Factory-adhered polyiso/OSB over rafters
A number of products are on the market that consist of polyiso foam insulation adhered to OSB. The manufacturing process looks to be one of the foam being sprayed directly on the OSB with no glues involved. Can this product be laid down on top of the rafters and screwed in place? Or is it required to have an OSB or plywood deck first?
i.e.: Drywall, rafters with cavity insulation, Hailgard, roofing paper, standing-seam metal panels
In a house with lots of cathedral ceiling building, an unvented roof seems quite reasonable. Laying down this combination insulation/nailbase product would not only provide a fully adhered closed-cell foam on the first condensing surface, it would provide a thermal block over each rafter. The rafter space could then be filled with foam board, glass batts, or other insulation. But all the insulation would be under the roof deck.
如果使用蒸气渗透的屋顶纸，将其进入OSB甲板进入OSB甲板的任何水分都可能干燥。然后在那个站立上的立式缝制金属屋顶，在那里，现场接缝面板将屋顶甲板放在3/8英寸的屋顶甲板上。
Any moisture that made it into the rafters could dry to the interior if a vapor permeable cavity insulation were used along with drywall for the ceiling.
例如，Hailgard仅指出它应该像其他任何OSB一样被铺设。如果这意味着它可以直接放在after子上，那就太好了。但是它是否符合代码，这会轻易卖给检查员吗？
- 巴利菲尔德
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Replies
AJ's right, you'll have to check with your local inspector and run it by the manufacturer first. Bring them into the conversation earlier rather than later.
But I think your building science is fairly sound, re: the vapor open (but airtight!) layers and drying potential. Couple things: I wouldn't use more foam in cavities - blown fiberglass or cellulose, being vapor open, would be a somewhat safer bet there. More importantly though, what's your climate zone and planned thicknesses of the foam sandwich and framing/cavity layers? It's the ratio of the R-values of these that determines your first condensing surface, and thus how critical the drying potential is.
We are not your building inspector nor are we the manufacturers. Direct your inquiry appropriately.
There are standard tables that building engineers use to figure shear. Your products are not standard. So to get from your idea of using said products to OKs from others to build is such that you need to make the inquiries.
Let us know the answers.
Arthur,
If you want to install an insulated panel directly on top of rafters in a new-construction situation, you should use structural insulated panels (SIPs). These consist of a layer of rigid foam sandwiched between two layers of OSB.
钉子面板与SIPS不同：它们由一层刚性泡沫组成，仅在一侧有OSB。钉子面板用于改造情况；它们通常安装在现有屋顶护套的顶部。