Installing a roof over unvented attic/cathedral roof?
ARMANDO COBO|Posted inGreen Building Techniqueson
我们正在就非通风屋顶组件的最佳安装细节进行辩论。CZ4B
1.一个部分是在带2×8 afters的大教堂天花板上，开放的细胞泡沫，另一部分是阁楼空间和开放的细胞泡沫。总数：R38+
2.我们同意在屋顶护套上使用1英寸的刚性泡沫进行热桥。
3. We disagree in installing a second sheathing on top of the rigid bd.
4.我们不同意屋顶材料：带状疱疹与金属或瓷砖。
Are there any shingle manufacturers that allows shingle roofing installation over an unvented roof assembly?
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Replies
不幸的是，现在有很多制造商（我很确定）现在这样做 - 不是因为它对木瓦的耐用性和寿命没有影响，而是因为担心越来越多的“绿色”部分的市场份额失去市场份额房产市场。
Thanks Robert. I should have mentioned my roof details: shingles, Triflex VB, 7/16 sheathing, 1" rigid insul. R7, 5/8 Sheathing, 7.5" open cell. Builder/Owner dosen't want to install 2nd sheathing and thinks he has to use metal or tile over nonvented roof assembly.
对不起，错字：1“ Insul是R10
What type of rigid insulation has an R-value of 10?
Armando，值得怀疑的是将您的护套夹在不可渗透或大部分不可渗透的层之间，当我们都知道（1）（1）（1）一定量的水分会通过带状疱疹泄漏，并且（2）护套是否在水上和水中分解不能干燥。
Armando,
如果您在after子之间喷开敞篷泡沫，屋顶组件将能够干燥到内部（当然，您不会安装内部聚乙烯） - 因此，我不必太担心在您的情况下，“泡沫三明治”问题。
硬质泡沫塑料越多你买得起的roof sheathing, the better. One inch isn't much. And 1 inch of rigid foam certainly isn't R-10. If it's polyiso, it's about R-6.5.
您可以在刚性泡沫上使用所需的任何屋顶。金属屋顶或瓷砖可能更容易，因为您不需要在刚性泡沫顶部的第二层胶合板 - 仅1x3或1x4平行于山脊。如果您安装沥青带状疱疹，最好的方法是在泡沫顶部安装2x4钉子（在after上方的每个2x4上方，为了允许拱形到摩托车的通风），然后是胶合板，沥青毡和带状疱疹。
感谢您的所有答案。带状疱疹是与房屋建筑风格一起使用的“板岩”木瓦。NM中的真正板岩太贵了。三明治细节来自GBA.com和BSC。我们之前已经使用了金属和瓷砖屋顶，但没有带状疱疹。开放的牢房对内部干燥，不用担心，而且我们也有空气供应阁楼。良好的屋顶密封和良好的VB应该照顾毛细管。我进行了屋顶组装分析，1英寸的刚性泡沫对我们的气候有益。
By your answer Martin, can you install shingles directly over 1"+ rigid foam? Regular fasteners? That’s my only concern.
Armando,
不，您必须拥有胶合板，OSB或板护套。
我同意马丁的分层处方（请注意，他建议感觉到而不是聚合物的底层），但不同意他的确定性敞开的泡沫可以使内部有足够的干燥。
There is a great degree of variability between various foam products in the ratio of open to closed cellular structure, and of course it's the actual application that determines the ultimate qualities of the material.
即使是塑料泡沫的强烈拥护者的BSC，也警告其渗透性桌上“虽然所有喷雾泡沫非常适合空气密封，但它们的密度通常很大，其密度很大，R-value，R-Value，吹气，防水性，蒸气通透性。这最后两个对您如何在各种建筑物组件中使用喷雾泡沫的方式产生最大的影响。”
They list 3½" of Icynene as having a perm of 16 (the company claims 24), which would be about 7.5 perm for a 7½" installation. But BSC also notes that Icynene absorbs 34% of its volume in water when soaked. Once a hygroscopic matrix, like open-cell foam, becomes saturated, it loses its vapor permeance (which requires open lumens). In other words, it works like a sponge.
And do not forget that water vapor permeance is only one part of the equation - diffusion is an energy-driven process. The more thermally insulated an assembly, the less heat flux, the less vapor drive. And the salutary tendency toward roofings with a higher albedo to reflect solar radiation also dramatically reduces heat flux through a roof assembly.
由于扩散并且感觉不是100％的VB，这就是为什么我们使用更好的VB产品，是的，我的水分管理细节很好，我知道构建器将在安装方面做得很好。Ashrae基本面，15磅的沥青毡的湿杯渗透率为5.6，焦油毛毡为18.2 perms。
刚性泡沫是第二层的水分屏障，因此我预计不会有任何水分进入大豆的开放式牢房。另外，我在阁楼上有通风，房屋处于干燥的气候下。
In forest areas, vented roofing or cladding are highly discouraged; in some municipalities in the Southwest, they are not allowed.