Unvented Attic in a Hot Humid Climate

Guest User
9/18/2017
I am in the planning stages for a post framed house with metal roofing and siding. I have been reading up on the topic of building science, but have not found answers to my questions. Joseph Lstiburek has a paper called "The Top Ten Dumb Things To Do In The South". In it he recommends not venting the attic space, and placing the HVAC into the conditioned area of the home. So my question is what would be proper roof assemblies that would work in my climate zone(edge of 2A and 3A). The roof will be a 6/12 pitch,3/4" ribbed metal panel over a single bubble foil insulation(for condensation control) screwed to purlins. What I am looking for is the proper way to use blown in fiberglass in between the purlins. I see Owens Corning has a Boxed netting system that would allow up to a 12.25" cavity depth attached to 2x6 purlins for use in the dryer 2B and 3B climate zones. Would adding a vapor permeable product at the ridge of the house allow the Boxed netting system to work in my climate zone? The conditioned attic would hold the HVAC system, and any leakage would be into the conditioned environment, not to the outside environment.
Eric Novotny
An informed customer is the Best Customer!
9/19/2017
You cannot and should not put blown in insulation in a sealed attic design and definitely not above deck. http://www.finehomebuilding.com/pdf/021221068.pdf
Guest User
9/19/2017
According to the above article, if I sprayed an R-5 layer of closed cell foam under the single bubble layer foil, I could then insulate the rest of my required R- value with blown in fiberglass (flash-fill). Does anybody know where to buy "Boxed Netting"?
Eric Novotny
An informed customer is the Best Customer!
9/19/2017
Most insulation supply houses have the insul-web products. It will be cheaper for you to incorporate rigid foam that is above deck than spraying closed cell foam.

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