If you'd like to use just one form of insulation in unvented rafter bays, you will be restricted to spray polyurethane foam. A different probability, not surprisingly, is to make your roof with structural insulated panels (SIPs).
I'm undecided how to proceed concerning the electrical for the prevailing supporter, and with the not-still-installed but much wished-for track lights. While in the old roof, the fan's electrical supply ran in addition to the T&G ceiling, and was protected by what looked like electrical tape, then by a one/2" layer of sound insulation board, and afterwards via the felt and shingles.
I had been skeptical of Invoice Hulstrunk's assert that AccuVent baffles could withstand currently being dense-packed within an enclosed cavity.
Did you know the initial supply for this Photograph and when it is achievable to see other photos of the intriguing failure.
"R-19 batts are extremely air permeable, and on prolonged unobstructed rafter bays you might have fairly a stack impact. It does not take a enormous amount of air leakage to provide some drying there. Also, In the event the batts are unfaced or kraft-faced, the drying toward the interior will be considerable.
Incredibly handy (5*) thread. So, if you must use fiberglass insulation batts, and also you dont have entry to spray foam or shut cell boards, what do you do? I assume the key is to really make it unvented and insert in other air-impermeable layers. I'm about to insulate a completely new all-steel cathedral pitched gable roof while in the Caribean. The approach would be to fill the cavity between the four" Z-purlins with R-11 batting (vapor facet going through the living Room). For added heat conduction resistance we decide to roll Yet another thinner (filleted?) layer of this batting excessive of the purlins (ie among the purlins plus the sheeting).
I think you necessarily mean this: Your cathedral ceiling is presently uninsulated. When you're indoors looking up, you can see your rafters. Earlier mentioned the rafters you'll be able to see a layer of boards. Is that proper?
I've crafted log homes while in the Yukon Territory in northern Canada for 30 many years. Most log properties have cathedral ceilings. Most of the roofs We've developed are as follows (from The underside up): log purloins, nominal 2" (2x6) t&g decking, 6mil poly, one 1/two" extruded polystyrene foam, 2x10 rafters on 24" facilities, 7" fiberglass, 2x4 strapping, seven/sixteen OSB, underlayment (15 lb paper, 30lb felt, or now we might even use ice and h2o defend). There could well be about an inch of air House underneath the strapping for equally vertical and horizontal air movement. All roofs are vented with strip vents within the eaves and vents during the soffit (2x6 t&g) at the height at each ends. I might disagree that venting is not needed in case you halt the airflow on the warm side, for two good reasons. Initially it really is very difficult to prevent all airflow, Particularly with conventional standard practices (ie chimney and plumbing vent penetrations with the roof) Now we have several techniques designed over learn the facts here now time to seal the vb within the eaves and gables, but there remain nail penetrations in the vb. All round I do think we had quite tight seals but one particular could hardly ever say airtight.
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Eventually (I assure This is often my very last subject matter). Regarding my fiberglass batts: Will the going through that comes with it retard the drying out system that I explained above (will it make any difference what facet I place it on inside the purlin cavity?
If you decide on to setup open up-cell spray foam rather than closed-mobile spray foam, your roof assembly will be able to dry to some degree to the inside. Just make sure that the spray foam layer is thick enough to maintain your rafter bays previously mentioned the dew position over the Winter season.
Doug... For many explanation I did't see your write-up #17. Looks like two of us at the least Feel there is likely to be a super easy low-cost Answer.
If you're creating a cathedral ceiling, the most significant air-barrier blunder is to install tongue-and-groove boards as your complete ceiling without initial putting in taped gypsum drywall. A board ceiling is notoriously leaky, useful reference and this sort of ceiling is commonly affiliated with roof sheathing rot.
Numerous spray foam roofing contractors within our current market are touting their potential boost performance on old incredibly hot tar and investigate this site graveled flat roofs by introducing three to four inches of shut cell spray foam. Most of these previous houses are flat roofs joisted with dimensional lumber, with parapets and have stucco vents Slash to the rim joists.