Your system will perform great, assuming that the layer of rigid foam in addition to your roof sheathing has an R-value of not less than R-20. When you are working with XPS, you may need at least 4 inches of froth. For anyone who is utilizing polyisocyanurate, you will need at least 3 inches of foam.
I'm unsure how to proceed with regards to the electrical for the existing enthusiast, and for that not-still-set up but Significantly sought after monitor lights. Within the aged roof, the enthusiast's electrical source ran along with the T&G ceiling, and was protected by what appeared like electrical tape, then by a one/2" layer of sound insulation board, then via the felt and shingles.
If I'm previously not planning to get adequate under-deck air flow due to The lack to acquire enough soffit vent air ingestion, may possibly it seem sensible to just skip the attempt at roof ventilation and maybe as an alternative place 1" XPS rather than the vent channel within the underside of the present roof deck? (It is labor intensive, however , you can reach a reasonably limited match in between the rafters.
November 18, 2011 Image 1 of 3 A leaky ceiling doomed the roof sheathing. The ceiling of this 10-calendar year-aged house was Slice for an electrical box, as well as oversized gap was under no circumstances caulked. Dampness-laden air entered the rafter bays via these cracks. If the humidity encountered cold roof sheathing, it condensed, resulting in humidity accumulation and decay. (The rubberized membrane while in the Image was employed as A short lived patch to get a gap during the roof, and did not contribute towards the failure mechanism.) Picture Credit score: Peter Yost A leaky ceiling doomed the roof sheathing. The ceiling of this 10-year-outdated household was Slice for an electrical box, as well as oversized gap was by no means caulked. Moisture-laden air entered the rafter bays by means of these cracks.
Using ventilated nailbase panels is a perfectly great way to create a cathedral ceiling. The identical regulations implement as when employing SIPs: ensure that the seams are sealed being as airtight as you can make them, and make sure that the total R-price of your roof assembly fulfills or exceeds minimum amount code R-value specifications.
My tips would be to seal the prevailing vents. If insulation contractors in your town are installing three to four inches of shut-mobile spray foam earlier mentioned the roof sheathing, there's no need to be worried about condensation or moisture accumulation in your sheathing.
It's really a code violation to set up an air-permeable insulation like fiberglass batts between unvented rafters. It is also a bad concept, for the reason that humidity can accumulate on your roof sheathing if you try this technique, and you'll end up having sheathing rot.
I suspect that Invoice Rose is right: all of these failures involve moisture that may be carried by shifting air. These are not diffusion failures. When the rafter bays definitely are appropriately dense-packed -- a giant if -- the prospect of air movement is quite very low.
Here's what you wrote: "I do know that there's no caulk/sealant in between the aspect on the beam plus the put wherever the drywall butts from it, so You will find there's modest air hole there. My memory is the fact that fiberglass insulation was used. There is without a doubt no vent inside the roof."
With my house the center part (20ft) is vaulted, a 3x12 slope and it has eight recessed lights throughout. I've had leaks in quite a few locations in this area of the house, the leaks come about Using the thaw and refreezing. It got The purpose previous year where I had to shovel the whole roof right after Every single best site snow tumble.
We really Will not know if these roofs have proper vent channels, or which kind of vent baffles (if any) were employed to take care of the ventilation hole involving the highest in the fiberglass insulation and also the underside with the roof sheathing.
Louis Blues. Greater than nearly anything, he savored the less difficult factors in everyday life: heading for rides to Horseshoe Lake, enjoying card game titles with family, grilling, his backyard garden, feeding the birds and squirrels in his property and observing a superb western. He Particularly cherished the Christmas time, expending time with friends and family. He was liked by quite a few whose life he impacted, and he is going to be missed deeply.Â
If you want to use rigid foam, the most effective location to set it's along with your roof sheathing, not less than your roof sheathing.
I am a homeowner in Seattle. Have got a freshly-framed, vented cathedral ceiling to insulate. Straight bays, 2x12, 24" o/c. The current prepare is to implement batts of some type while in the bays, consider treatment to air seal the interior surface area, keep away from penetrations, air seal the vent channel as well (bays absolutely sealed), double key The within area for vapor resistance. I have a few questions about baffling the vent channel: 1. A lot of the making experts I'm working with experience the jury is still out on baffles and therefore are recommending leaving the batts open up into the channel except near the vents, assuming the 1-2" air channel might be taken care of.