A. You should only use an installation method that your insulation contractor is accustomed to. In this article within the Northeast, many contractors would almost certainly fill your rafter bays utilizing the dense-pack system immediately after your new roof sheathing was installed.
I'm coping with slightly distinctive condition that I'd enjoy some input on. I am developing a Vineyard tasting home inside a masonry developing (8" monolithic concrete walls) in 4C/5B climate zone in So. OR. I have received an exposed 2x10 T&G ceiling in excess of GLB purlins @ five'oc, so I'm setting up it from the bottom up and the last layer to go on is the sheathing underneath the steel roofing. I had planned to set up an air barrier around the T&G deck (taped felt) then frame 2x8 @ 24"oc with substantial density batts to fill the cavities, over which happens to be the sheathing under the metal roofing.
This article will discuss insulated sloped roofs. The procedures explained listed here can be utilized to construct an insulated cathedral ceiling over an excellent room, a bit of sloped roof over a kneewall, or any equivalent area of insulated sloped roof.
Q. "If I set up a polyethlene sheet between The underside with the batting as well as sheetrock [it would be connected on the purlins], wouldn't this be an interior vapor barrier?"
If you like, you are able to Find your ventilation channels on top of the roof sheathing rather then underneath the roof sheathing. If you decide to do that, Be certain that any roofing underlayment that you put in earlier mentioned the roof sheathing is vapor-permeable — published here one example is, #15 asphalt felt, VaproShield SlopeShield, or Solitex Mento — and that your local making Division accepts this method of roof venting.
As for my Electrical power auditor recommending blowing cellulose into the mansard sides, You furthermore mght suggest versus that? I had been beneath the effect blown cellulose prevents moisture migration.
Feels like you have the framing and roofing set up. Your choices are explained from the report higher than--you could increase venting by setting up baffles under the sheathing to carry again the insulation, or you are able to install not less than R-20 of air impermeable insulation.
Most rafters aren’t deep adequate to support the insulation required to satisfy minimum amount R-values necessary by code, particularly if the rafter bays consist of a ventilation channel.
My feeling is always that if we are concerned about air leakage compromising the insulation's success, vent channels are problematic.
With my property the middle area (20ft) is vaulted, a 3x12 slope and has eight recessed lights during. I have had leaks in quite a few locations in this area of the house, the leaks come about with the thaw and refreezing. It obtained The purpose last calendar year where by I needed to shovel the complete roof just after Every single snow tumble.
While roof ventilation can help dry out moist roof sheathing, it’s necessary to Restrict the flow of drinking water vapor escaping with the property so that the roof sheathing under no circumstances receives moist to begin with.
I should wonder In case the failure from the Picture would have occured In case the hip and ridge was vented and everything else the exact same?
4. After getting R-20 or R-twenty five of rigid foam on top of your sheathing, it is possible to properly insulate beneath your sheathing with Practically virtually any insulation you want to use to deliver your insulation as many as minimum code demands.
My feeling would be that the steep aspect of a mansard roof is often a roof. This is especially true if the exterior of your sloped assembly is concluded with roofing.