If you'd like to produce a conditioned attic, this text lets you know what you have to know. To find out more on The subject, see Creating a Conditioned Attic.
My feeling would be that the steep facet of the mansard roof is really a roof. That is especially true if the outside from the sloped assembly is completed with roofing.
On the subject of fluffy insulation, are there any sources you may refer me to which address the variations amongst minimal, medium and large density fiberglass batt insulation from the standpoint of loss of R-Worth as a consequence of wind-clean (whether as a consequence of air infiltration or convection as a result of major temperature variances front to again)?
Again on the vent idea. I really Consider venting a roof that is certainly airsealed in the interior very well and built devoid of vent chutes is quite possibly The easiest method to build cathedral ceilings.
Positive It truly is a great deal of issues. It looks like a lot less trouble which the detail posted as case in point from the website earlier mentioned and takes advantage of no foam... That is a "biggie" for me.
Evidently, at times you need to strategy ahead to be sure that your rafters are sized sufficiently to allow for insulation and venting. For more information on satisfactory solutions to insulate lower-slope roofs, see this text: Insulating Minimal-Slope Household Roofs.
If you need a vapor-permeable material that remains an air barrier, opt for fiberboard sheathing. But use caulk round the perimeter, and tape for the seams, to be sure that the fabric is set up in an airtight manner.
On an unrelated matter: The Chilly Weather Housing Analysis Center has manufactured a online video (beneath) exhibiting one particular way of creating an insulated cathedral ceiling. The tactic revealed inside the movie is especially suitable for builders in climates topic to ice dams.
BTW, for that foam type, I am leaning towards XPS because 1) I possess the perception that ISO is to some degree useful site fragile, like if it will get in the slightest degree wet, and a couple of) the potential for long-term outgassing with ISO. With any luck , any such outgassing would go upwards and outwards rather than downwards into your home interior, but the chance that it will outgas into the inside genuinely anxieties me.
My understanding as I read through this blog site is usually that I do not have to worry about building an air channel higher than the sheathed part as a result of rigid foam.
It is really great to include foam board previously mentioned the roof deck Despite the closed cell foam-board (what variety?) on the interior. Roof decks are not able to dry to the exterior through 0.one for each shingles in any case, significantly given that in zone five it will expend a big length of time lined in snow/dew/rain Along with the dampness generate heading inward, not outward.
I do think you necessarily mean this: Your cathedral ceiling is presently uninsulated. If you are indoors seeking up, you are able to see your rafters. Previously mentioned the rafters it is possible to see a layer of boards. Is the fact correct?
I live in northern Vermont, and I don't have plenty of experience see post with air conditioning to answer your concern about condensation on interior ducts.
JB- I really must submit sketches as Ken did. It could probably save some trouble. For me this was additional reading harking back again into the compact roof string.