I've a mansard roof with steep sides with gables, and a nearly flat top rated that has a rubber roof. There isn't any vents, it has never been insulated before I started out focusing on it and possess two inquiries:
As The top of our nearby HBA, I've strenuously identified that foam in excess of a vented flat roof assembly isn't going to give the insulation values promised. Some builders have instructed they may just seal and stucco about the stucco vents and get rid of the air flow.
Builders resolve this problem by furring down or scabbing on added framing below the rafters to deepen the rafter bays. One more system is to include a layer of cross-hatched 2x4s, 16 inches on Middle, mounted beneath the rafters."
Thanks - this is new construction, I'm the designer / builder, and the greater I check out it, I am liking all rigid - less fussy. The highest layer of rigid over fluffy makes my eave way too thick anyhow. The air barrier with the T&G ceiling is actually the sandwich of felt and taped 3/8" CDX.
I imagine that most contractors would stress about the buildability of your technique. The Image displays a reduced-slope roof more than a flat ceiling; This permits staff to face over the ceiling joists.
Insulated cathedral ceilings are a comparatively the latest phenomenon. The trend for insulated cathedral ceilings (and great rooms) definitely took off while in the nineteen seventies and 1980s, when illustrations began popping up like mushrooms following a warm rain.
. Unvented roof assemblies are Safe click for more info and sound. The main reason that a number of people install ventilation channels higher than the rigid foam is because they are now living in parts with a lot of snowfall, and they like a "cold roof" to reduce ice damming challenges. Many thanks for your comment. I'll edit my report to test to clarify any ambiguity on this concern. .
A. There's a code necessity for your vapor retarder in certain forms of assemblies, but there is no prerequisite for your vapor barrier. Your layer of rigid foam is by now a vapor retarder. No more vapor retarding layer ought to be installed.
I doubt that the condensation is occurring against the chilly ridge beam. Fairly, I do think it is probably going that condensation is happening about the underside of one's ridge shingles or perhaps the underside of the asphalt felt underlayment.
four. Once you've R-twenty or R-25 of rigid foam in addition to your sheathing, you could properly insulate below your sheathing with almost any type of insulation you would like to use to bring your insulation around minimum amount code specifications.
It feels like a superb plan. Depending on what sort of rigid foam you select, you can end up having insulation during the array of R-16 to R-24. Even though that is below code prerequisites, It can be much, a lot better than what you may have now.
I'm not sure what to do concerning the electrical for the existing admirer, and for that not-still-installed but Substantially wished-for track lighting. In the old roof, the admirer's electrical source ran on top of the T&G ceiling, and was lined by what looked like electrical tape, then by a one/2" layer of seem insulation board, after which you can from the felt and shingles.
Do not make any hasty decisions that you will regret. If required, explain to your roofer to prevent all Focus on this undertaking right up until this problem is resolved (assuming, needless to say, that the roof sheathing is secured by asphalt felt or an identical underlayment.)
It's a code violation to put in an air-permeable insulation like fiberglass batts in between unvented rafters. It is Web Site also a bad concept, simply because dampness can accumulate on the roof sheathing if you are trying this technique, and you may end up with sheathing rot.