Perhaps the approach to go would be to accept four" of foam in excess of the cathedral ceiling, as opposed to eight" of foam, and never proceed the foam in excess of the vented attic. There will be described as a Bizarre jog inside the roof line exactly where the foam starts off, but it is going to generally only be seen with the again of your house, not from the road.
I concur along with you: I'd like to see more details on this problem. I'm not aware of any failures which have happened in correctly dense-packed unventilated rafter bays.
Many of my neighbors right here have cathedral ceilings, no attics and Unquestionably no insulation (in essence they may have aluzinc roofs on plywood with pine rafters).
Let's say that a specific building apply leads to a 20% failure rate. That apply would be fully unacceptable to builders, who don't need callbacks or headaches. But that practice would however end in eighty% of consumers currently being satisfied.
You need to check with an electrician about the best way to provide your ceiling electrical containers. There are lots of possible remedies -- some seen from the inside, and some hidden by The brand new foam.
If you need to build an unvented insulated roof assembly, you probably don't want to disturb the tile roofing. Meaning that quite possibly the most proper insulation might be spray polyurethane foam. Needless to say, the prevailing insulation really should be eradicated right before you install the spray foam.
Here's the typical remedy for individuals who really need to comply with most making codes (The solution originates from an article by Mike Guertin):
Indeed, it is actually Protected (Even though before you inquire an issue about a specific roof assembly, It might be fantastic to grasp your climate zone).
Feels like you have the framing and roofing set up. Your options are described in the post higher than--you are able to incorporate venting by setting up baffles underneath the sheathing to carry back the insulation, or you can set up not less than R-20 of air impermeable insulation.
Have home more than garage Heart with closets on each side between the closet kneewalls and also the eaves. Insulation above the space part is 6 inches of froth slabs sealed by "Excellent Things" spray-in foam. Earlier mentioned this ceiling foam and underneath the roof plywood, you'll find 1 inch x twenty. inch unobstructed foam encased ducts amongst the rafters for venting to your roof peak vent. The aspect sections outside the knee partitions are insulated with rolled fiberglass fiber with durovent ducts in between the insulation and also the roof plywood. You can find significant soffit vents at the base with the durovent ducts.
The GBA Internet site doesn't deliver customized facts. That is what an architect or an engineer is for; I advise that you employ a person.
One more difficulty that comes up in that scenario is whether or not that could boost condensation over the underside on the 1" XPS when it really is cold sufficient outdoors as the underside from the XPS could be below the dew place? Q-3: What to do whenever we re-roof.
I am a tad stumped on this just one - I might want to vent this roof assembly, but I can not say whether there'll become a normal convective move as there could be with rafters sloping Together with the roof pitch. My rafters are running level Nevertheless they sit on parallel curved top plates. I can use twelve" Learn More rafters and make ten" of batt get the job done, leaving a lot of air flow Place. I am able to drill the tops with the engineered joist flanges to permit air flow 'up-slope' (perpendicular towards the rafters) along with within the rafter bays, and I can provide continual perimeter air flow (Cor-A-Vent strip) at my roof fascias (eave, ridge and gables).
Keep in mind, an insulated sloped ceiling isn’t generally a good idea. Often a good outdated-fashioned unconditioned attic is The easiest way to cap the house.