My guidance could be to seal the prevailing vents. If insulation contractors in your area are installing 3 to 4 inches of closed-mobile spray foam over the roof sheathing, there's no need to stress about condensation or humidity accumulation inside your sheathing.
It is sensible to verify the best layer of sheathing can dry to the outside when utilizing rigid insulation on an unvented cathedral ceiling. But what about the advised water-proof underlayment for valleys, eaves, and lower-slope sections of roof?
Thanks for the recommended addition into the listing of resources for making web page-designed vent baffles. I have edited the textual content of my site to include your recommendation.
What acquired me began on the "air restricted walls and roof sheathing" was your article of precisely the same title; precisely South Mountain Company's great posting within the Martha's Vineyard housing development. I noticed Marc's presentation on those homes at BBD in addition.
two. When you set up fiberglass batts, air limitations are much more essential than vapor control. You'll need a superior air barrier on both sides of your respective fiberglass batts.
If you're creating a cathedral ceiling, the most significant air-barrier blunder is to setup tongue-and-groove boards as your finish ceiling devoid of initial putting in taped gypsum drywall. A board ceiling is notoriously leaky, and this sort of ceiling is often related to roof sheathing rot.
This text was incredibly informative and looked as if it would provide a ton of recommendation on cathedral ceilings. But what what my perfect storm? The house is thirty several years aged (eighty's) and im guaranteed the ceiling isn't air restricted. I want to do a little something this summer time/slide to test to repair these leaks but I'm nervous that what ever I do wont operate and can certainly be a waste of cash, In particular considering that I havent heard about a stable Answer.
Perhaps the solution to go is usually to accept four" of froth more than the cathedral ceiling, as opposed to eight" of foam, rather than keep on the foam over the vented attic. There'll be considered a Bizarre jog during the roof line wherever the foam begins, but it can largely only be visible with the back again of the house, not from the road.
As a result of their unscientific origins, code prerequisites for venting roofs are frequently misunderstood. It’s truly worth setting up some essential facts:
Although the GBA Web page by now consists of lots of posts on The subject, we continue on to receive Repeated questions about the best way to insulate a cathedral ceiling.
If I am now not intending to get enough below-deck air flow due to The lack to obtain suitable soffit vent air intake, could it sound right to only skip the endeavor at roof ventilation and maybe rather place one" XPS in place of the vent channel about the underside of the present roof deck? (It is labor intensive, however , you can reach a pretty tight in shape concerning the rafters.
I'd wish to use the outside wall and roof sheathing as my primary air barrier; cdx plywood with all seams taped, which type of forces me to maintain the roof venting on top of the roof sheathing, as you describe in paragraph 7 of this short article. I would want to use Solitex Mento as a permeable roofing underlayment, as well as a WRB on vertical partitions, and 2 layers of cross hatched 1x4 strapping in excess of roof ply and Mento; 1 managing down the roof slope, nailed to your rafters, and the second run horizontally in excess of them to aid corrugated steel roofing.
Do not make any hasty selections that you'll regret. If required, tell your roofer to halt all Focus on this venture until this situation is fixed (assuming, obviously, that the roof sheathing is secured by asphalt felt or an analogous underlayment.)
If you'd like to endeavor a midway Remedy that might or might not function, it is possible to cut out a number of the drywall close to the ridge, and set up spray foam insulation about the underside with the roof sheathing, just in find this the area near the ridge beam.