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Unvented Attic with Insulation Above Drywall Ceiling

albertoarriaga33 | Posted in General Questions on


Im in a tropical climate (northern Honduras), and wanted a second opinion on this type of assembly. 

This is a sheathing-less roof assembly that is completely vapor open but air tight. Attached is an image to give an idea. 

Assembly from top to bottom: Metal panels -> vented batten and counter-batten rainscreen -> solitex mento sarking membrane -> timber framing -> attic space -> blown in cellulose over drywall.

Any red flags? Anything that can be done better? On conceptual basis this is the most cost effective “high performance” assembly that our clients can afford. We cannot rely on mechanical conditioning of the attic because of power outages and unreliable occupant behavior. Therefore having a vapor open assembly and no condensation plane (sheathing-less) seems to be the most reasonable path.


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