My tips would be to seal the present vents. If insulation contractors in your area are installing 3 to four inches of shut-cell spray foam previously mentioned the roof sheathing, there's no need to worry about condensation or humidity accumulation as part of your sheathing.
In order to produce an unvented insulated roof assembly, you may have two options: (a) You are able to include rigid foam to the outside side of your roof sheathing, followed by a next layer of roof sheathing and new roofing, or (b) It is possible to insulate the underside of your respective roof sheathing with spray polyurethane foam.
I looked at the unvented schematics and I am not certain that fits the bill for up here (Canada - west coast).
In keeping with area R806.3 of the 2006 Worldwide Household Code (IRC), “No less than a 1-inch Place shall be presented amongst the insulation as well as the roof sheathing and at The situation in the vent.†Such a vent Place might be designed by installing one inch by one inch “sticks†while in the higher corners of each rafter bay, followed by stiff cardboard, skinny plywood, OSB, fiberboard sheathing, or panels of rigid foam insulation.
2. When you put in fiberglass batts, air barriers are a great deal more critical than vapor Command. You need a excellent air barrier on both sides of one's fiberglass batts.
Make sure to put in insulation that gives at least the bare minimum code necessity for ceiling R-value. Insulation that exceeds the least code requirement is even better.
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I am unsure in the event you are interested within a constructing science solution or simply a code reply. From a code point of view, this is the roof that needs to be insulated to R-forty nine.
It can be a great deal more essential to have an interior this content air barrier than an inside vapor retarder. Ensure that you've produced a superb air barrier by sealing all penetrations and cracks.
Having said that, two other parts of aspect-roof have presently been dry walled around with fiberglass plus a plastic sheet -- the toilet closet and also the hallway. I am concerned to talk to but ought to I open All those up once again?
With the roof assembly over the cathedral ceiling, does the stack-up below capture all The weather I would want? 2x8 pine T&G (by now her explanation in position, continues to be since the finish ceiling)
Ventilation channels are produced by installing a cloth which can sustain a separation (an air hole) among the insulation as well as roof sheathing.
It seems like you have got an present roof with tile roofing. I am guessing that you are writing from Europe. It sounds like the insulation includes "restricted-fitting wood fibre board" in between your rafters -- thickness and R-worth aren't specified.
Re: the air barrier to get positioned previously mentioned the pine T&G ceiling and below the foam, would you advise that we use a thing and that is both equally an air barrier in addition to a vapor barrier? Or could it be critical to make certain that the products we pick out will not be a vapor barrier, to make sure that any humidity that gets in to the roof assembly can dry to The within?