I don't have practical experience setting up inside the Carribbean or creating metal properties, so I am not the most effective particular person to comment. But here are a few reflections:
The most effective method is to do all the work without delay: rigid foam above the roof sheathing (as advised inside the post), and fluffy insulation beneath.
Really should I exploit airtight baffles or not, I don't see a means to have dampness escaping in a assembly with airtight baffles, fiberglass and xps on The within, it doesn't matter what the dew stage are going to be inside this assembly And maybe build condensation that cannot evaporate devoid of air flow.
In the course of the summer, roof ventilation isn't going to appreciably decrease the temperature of asphalt shingles or other kinds of roofing.
I wish to correctly insulate my cathedral ceilings and was wondering to spray two inches of shut cell foam to sheathing, then fill with dense packed cellulose. I'm asking yourself if I can connect craft paper and pine paneling to the 2x8 rafters and after that fill the bays with cellulose.
Many thanks - This really is new development, I'm the designer / builder, and the greater I examine it, I'm liking all rigid - considerably less fussy. The best layer of rigid above fluffy makes my eave far too thick in any case. The air barrier for that T&G ceiling is actually the sandwich of felt and taped three/eight" CDX.
If you need to use rigid foam, the best spot to set it truly is along with your roof sheathing, not less than your roof sheathing.
To adjust to the code -- also to adopt a creating system that is a lot less risky -- you have to both involve ventilation channels or you need to put in a layer of spray foam to the underside of your roof sheathing, adhering to the tips described from the article on this webpage.
Below the 2x8 pine T&G, There's nine" of beam exposed, but we have only 4†or at the quite utmost five†to Engage in with, mainly because at the very best of your stairs which ascend the side on the area, the ceiling is scarcely earlier mentioned a tall human being’s head as it is actually. Also, link we want to take care of an uncovered beam profile to the aesthetics. I hope the attached photos illustrate the problem. I believe an unvented roof assembly is the only real likelihood here, as the best issue from the cathedral ceiling is not the ridge from the roof.
Yesterday we blew the insulation and set up the SIGA Majcoat on the CAPACES Management Institute. There was more than eight,000 Cubic toes of insulation to set up, so our insulators had two of their blower vehicles and an excellent crew on internet site. They were being blowing cellulose as rapidly as they could and also the the rain was heading our course. Below forty five minutes after the insulation was concluded we experienced finished the Majcoat and were being occupied taping seams.
Many thanks Martin - reference Now I see why my unique prepare for any SIPS envelope was so elegantly very simple. It appears like min R-ten sprayed beneath the roof sheathing after which a complete-fill in the bays with batt / fluffy, in addition to a vapor sealed drywall lid can get me the 'scorching' (unvented) roof process the SIPS was within the get go.
The easiest method to move forward would be to choose a far more vapor-permeable sheathing material -- a thing like fiberboard.
As your home flexes with changes of temperature It really is attainable, even most likely that a few of the foamed-in air sealing will leak. It'd be value carrying out two" of open up cell foam on the inside side of which would be a far more versatile and trustworthy long lasting air seal.
I am opening up my household and putting in cathedral ceilings, I just desired to substantiate my approach due to the fact I my explanation obtained 2nd feelings reading through An increasing number of about it. My original final decision was to go with a vented roof method and R38C batts. I browse a whole lot about the different solutions and it however appears to me this is the best. Livint in Atlanta GA We now have to cope with both equally incredibly hot humid summers and cold winters, so humidity Handle is an issue, This is why I believe the vented approach is the best. Anyhow, I am right down to the rafters and roofdecking and furred out the prevailing 2x6 with 6" metallic studs, so I've about 11.5" for insulation. Mt strategy was to create a continuous ventilation beneath the roofdeck, my query goes in the direction of to implement baffles, xps board Make baffles or insect screen nailed at furring strips to allow for that airspace.