非典型大教堂绝缘
Hello,
我在气候区5A中，并试图确定如何在农场/商店杆型建筑物中最佳隔离大教堂天花板（图片附加）。建筑是多用途的大部分未绝缘，但我想将阁楼部分分成两半，并为绝缘车间使用一半。定期加热大约60-65°（但在全冬季冻结水平以上）。代码不适用于此建筑，但我不希望长期滋润问题。
Building has seam-taped ZIP roof sheathing with ribbed metal roofing, and 2×8 purlins 24″oc installed cross-wise between main post-frame “bays” instead of standard truss design. Building has ridge vent/copulas, and the half of loft that would remain un-insulated allows fresh air in through large vent area under lean-to “wings” (but not a tradition soffit).
在鸽舍的一半，我想要隔离，我已经安装了“衣领联轴”，以创建一个小的“阁楼”空间（连接到未绝缘的阁楼区） - 因此，任何天花板穿透（照明等）都将被限制在上面通风的区域。但是，从主建筑物的开始到这些“衣领关系”的主要建筑物的开始，有16个'的天花板上，这是由于PURLIN配置无法排出。
I have R-19 fiberglass and 1″ and/or 2″ foam board handy. Spray foam is out of reach due to cost. What combination would be safest for moisture? Foam against the sheathing (edges sealed) and fiberglass under? Or 1″ air gap under sheathing, fiberglass, and then seam-taped foam board for air barrier and thermal bridging? Foam sandwich? Since the 24″oc cavities are well sealed by the ZIP sheathing, and are closed on each end, air movement should be very limited inside. There also shouldn’t be any significant sources of moisture in the insulated space… although animals will be kept in some areas below, loft floor will be insulated & have vapor barrier, and lower portion of building is well ventilated to the outside.
I’ve read the cathedral ceiling guide, and understand best practices, but seems its primarily meant for living spaces with more standard construction, and don’t know what to make of my situation. Thanks for any guidance you can provide!
GBA Detail Library
由气候和房屋部件组织的一千个建筑细节的集合
答复
Is there enough headroom to build a "building within a building", rather than trying to insulate between the purlins?
In zone 5A if you built the "roof" of the inner building so that by the purlin bays above you could even use housewrap as the exterior side air barrier to the insulation layer and it will easily dry into the building that surrounds it, no need for vapor retarders. Nail up some 2x4 furning laid flat and perpendicular to the underside of the purlins to establish a vent gap continuous with the interior air of the main building. With 3" foam board (any type) in a continuous sheet below your 2x furring you have sufficient dew point control for install R19s in 2x6 rafters of your inner building.
如果您将其限制为2“泡沫，请为椽子上方的R19S进行外侧空气屏障，并将泡沫盖在侧面上的泡沫。然后，您可以拧紧1 x毛茸茸的安装天花板石膏或长拧到椽子上。
Thanks for your reply. I had briefly thought of something like that, but 2 issues come to mind... first is that there's no "soffit" to admit fresh air at the bottom in the area I'd like to insulate (for each "bay" the void between building within building would just be connected to ridge vent at top, and second, with the amount of additional lumber required, I'd be well on the way to layer of spray foam in terms of cost. Any thoughts on ideas I mentioned, or all too risky? My feeling is that if I did insulate the existing cavities and did cap nailed taped seam foam underneath, combined with ZIP roof, I would have relatively low risk for air movement in assembly.
Matt,
在您的情况下，某种类型的切割和鹅卵石方法可能是符合您要求的唯一方法。以下是关于主题的文章的链接：Cut-and-Cobble Insulation.
In Climate Zone 5, the foam layer needs to have a minimum R-value of R-20 before you switch to a fluffy insulation like fiberglass.
It's up to you to decide whether you want to break the rules -- but if you do, do so with your eyes open, aware of the risks. If your rigid foam layer is less than R-20, the risk of moisture problems increases (a) if you decide to heat this space for longer and longer periods during the winter, and (b) if any moisture-generating activities occur in this space.
谢谢马丁，我会看看我是否可以拿出任何其他东西，但可能需要重新开始。欣赏反馈。