A. You ought to only use an installation system that the insulation contractor is familiar with. Below from the Northeast, lots of contractors would most likely fill your rafter bays using the dense-pack method right after your new roof sheathing was installed.
Nevertheless, in some parts of the country, especially in the Northeast, insulation contractors are actually dense-packing unvented rafter bays with cellulose For some time. As the approach has deep roots in New England, numerous constructing inspectors acknowledge these kinds of installations.
Are you currently considering the 'flat' vented cavities will never give the assembly by having an exhaust path for dampness?
one. You don't need an interior vapor barrier. Within a incredibly hot humid local weather, the vapor generate is often from the outside toward the interior (assuming your developing is air conditioned). In case your creating is not ever destined to be air conditioned, the vapor drive will nonetheless be from the outside to the inside, but there won't be Substantially vapor travel.
one. It's always a nasty concept to set up an HRV within an attic. HRVs should be available plenty of for that homeowners to routinely alter the filter.
The air leakage that Dana pointed out would maintain your roof dry, but would undermine its thermal effectiveness.
  He graduated from Collinsville Highschool in 1941, and managed to Reside extensive more than enough to show up at his 75th course reunion in the fall of 2016 – when he picked up two of his classmates from nursing houses and drove them on the reunion. He was inducted into the Army in 1943, turning into a sergeant while in the Signal Corps through Entire world War II. He fought in France and Germany, and was within the Philippines planning for an invasion of Japan once the war finished, then served Along with the occupying forces in Japan.
Like most mansard roofs, your roof is unvented. Your mansard roof has distinctive sections -- the steep sections within the perimeter, as well as the very low-slope segment in the middle. All of these sections have to be insulated in the same way, because all of these roof assemblies are unvented.
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Second, could you please confirm this: "If you want to use only one type of insulation in unvented rafter bays, that you are restricted to spray polyurethane foam."
You wrote, "the rafters are still exposed," but I'm unsure Whatever you necessarily mean by that. Do you've kraft-faced batts among the rafters, While using next page the kraft going through however seen?
Could you make sure you supply a depth of higher than sheathing air flow using a steady Ice&Water membrane, and metallic roofing for the blended weather? Thanks
Very well the roof is happening with the very first layer of insulation (on-prime the purlins, under the roof sheeting). There seems for being adequate House left during the four" purlin cavity for the second layer of R11 to be installed without any modification.
You say "You do not need an inside vapor barrier," but Additionally you say that "You'll need a fantastic air barrier on either side of your respective fiberglass batts." The latter would develop into an inside vapor barrier not so?