Spray Foam in Cathedral Ceiling and Attic Floor Joists question (New Construction)
大家好，我正在北弗吉尼亚州（第4区）建造新房，建造者刚刚完成安装窗户。
We are now in the Insulation phase, and the builder just told me what the insulation company is planning to do around the home.
I have read a lot of articles on GBA and other websites about Open/Closed Cell and techniques but apparently what they just told me seems to be the opposite of what I found on this site.
这就是他们打算做的：
Exterior walls (2×4): 3 1/2″ of Open Cell
大教堂天花板（2×4屋顶桁架）：带通气通道的10英寸开放式牢房，或密封无通风
阁楼地板（2×4）：1英寸的闭孔和10英寸的纤维素绝缘材料（我的HVAC不在阁楼中，仅在阁楼中运行）
地下室（浇注混凝土和2×4）：3 1/2开放式牢房
如果我错了，请纠正我，但他们真的很困惑我。For what I’ve read online, it seems that on both Cathedral Ceilings and Basement walls the standard is Closed Cell because it’s a vapor barrier, so when I mentioned it they said that I can run a perm test on my basement walls, which I find ridiculous because this is a brand new home, and the moisture level could be different in 5 years from now.
Same with the Cathedral Ceilings, they said that if I Install the ventilation channels I will not have any moisture issues caused by condensation.
I also seriously don’t like the idea of having all that blown cellulose in the roof, it’s an unfinished space but at the same time I don’t want it to be messy, you never know if an animal find its way in there and also the cellulose is not water proof.
你们有什么感想？我真的很高兴能对此发表一些专业意见！
Thanks!
GBA细节库
由气候和房屋部分组织的一千个建筑细节的集合
Replies
仅适用于入门者...墙壁上的开放单元3-1/2“是R-14或15？代码需要什么？
I'd tell these guys to stop the presses completely until you decide how you want it handled.
谢谢大卫，该代码需要在墙壁上R13和天花板中的R38。
They are using SEAL PRO 500 Spray Foam Insulation.
I'm in zone 4a in WA state and the requirement is R-21, so almost all walls are 2x6.
很难想象为什么要从能量的角度使用最低代码的房屋。只要您拥有房屋以及此后的其他人，这种选择就会使您付出代价。如果我已经有2x4墙，我会在螺柱舱中搭配纤维素，在护套外面有2英寸的泡沫。
Alternatively, go with closed cell in the walls and get roughly R-21.
在阁楼上有管道意味着您希望它们非常密封和绝缘，或者要隔离屋顶而不是阁楼地板。
It might be difficult to convince them to add exterior foam -- unfortunately, it is still pretty radical in many parts of the US.
这可能是隔离墙壁的最佳方法 - 螺柱托架中的外部泡沫和纤维素。
请参阅有关屋顶和墙壁如何工作的播客/文章：
//m.etiketa4.com/blogs/dept/building-science/perfect-wall-roof-and-slab-building-science-podcast
Cellulose is a great choice for the attic, though if the ducts are up there, you should consider moving the insulation up to the roof. See this article://m.etiketa4.com/green-basics/vented-or-unvented-attic
担
谢谢大家，这里没有像西澳大利亚州那样感冒，这是用2x4建造的标准，但是幸运的是，我们将砖块放在外面，到处都是，这肯定会有所帮助。
What I'm really trying to figure out is why would they tell me to use open cell in the basement and cathedral ceilings when on this site and other sites, all I've read is the opposite (closed cell)?
Giuseppe,
您询问为什么您的安装程序建议在大多数区域推荐开放式泡沫。答案仅仅是它比闭孔泡沫便宜 - 如果您的预算允许，我相信他会很乐意喷涂您的规格。
We install foam insulation in zone 5 and have used both open and closed cell in roof decks for years with very good results. Venting is nice but not required, especially since your painted drywall will form an interior vapor retarder.
Below grade, we prefer to spray about 2 inches of closed cell foam because of its moisture tolerant properties. At 2 inches, the perm rating is around 0.6, which will allow some drying to the inside. If you never have an issue with excessive foundation moisture, open cell foam will work fine.
不需要将一英寸的闭合牢房放在阁楼地板上。您想要空气屏障中有孔的泡沫，例如在内墙和固定装置上，但是即使没有泡沫涂层，一片干墙也是完美的空气屏障。纤维素作为阁楼绝缘效果很好。我们吹18英寸，R-60。与全泡沫系统相比，这节省了房屋所有者的钱，可以更好地使用其他地方的升级选择 - 例如，在2x4墙中，闭孔泡沫到R-20。
Thank you for choosing foam and good luck with your new home!
谢谢Torsten的评论，如果您不介意，我想问一个问题。关于大教堂的天花板，您宁愿安装闭孔泡沫还是开放式电池？正如我之前提到的，他们还正在安装通风通道。
You are welcome Giuseppe. The vent channels will remove any lingering worries you might have about moisture control with the open cell foam and either will work well. Other than cost, I don't think that there is any advantage to using open cell over closed cell but if you can achieve the r-value that you are after with the lower cost product, why not use it?