Slash-and-cobble is definitely an insulation strategy used by some homeowners, but in no way by insulation contractors. It includes slicing rigid insulation into slender rectangles, and inserting the rectangles among rafters or studs.
My sense is usually that if we are concerned about air leakage compromising the insulation's success, vent channels are problematic.
You need to consult an electrician about the best way to provide your ceiling electrical boxes. There are lots of probable alternatives -- some visible from the inside, and a few hidden by the new foam.
The R worth of your Minimize'n'cobbled foam + exterior foam should be a minimum of 40% of the middle-cavity R worth for dew point control in the foam/fiber boundary in zone 5. If It truly is arising a bit shy of that ahead of including the exterior foam it is not a giant offer inside the short term, but when it will be five-ten years right before re-roofing to lift the foam-R to above forty% of the whole It really is well worth employing vapor barrier latex primer around the gypsum board, or a smart vapor retarder in between the gypsum board & fiberglass.
Since I have stated the right way to get it done, I will even Allow you to realize that Many individuals have finished Anything you suggest.
The for a longer time that you choose to wait to setup rigid foam higher than your roof sheathing immediately after your click here for more info rafter bays are filled with fluffy insulation, the increased the risk that the roof sheathing will accumulate humidity. A few a long time must be no challenge, but I would not stretch the exercise much farther than that.
Are you aware the initial supply for this Photograph and if it can be done to view other photographs of this fascinating failure.
Your want to use 2-inch-thick EPS as your ventilation baffle will get the job done. The EPS is rather vapor-permeable, so it allows a small amount of outward drying. (In any circumstance, for read review those who build a reasonably airtight ceiling, there won't be any moisture Within this assembly that should escape.)
I are already employing rigid breadboard fashion expanded polystyrene inside the rim joists and imagined a similar could be put under the sheathing amongst the rafter bays, and with any gaps sealed which has a urethane spray foam for instance Fill and Seal. Is there an outstanding which makes spray foam acceptable and rigid foam unacceptable?
That you are proposing an unusual way of insulating your roof. If I recognize you effectively, you want to install EPS amongst the tops within your roof trusses and your roof sheathing.
Thanks yet again. The roofer agrees that 2x4 framing to lift the peak above the vented attic can be a workable Option to match up the roof strains.
This is the common remedy for people who need to comply with most setting up codes (the answer arises from an write-up by Mike Guertin):
Effectively the roof is happening with the primary layer of insulation (on-best the purlins, underneath the roof sheeting). There seems to become adequate House still left from the 4" purlin cavity for the second layer of R11 being installed with no modification.
Manufacturers of soffit vents and ridge vents typically specify The web free of charge vent area of their items on item special info packaging or in specs offered on the web.