We will give it a try. Existing is a fourteen yr outdated roof with 2" of closed cell roofing foam using an acrylic elastomeric coating.
I might add to Martin's list of resources for rafter vent channnels, fiberboard sheathing. I use I joists for vented cathedral ceilings and staple one/2" fiberboard to the bottom of the top twine of your I joists. It might be ripped on a table saw and installs speedily, fiberboard does Have a very superior perm rating and should allow compact quantities of humidity to pass through to the vent space.
Most rafters aren’t deep sufficient to support the insulation necessary to meet least R-values demanded by code, particularly if the rafter bays involve a ventilation channel.
If your local weather just isn't far too intense It can be most likely ok to own just the R-ten foam above the structural steel, Whilst there's some hazard that the steel could sweat in chilly weather conditions. I am assuming You furthermore may intended to insulate the 2x12 joist bays to Get the overall R-benefit to an affordable stage.
It appears if a person have been to use dense pack cellulose inside a vented cathedral ceiling the vent channel content ought to be rigid ample to resist the pressure.
Energy codes create minimum amount R-benefit demands for roofs and ceilings. There are many feasible code compliance paths; most builders choose the prescriptive path, which sets forth minimal R-values for roofs and ceilings in a prescriptive table.
We really Do not know if these roofs have right vent channels, or what type of vent baffles (if any) were utilized to take care of the air flow gap amongst the very best with the fiberglass insulation as well as the underside in the roof sheathing.
U.S. building codes never call for the usage of inside vapor limitations, even in chilly climates. The things resource they do need can be an interior vapor retarder. This need is often happy with kraft struggling with on fiberglass batts or vapor-retarder paint.
moisture to move out within your ceiling. The point is to try to manage any dampness which makes its way there in spite of
If you want to choose a material that may be a little bit a lot more vapor-permeable to your air flow baffle, you may -- such as, a lot of people use slender plywood or fiberboard in this area -- but you truly do not have to. The EPS will work
two. I do think your proposed element can be tough to Develop. How effortless can it be to balance over the rafters as you put in the membrane, presumably with staples, after which you can install the 2x2 spacers, presumably with nails or screws, all with no Placing a foot involving the rafters? I wouldn’t want to do it.
If not, he won't get to refuse to put foam previously mentioned the sheathing, which would be improved and less expensive than fitting it between the beams.
I ordered a catastrophe of a house that was partially remodeled, It is really in Zone 16 (a California designation comparable to IRC zones). It has a six/12 vaulted ceiling in excess of the dwelling/kitchen area. The roof is held up by two extended beams that operate four ft out parallel to your ridge , Hence there isn't any straight air path a the way in which as much as the peak ridge beam.
Because the point of your string is making roofs that don't fail, there are likely to be assemblies that really perform properly but are some a departure. If we experienced the very best tactics that we could at any time think about, currently in hand and on occupation web sites, we wouldn't be in this article (at GBA) and Martin would've much considerably less to accomplish.