Our cooler mornings may well make the inside of my metal roof sheeting to sweat slightly due to the fact it will be in connection with the hotter unvented fiberglass-insulated purlin "cavity" beneath. As soon as our scorching Caribbean sunshine starts to kick in I want this dampness to dry and/or diffuse out of this cavity, in the gypsum sheeting, to the cathedral residing Room down below, to then be blown away from my 4x3 gable window. A vapor barrier would totally retard this process.
In order to develop an unvented insulated roof assembly, you've two possibilities: (a) You can insert rigid foam to the outside aspect of one's roof sheathing, followed by a second layer of roof sheathing and new roofing, or (b) You can insulate the underside of one's roof sheathing with spray polyurethane foam.
Many thanks to the comments. We won't ever A/C the developing (It'll be solar driven). The wind is very constant, but it is a humid setting, so humidity Handle is undoubtedly on my brain.
You should utilize Ice & Drinking water Shield as an air barrier if you want. But when you end up picking to implement that product or service, you'll have to remove the asphalt felt so the Ice & H2o Protect can be adhered on the roof boards.
A. To take advantage of the insulating price of the rigid foam in excess of the attic, you absolutely choose to seal up any attic vents, and also you unquestionably don't need to make a ridge vent.
You need to seek the advice of an electrician about The simplest way to provide your ceiling electrical containers. There are various possible remedies -- some noticeable from the interior, and a few concealed by the new foam.
Doug I agree, too many wrongs "overthinking" and overdoing. I when had to resupply a doctor constructing an aircraft with dozens of the plane bolts simply because they were being tightened to The purpose of breaking the bolts. A lot less is a lot more sometimes... Along with the KISS rule.
Many thanks once more for the responses. Now I just want to find an installer During this region who understands what they're carrying out (so far it's been iffy)!
Set up a layer of shut-mobile spray foam towards the underside in the roof sheathing, and fill the rest of the rafter cavity having an air-permeable insulation. All over again, this sort of assembly is built to dry to the inside, so the assembly must in no way include things like an inside polyethylene vapor barrier.
And so the question is: seal the stucco vents and insert the spray foam roof and Don't be concerned about condensation? There's hardly any lower-hanging fruit in our kind of building, Primarily on present residences, And that's why consumers are remaining sucked into your spray foam roof scam.
I've a 50 calendar year-previous seasonal cottage in a very northern climate. The simple 6/twelve gable roof is made wikipedia reference up of precise 2x6 rafters (24" oc), sheathed with one/2" plywood and lined with asphalt shingles. There is no insulation while in the ceiling and I think minimal to no successful insulation in the 2x4 walls. In the summertime the heat obtain inside makes residing Nearly unbearable. I believe that the most important bang for your buck would be to deal with the ceiling insulation situation to start with, but wish to preserve the inside look.
Thanks, Martin and Stephen. Thankfully we're in a very scenario wherever we can easily pause and reconsider, as The brand new felt has long been put, but they have not began putting in shingles but. I'll explore the specific situation With all the contractor yet again. I may be able to get him to reconsider.
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This is a code violation to setup an air-permeable insulation like fiberglass batts involving unvented rafters. It's also a bad notion, mainly because moisture can accumulate on your roof sheathing if you are attempting this process, and you may end up having sheathing rot.