side. I’m in Florida. It’s typically 20 degrees warmer outside than inside. Here, you always want the vapor barrier as close to the outside as possible. With stucco buildings the exterior paint becomes the vapor barrier. You want to stop the moisture at its source.
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Re: Quick Vapor Barrier Question

Postby Raja » Fri Jan 11, 2019 10:33 pm

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Re: Quick Vapor Barrier Question

Postby ablumetti » Mon Mar 11, 2019 12:29 pm

depends on the region...cold northern would be A because moisture travels from hot to cold...would have to pass through insulation in northern climate and soak it. In south the opposite is true. Moisture would go from outside to inside.
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