Even though vented roof assemblies are intended to dry to the exterior, unvented roof assemblies are made to dry to the interior. That’s why an unvented roof assembly should really never involve interior polyethylene.
The perimeters of the roof are covered with asphalt shingled (GAF Slateline for being precise). It appears like I must pull down the fiberglass and also have it spray-foamed right before I drywall.
If you'd like to pick out a cloth that may be a little bit additional vapor-permeable on your air flow baffle, you are able to -- as an example, lots of people use slender plywood or fiberboard During this area -- but you really don't have to. The EPS will get the job done
Q. "If I install a polyethlene sheet concerning the bottom from the batting as well as sheetrock [It will be connected to the purlins], wouldn't this be an inside vapor barrier?"
I question the condensation is occurring in opposition to the chilly ridge beam. Relatively, I believe it is likely that condensation is going on around the underside of one's ridge shingles or perhaps the underside on the asphalt felt underlayment.
You're proposing a vented roof assembly. For any vented roof assembly, the code isn't going to involve that any foam insulation be put in direct contact with your roof sheathing -- Quite the opposite.
I employed to operate like a roofer, and roofs which might be totally included with Ice & H2o Protect make me nervous. I see such a design as lazy and perhaps problematic.
Will it make sense to spray and Minimize and cobble four inch closed cell foam/board on underside of sheathing accompanied by fiberglass inside the bays and 1 inch of eps/iso underneath the rafter (to stop thermal bridging) right before finishing with drywall? Will I make a vapor sandwich and superior go away the final EPS and settle for the thermal bridging?
Doug I concur, a lot of wrongs "overthinking" and overdoing. I after had to resupply a health care provider building an plane with dozens of AN aircraft bolts because they had been tightened to the point of breaking the bolts. A lot less is a lot more in some cases... Along with the KISS rule.
The correct way to proceed is to put in rigid foam earlier mentioned the roof sheathing. There really are not two responses to this problem. Time to try and do the work has become. If your contractor will never carry out the necessary perform, you'll need to hire a unique contractor.
Many thanks for finding the thread previously mentioned...Notice that in submit #17, Robert Riversong talks concerning the "vented in excess of roof". I concur along with you that this technique justifies some interest for cathedral ceilings.
I'm creating a click here for more info forensic laboratory constructed in Massachusetts, and am possessing a hard time reconciling relevant creating code with my go through of the literature pertaining to insulation and roof deck condensation.
As I explained during the report on this webpage, You can not use fluffy (air-permeable) insulation in an unvented roof assembly Until you incorporate rigid foam or spray foam over the fluffy insulation.
Many spray foam roofing contractors within our current market are touting their skill strengthen efficiency on outdated sizzling tar and graveled flat roofs by introducing three to 4 inches of shut mobile spray foam. Most of these previous residences are flat roofs joisted with dimensional lumber, with parapets and possess stucco vents Minimize into the rim joists.