Our cooler mornings may possibly make the inside of my metallic roof sheeting to sweat a little given that It will likely be in connection with the hotter unvented fiberglass-insulated purlin "cavity" underneath. As soon as our very hot Caribbean sunshine starts to kick in I need this humidity to dry and/or diffuse out of the cavity, throughout the gypsum sheeting, to the cathedral dwelling Place beneath, to then be blown outside of my 4x3 gable window. A vapor barrier would totally retard this process.
So a hybrid method has to be investigated. Dense packed cathedrals with warmside ridged foam to add R, taped, no recessed lights or other air paths after which belt and suspenders... Add venting While there isn't a standard one" vent path.
On the topic of fluffy insulation, are there any sources you'll be able to refer me to which handle the distinctions between low, medium and significant density fiberglass batt insulation with the standpoint of lack of R-Benefit resulting from wind-wash (no matter whether because of air infiltration or convection because of important temperature variances front to back)?
It appears if a single were being to make use of dense pack cellulose in the vented cathedral ceiling the vent channel materials ought to be rigid enough to resist the force.
I have insulated the perimeters with R-19 fiberglass and now I am pondering: was that a error? It's craft paper and I was scheduling on the plastic sheet in addition, need to I skip that?
I should wonder When the failure during the Image might have occured In the event the hip and ridge was vented and anything else the identical?
First, is it easy to determine no matter if a roof is ventilated? If no soffit vents or aspect vents are noticeable about the roof from the bottom, does that necessarily mean the roof just isn't ventilated?
If this were being my dwelling, and if the fiberglass batts are noticeable, I'd personally pull all of the insulation out of some rafter bays to discover what is actually up there.
Set up a layer of closed-mobile spray foam towards the underside from sites the roof sheathing, and fill the remainder of the rafter cavity with the air-permeable insulation. All over again, this kind of assembly is intended to dry to the inside, Therefore the assembly need to never ever involve an interior polyethylene vapor barrier.
My dwelling built in 63 below in Ohio incorporates a cathedral ceiling with no air flow. In truth there a lot of cross-supports operating perpendicular to the main joists and other framing factors that will make this unfeasible. So I want to make it a powerful unvented roof. 50 percent in the roof has 2x8 joists and the other fifty percent has 2x12s. At the moment There exists a membrane covering (rubber) that's labored nicely for over twenty years but is exhibiting indications of deterioration and could need to have changing quickly. Possessing done reworking on The within and strolling on the roof I realize that plenty of the sheeting ought to get replaced along with the very little insulation that may be there now. We have experienced condensation troubles before so I now you'll find air infiltration and bridging difficulties.
If you need to do as you suggest, you would gain an addition take pleasure in the R-20 insulation above the roof sheathing. Having said that, the tactic you describe wouldn't satisfy code necessities For brand spanking new construction, because ideally any insulation utilized to health supplement the rigid foam higher than the roof sheathing ought to be in immediate contact with the underside with the roof sheathing.
A. In the event your goal is to set up a great air barrier, then drywall is certainly sufficient, so long as you seal all penetrations to stay away from air leakage. For more on setting up drywall within an airtight method, see Airtight Drywall.
If you put in 2x4s (or 2x3s on edge, mounted with lengthy screws) perpendicular into the rafters, you are going to deal with a look these up lot of the thermal bridging worry with no need to increase a layer of rigid foam.
If We will place some insulation previously mentioned the ceiling, then I desire to set Every one of the insulation over the ceiling, and steer clear of the Charge and inconvenience of a different lowered ceiling. Which means a Construct-up of eight", applying XPS. If we Construct up the roof line above the cathedral ceiling of the family members home by 8", we presumably need to create up the rest of the adjoining gable roof at the same time.