If you would like make an unvented insulated roof assembly, you have two possibilities: (a) You could incorporate rigid foam to the exterior side of your roof sheathing, accompanied by a second layer of roof sheathing and new roofing, or (b) You are able to insulate the underside of your roof sheathing with spray polyurethane foam.
(d) There might be enough air leakage with the "soffit" and ridge to deliver air move that functions the way a ventilation gap ordinarily would.
Builders remedy this issue by furring down or scabbing on added framing down below the rafters to deepen the rafter bays. A different technique is so as to add a layer of cross-hatched 2x4s, sixteen inches on center, put in beneath the rafters."
I have read too many stories of homeowners with problematic SIP roofs put in inside the 1980s -- some of these roofs are actually rotting on the seams because of condensation of moisture from exfiltrating interior air -- to truly feel at ease recommending a SIP roof.
If this had been my home, and If your fiberglass batts are seen, I'd personally pull each of the insulation out of some rafter bays to see what's up there.
The air leakage that Dana mentioned would maintain your roof dry, but would undermine its thermal effectiveness.
I thank you for this impeccably timed blog, as I am presently framing my semi-primary cathedral ceiling hip roof (with quick ridge). I wish to describe my element and check out to be familiar with the place I'm on the right observe and much more importantly, where by I will likely have failures. Hope I am able to amuse several of you...I feel such as far more I consider to address a priority, the more of a concern it becomes, And that i surely don't want to just take excellent time, treatment, and detail to aid the demise of my roof.
Many thanks - This can be new construction, I am the designer / builder, and the greater I examine it, I am liking all rigid - much less fussy. The best layer of rigid about fluffy makes my eave way too thick in any case. The air barrier to the T&G ceiling is really the sandwich of felt and taped 3/eight" CDX.
I now realize that stucco cannot be applied to a roof, so I will revert towards the a metal roof, but nevertheless want to obtain an unvented attic. I have read via "Creating a conditioned attic", and am continue to unsure regarding The ultimate way to proceed.
I'm executing the identical depth on my new construction. I bought the insulation from David Volpe @ NationwideFoam.com. There's a place in Framingham, MA. I bought various tractor trailer masses to insulate my household and barn for an exceptionally, incredibly acceptable selling price.
A. If the goal is to setup a fantastic air barrier, then drywall is undoubtedly adequate, as long as you seal all penetrations to prevent air leakage. For more on he said setting up drywall within an airtight manner, see Airtight Drywall.
On the topic of fluffy insulation, are there any sources you may refer me to which deal with the variances amongst very low, medium and superior density fiberglass batt insulation from the standpoint of lack of R-Benefit as a consequence of wind-wash (whether as a consequence of air infiltration or convection due to considerable temperature distinctions entrance to back again)?
Most creating codes have to have 1 square foot of Internet no cost ventilation area for every 300 go to this website sq. toes of attic ground place, assuming that 50 % in the ventilation openings can be found within the soffit, and 50 % alongside the ridge.
That you are proposing a vented roof assembly. For any vented roof assembly, the code isn't going to need that any foam insulation be placed in direct contact with your roof sheathing -- Quite the opposite.