I thanks for this impeccably timed weblog, as I am at the moment framing my semi-essential cathedral ceiling hip roof (with shorter ridge). I want to describe my detail and check out to grasp the place I am on the appropriate observe and much more importantly, wherever I should have failures. Hope I am able to amuse some of you...I come to feel such as additional I try out to deal with a concern, the more of a priority it will become, And that i certainly don't want to choose excellent time, care, and detail to aid the demise of my roof.
I have already been working with rigid breadboard design and style expanded polystyrene in the rim joists and considered the exact same may be set under the sheathing concerning the rafter bays, and with any gaps sealed which has a urethane spray foam such as Fill and Seal. Is there a high quality that makes spray foam suitable and rigid foam unacceptable?
for an unvented design without insulation higher than the sheathing, what about making use of wood fibreboard among the rafters immediately underneath As well as in connection with the sheathing? All gaps between the boards and also the rafters full of expanding foam / sealant. You could possibly then cover the rafters with rigid foam to convey your insulation as much as required R amount and lessen the chance on the rafters and sheathing, and after that install your airtight drywall beneath this.
When your climate is just not much too intense It can be likely okay to obtain just the R-10 foam more than the structural metal, Though you can find some possibility the metal could sweat in cold temperature. I'm assuming You furthermore mght meant to insulate the 2x12 joist bays to Get the overall R-price to a reasonable level.
A lot of my neighbors right here have cathedral ceilings, no attics and absolutely no insulation (generally they have aluzinc roofs on plywood with pine rafters).
This post was extremely useful and looked as if it would provide a large amount of recommendation on cathedral ceilings. But what what my perfect storm? Your home is 30 many years outdated (eighty's) and im sure the ceiling isn't air restricted. I want to do one thing this summer season/tumble to test to fix these leaks but I'm worried that no matter what I do wont operate and may be described as a squander of cash, Particularly since I havent heard about a strong Answer.
Your intend to use two-inch-thick EPS as your ventilation baffle will do the job. The EPS is to some degree vapor-permeable, so it will allow a small amount of outward drying. (In almost any situation, in the event you Establish a reasonably airtight ceiling, there won't be any dampness On this assembly that needs to escape.)
Q. "I have been making use of rigid breadboard fashion expanded polystyrene within the rim joists and imagined the exact same could possibly be place beneath the sheathing among the rafter bays."
BTW, for your foam type, I'm leaning toward XPS find out this here for the reason that 1) I contain the effect that ISO is somewhat fragile, which include if it receives in any way soaked, and a pair of) the possibility of long term outgassing with ISO. Hopefully any such outgassing would go upwards and outwards instead of downwards into the house interior, but the prospect that it might outgas into the inside really problems me.
Q. "Ought to I Chunk the bullet and hazard of spray foam insulation, or deliver the builders again up on the roof in December to chop ridge and soffit vents?"
The roof seems to have a layer of asphalt shingles about the sheathing using a tin roof about that. The soffits are shut off. Your house is way off the crushed path and It truly is challenging to get any contractors available to work, let alone offer bids so I'm basically alone.
1. Your recommendation is only a slight variation on the element which is presently reviewed in my web site, specifically cellulose mounted having a vent channel in between the top of the cellulose as well as the roof sheathing.
Okay, so I am a little fearful examining this thread. I've a terrific place that is definitely paneled on top of the rafters, which can be 4x8, And that i installed sloped cans and was likely to insulate and end ceilings. My Principal objective of performing this would be that the roof is specifically to the beams and it gets quite hot in the summer, Wintertime not much of challenge as I are in San Diego and temps rarely dip down below freezing.
If you select not to extend the rigid foam more than the elements of your roof that have a conventional vented attic, your builder (or an architect) can come up with a trim depth that you just might be able to live with.