I'd insert to Martin's listing of materials for rafter vent channnels, fiberboard sheathing. I use I joists for vented cathedral ceilings and staple one/2" fiberboard to the bottom of the best wire in the I joists. It might be ripped over a table noticed and installs immediately, fiberboard does Use a large perm score and could allow for little quantities of humidity to go through into your vent Room.
However, I think you might be Incorrect about your asphalt felt; I doubt If your felt is impermeable to drinking water vapor. Most varieties of asphalt felt are relatively permeable -- typically 5 perms when dry and up to sixty perms when soaked.
It's Secure to state that an current home doesn't have excellent roof air flow if there are no soffit vents or ridge vents. It's also Secure to declare that, even when there are actually soffit vents and ridge vents, the roof isn't ventilated if it features valleys, hips, dormers, or skylights.
If you want to develop an unvented insulated roof assembly, you probably don't want to disturb the tile roofing. That means that essentially the most suitable insulation will be spray polyurethane foam. Certainly, the existing insulation should be eliminated ahead of you put in the spray foam.
Most of my neighbors here have cathedral ceilings, no attics and Completely no insulation (mainly they've aluzinc roofs on plywood with pine rafters).
I such as depth presented but I would not contact that a cathedral ceiling condition mainly because it contains ceiling joists spanning at the bottom of the roof rafters. I'd simply call this an insulated attic.
Here's what you wrote: "I'm sure that there is no caulk/sealant in between the facet from the beam as well as area in which the drywall butts towards it, so You will find a smaller air hole there. My memory is the fact fiberglass insulation was utilised. There is without a doubt no vent in the roof."
I wish to thoroughly insulate my cathedral ceilings and was contemplating to spray two inches of shut mobile foam to sheathing, then fill with dense packed cellulose. I am wondering if I can attach craft paper and pine paneling into the 2x8 rafters after which fill the bays with cellulose.
Thanks again. The roofer agrees that 2x4 framing to raise the height more than the vented attic will be a workable solution to match up the roof strains.
Did you know the first source for this Photograph and if it can be done to check out other photos of this intriguing failure.
You can skip the tape on the highest layer of plywood to exact some time and cash. That's most likely what I'd do if I have been you. Having said that, there isn't a hurt in taping the seams of the best layer of link plywood.
to install vent channels among the top with the rigid foam and the top layer of roof sheathing. I never ever claimed that it had been needed
I was skeptical of Invoice Hulstrunk's declare that visit the site AccuVent baffles could endure staying dense-packed within an enclosed cavity.
I now know that stucco cannot be applied to a roof, so I'll revert for the a metal roof, but nevertheless want to own an unvented attic. I've read by way of "Developing a conditioned attic", and am nevertheless unsure regarding The simplest way to progress.