In some cases, these air flow channels are set up above a layer or two of rigid foam. It’s also probable to get nailbase (a variety of SIP with OSB on a single side as an alternative to two) that includes integrated air flow channels between the OSB along with the rigid foam; just one manufacturer of such panels is Awesome-Vent from Hunter Panels.
Q. "Considering that I am setting up from above would something like stabilized cellulose perform since it has slightly water added? I'd personally imagine loose fill could blow everywhere in the community!"
U.S. constructing codes will not demand the use of inside vapor boundaries, even in chilly climates. What they do need is an inside vapor retarder. This need may be pleased with kraft struggling with on fiberglass batts or vapor-retarder paint.
[Editor's Notice: Bill Rose just sent me the following responses within an e-mail; he incorporated his permission to submit the opinions.]
I haven't got expertise creating while in the Carribbean or building steel properties, so I am not the very best particular person to comment. But here are a few reflections:
The reason To place the additional insulation in contact with the underside of the roof is usually that It really is difficult to confirm you have properly shut off all vents to the attic. However, if you truly do reach carrying out that, there should be no difficulty. With a blower doorway is possible, though tricky.
Here is what you wrote: "I'm sure that there is no caulk/sealant in between the aspect on the beam and the location wherever the drywall butts against it, so there is a tiny air hole there. My memory is always that fiberglass insulation was utilized. There is without a doubt no vent from the roof."
Install closed-cell spray foam versus the underside on the roof sheathing, and no other kind of insulation. Make certain that the thickness in the spray foam is suitable to meet bare minimum code needs. Bear in mind open-cell spray foam is dangerous in all local weather zones, and if open up-mobile spray foam is installed Within this site in a chilly local weather, the underside with the cured foam have to be protected with gypsum drywall that has been painted with vapor-retarder paint. Vapor-retarder paint is ineffective whether it is sprayed straight within the cured foam.
Ought to I take advantage of airtight baffles or not, I don't see a means to have dampness escaping inside a assembly with airtight baffles, fiberglass and xps on the inside, no matter what the dew position might be inside of this assembly And maybe develop condensation that can't evaporate with no ventilation.
My comprehending as I read this blog is always that I would not have to worry about producing an air channel over the sheathed part as a result of rigid foam.
Martin, thanks. I just talked on the roofer and he turned down the thought of only putting the foam about the spouse and children room cathedral ceiling. That Strange "jog" during the roofline, getting it quickly bump up 4" or eight" where by the loved ones area begins, in the midst of the back aspect on the roof, would defeat the concept of a continuous slope for rain to come back down when it hits the higher Section of that back roof. And so the 4" or 8" peak addition requires to his response carry on over the overall next story roof line.
Thinking about the deadly pic I sense there could be an easy nevertheless unorthodox Option. All the rot from warm soaked air meets cold wood is correct near to the place a vented hip might have averted all and Devoid of vent chutes.
My sense is if we've been concerned about air leakage compromising the insulation's efficiency, vent channels are problematic.
As your house flexes with modifications of temperature It is doable, even most likely that a lot of the foamed-in air sealing will leak. It might be truly worth executing two" of open cell foam on the interior facet of which might be a far more versatile and reputable long term air seal.