添加纤维素绝缘材料在现有R-19的顶部
Robert King|Posted in一般的问题on
我的建筑商R-19玻璃纤维insulatio安装n (with vapor barrior) in the attic of the 2000 square foot one-story house he is building for me in Maine. He now plans to add 13-14 inches of blown Green Fiber cellulose insulation on top of this. Cellulose insulation being as heavy as it is, my concern is that it will compress the fiberglass, diminishing its loft and hence diminishing its R-value. Does anyone have any data on the relationship between compression and loss of R-value with fiberglass insulation? Or on the question of how much such a layer of cellulose would compress the underlying fiberglass batts? If this could be known, the cellulose layer could be increased in depth to compensate for the R-value loss.
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答复
在新建筑中，我认为人们只会使用纤维素。您的建筑商正在做的是，当房屋已经建造并需要更多时，我们如何添加绝缘。
关于您的问题，压缩玻璃纤维的R值每英寸较高，但现在厚度较小。不用担心。纤维素是一个好处。继续写支票给建筑商。
罗伯特，
这里唯一的谜团就是为什么您的建筑商曾经安装了玻璃纤维棒的原因。如果他足够聪明，可以建议纤维素绝缘，那么他应该刚刚安装了100％的纤维素，没有玻璃纤维，如A.J.著名的。
一旦安装了玻璃纤维巴特（无论是故意还是错误地），就决定用纤维素覆盖玻璃纤维棒的决定是一个不错的选择。玻璃纤维棒有几个缺点，用纤维素覆盖这种阁楼是一种标准解决方案。
但是，我希望您的建筑商记得在安装任何绝缘材料之前在天花板飞机上进行仔细的空气密封工作。
纤维素可能会稍微压缩玻璃纤维棒，但这种压缩的潜在缺点远远超过了添加的纤维素的优势。当压缩玻璃纤维泡沫时，巴特的R值略有下降，但每英寸的R值增加。我将附加一个图表，该图表显示玻璃纤维棒的压缩与R值之间的关系。[点击图片放大。]
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r19 batt与R13 batt的材料相同，只是绒毛蓬松。将其压缩到3.5“ 6.25”（制造的阁楼）仅是R5的“损失”，但是现在较密集的纤维的空气率改善使其在极端温度下的工作状态更好。
Focusing on the total post-blown depth of cellulose + fiberglass is the right way to approach it, since the slightly compressed R19s and cellulose will have about the same R/inch.
笔记that in the compression charts an R19 batt only performs to R18 when installed in a 2x6 wall cavity, and performs at R13 when compressed into a 2x4 cavity. Labeling it R19 is somewhat deceptive since the most common application is in 2x6 framed walls, and is why R20 wall cavity insulation is specified in newer versions of the IRC, not R19.