(d) There may be ample air leakage in the "soffit" and ridge to deliver air flow that functions the best way a ventilation hole ordinarily would.
My belief would be that the steep side of the mansard roof is a roof. This is especially true if the outside in the sloped assembly is finished with roofing.
Thanks for that responses. We won't ever A/C the making (It will probably be photo voltaic powered). The wind is rather constant, but it is a humid atmosphere, so moisture Command is unquestionably on my thoughts.
two. When you put in fiberglass batts, air obstacles are far more important than vapor Handle. You'll need a excellent air barrier on each side of your fiberglass batts.
Can I get some far more commentary within the "full roof" of Ice & H2o Defend? I believe this experienced very little to complete Using the failure. The main reason why I check with is I've the same "complete roof" structure developing, Nevertheless, the rafter bays are all straight runs with soffit vents, constant vent baffles (one/2" plywood) and continual ridge vent. Dense pack cellulose, 2" XPS under 2x10's, air tight drywall (XPS might be sealed up much too).
Joe Lstiburek: "A vented attic, where by insulation is placed on an air-sealed attic ground, is One of the more underappreciated developing assemblies that We've got while in the heritage of developing science."
A. As I wrote during the report, "Most rafters aren’t deep more than enough to accommodate the insulation required to satisfy minimum amount R-values expected by code, especially if the rafter bays incorporate a ventilation channel. ...
Thanks on your reaction Martin. Would you continue to be content to make use of that unvented system for your renovation predicament wherever There is certainly non-breathable membrane (eg bitumous 'felt') above sound board sheathing?
If I'm presently not intending to get sufficient less than-deck ventilation as a result of The lack to get enough soffit vent air ingestion, may well it sound right to only skip the endeavor at roof ventilation and perhaps rather put one" XPS instead of the vent channel about the underside of the present roof deck? (It is labor intensive, but you can reach a fairly restricted healthy involving the rafters.
In case you are deciding on to develop a vented roof assembly, don’t published here overlook to incorporate soffit vents and ridge vents.
If you wish to choose a fabric which is a bit much more vapor-permeable for your personal air flow baffle, you can -- for instance, some people use thin plywood or fiberboard In this particular location -- but you really do not have to. The EPS will get the job done
With regards to dense pack cellulose: not sure why dense pack would recommended you read be negated - I think it completely suited.
Make certain the roof assembly is as near airtight as you can also make it. If you are using fluffy insulation, you will need two air limitations: 1 beneath the insulation, and one particular previously mentioned the insulation.
I have already insulated the steep sides of my unvented mansard roof with 6" fiberglass (and I had it inspected), would you advise I rip that out and use spray or board foam? I have gotten conflicting details on whether or not to deal with it as being a wall or maybe a roof.