如何在1.5层斗篷中隔离the子以减少热桥梁？
Hi All,
I live in a 1.5 story cape in Nassau county on Long Island (zone 4a). The house is a fairly typical
没有添加性的供应，这意味着几乎没有关注隔热材料的空气密封要少得多。正如住在其中一所房屋中的任何人都可以证明的那样，二楼在夏天扼杀。我们有一个地热加热/冷却系统，管道贯穿膝盖。
I currently have little to no insulation in the rafter bays. What exists is a combination of “fluffy stuff” (fiberglass, rock wool, and even cotton). I want to address the overheating issue, but more importantly want to do it in a way that respects my carbon footprint. After much research, it seems like a hot roof is the way to go. I have been considering open-cell water-blown spray foam to fill the rafter cavity (rafters are 2×6), but I woul like to address thermal bridging, air seal, and bring my attic insulation level to > r38. My question boils down to this: how do I do it? I’ve considered the following:
1.喷洒整个屋顶甲板，用开放的牢房充满腔。建立一个像a子一样抵消after子的穆尼壁状结构，并用网覆盖（和绑带？），充满纤维素。
2.与上面相同的喷雾剂，但用几层polyiso覆盖泡沫。皮带和石膏板。我知道Polyiso的GWP可能很高。
3. Same spray as above, fur out the rafters, cover with polyiso, fill the remaining cavity with cellulose. I’m not sure this will work, as it seems to me that the netting allows for air to escape as the cellulose is being filled. Polyiso is not air permeable.
任何想法都非常感谢！我想做这个项目，但也对我们的环境负责。谢谢！
账单
GBA细节库
A collection of one thousand construction details organized by climate and house part
Replies
连续的polyiso护套的全球变暖潜力并不大得多（可能小于after子之间的开放式牢房，而after子之间的开放式牢房的性能则不高。每立方英尺的聚合物是2倍，但性能较高，而不会被after脚削弱。after架之间的R20腔填充在热桥后约为R13-14，每平方英尺约2.3磅（平均，包括框架分数）。为2.3磅/r14 = 0.16 lbs/r-ft^2。
With 1lb/ft^3 polyiso you get about R6 for 1/12= 0.083lbs for 0.083/R6= 0.014 lbs/R=ft^2, a full order of magnitude improvement.
Polyiso（Pentane）的吹动剂的GWP约为7倍CO2，而开放式细胞泡沫（水）的吹剂可以忽略不计，但是这根本无法弥补每位聚合物的差异。
但是，您不能在没有产生高风险的水分陷阱的情况下在未通风屋顶组件的内部使用Polyiso。
If you install if closed cell foam blown cellulose between the rafters, install a sheet of smart vapor retarder there and add Mooney-style 2x6s perpendicular to the original rafters 24" o.c. you can then install R23 rock wool on the Mooney-inteiror-purlins with only without any roof-rot risk. You could also put the membrane on the interior side, directly under the gypsum if your installer thinks they can still dense pack it. The flash-foam of closed cell puts a ~1 perm vapor retarder between the cellulose and interior and creates a non-wicking condensing surface, which will protect the roof deck. The variable vapor retarder limits the amount of moisture that the cellulose has to buffer to very reasonable levels, while allowing reasonable seasonal drying rates for the cellullose.
威廉，
本文解释了您可以隔离倾斜屋顶组件的所有各种方式：如何建造绝缘大教堂的天花板。
到目前为止，最好的方法是在屋顶甲板上安装一层厚的刚性泡沫。当然，这种方法并不便宜，它要求您安装新的屋顶 - 但这是最好的方法。
4A区的IRC代码分析为R49。带有2x6 afters和岩石羊毛棒（R23）和5英寸的外部polyiso（名义上的R30，在降落之前），即使在降低了临时，您也将拥有足够的外部R。大约R43名义上，但是由于afters的热中断，它仍将以U0.026代码最大每个表N1102.1.3的U0.026代码下方符合代码。
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_11_sec002.htm
The installed cost of that much polyiso is on the order of $3 per square foot (plus the cost of new roofing) with virgin-stock foam, about half that if using reclaimed roofing foam from commercial demolition. For performance-prediction purposes presume polyiso will average somewhere between R5- R5.5 per inch with that stackup, in your climate. So the 5" of exterior foam is a bit under R25 during the coldest weather, if R30ish during the spring & autumn shoulder seasons. If installed on the interior side of R23 rock wool it performs at it's full rated R, but you'd have the moisture trap problem.
如果夏季热量是问题，那么所用材料的热量就会变得重要。在内部有像石膏纤维板（Fermacell）这样的重型材料，而不是轻质板岩，这是一个令人惊讶的差异。使用密集的包装纤维素代替玻璃纤维或岩石羊毛也有帮助。
快速假设,试试这个德国计算器with different materials etc - look at the heat protection values at the top right. Any questions, just email me, their English translation is far from complete. Phasenverschiebung = phase shift in hours, temperaturamplitudendämpfung = temperature amplitude damping.
https://www.u-wert.net/berechnung/u-wert-rechner/index.php?&d0=1.25&L0=1&mid0=196&d1=4&L1=1655634327&mid1=217&x1=10&uu1&d2=4&L2=1655634327&mid2=36&x2=6&uu2&d3=4&L3=1655634327&mid3=217&x3=34&uu3&d4=0.02&L4=2&mid4=2970&d5=14.5&L5=1603385292&mid5=551&x5=70&d6=14.5&L6=1603385292&mid6=36&x6=11&d7=1.9&L7=6&mid7=17281&d8=12.5&L8=3&mid8=3287&bt=1&T_i=20&RH_i=50＆te = -5＆rh_e = 80＆外部= 0＆name = dach