Can I get away without a number of those layers provided my climate zone? For instance, can I use all Roxul, with out XPS? Do I Totally need to have the drywall?
The principle flaw With this roof appears to get the ice and h2o membrane at the highest stage from the rafter bays. Would just typical felt paper have authorized ample moisture to dissipate throughout the roof sheathing averting rot?, I form of question it.
A lot of my neighbors listed here have cathedral ceilings, no attics and Certainly no insulation (in essence they have aluzinc roofs on plywood with pine rafters).
The code limits on using air-permeable insulation between rafters have been created to stop the roof sheathing from rotting. When fiberglass batts are mounted in unvented rafter bays, the batts make it possible for moist indoor air to reach the cold roof sheathing.
Chuck- Google "reclaimed foam." There are a number of sellers of reclaimed foam in MA. You can help you save a bundle and enable the World in addition.
2. It looks like you will be using steel beams to body your hips. As I am confident you already know, these steel beams are thermal bridges. All insulation must be on the outside side from the steel.
Like Doug's layout, the main focus is on making a superior perm layer for drying to the outside, that could continue to allow for venting although blocking wind washing within the fluffy stuff.
You explain your proposed air barrier as "taped felt." I do not Assume asphalt felt may be successfully taped, and I do not believe asphalt felt would make an excellent air barrier.
Thorsten Chlupp is inside of a much more challenging local climate and he appears to be performing good with simple loose fill on the attic floor....of course He's utilizing "enough" amounts (cellulose galore)and he has baffles near the soffit.
"R-19 batts are really air permeable, and on extensive unobstructed rafter bays you may have pretty a stack result. It won't have a large degree of air leakage to deliver some drying there. Also, In the event the batts are unfaced or kraft-faced, the drying toward the interior additional reading can be sizeable.
Your approach to set up a stack of rigid foam rectangles in Just about every rafter bay is called the "Slash-and-cobble" way of insulation. It truly is a method generally picked out by homeowners, but never ever chosen by insulation contractors.
The wall and roof portion of those residences indicates that they are unvented assemblies. (However unclear to me how that is Safe and sound). I thought if I did basically precisely the same factor, but extra over-sheathing vent strips for steel roofing, I would be golden, but I think I'm lacking something right here.
So a hybrid tactic needs to be investigated. Dense packed see this cathedrals with warmside ridged foam to incorporate R, taped, no recessed lighting or other air paths after which belt and suspenders... Include venting Despite the fact that there isn't a usual 1" vent path.
two. Install sturdy website-constructed ventilation baffles in Every rafter bay before you decide to spray the foam. That way you end up having a vented cathedral ceiling.