Shingle Sidewall
Hi
Working on a detail with a builder to add 1″ of polyiso to the exterior of an existing 2×4 wall in Zone 5.
计划将雪松单打作为侧壁材料。大多数情况下，似乎排水层（水控制层）在泡沫后面（B/W泡沫和护套）。但是，我们想将排水包裹用作空气控制层，其附加优势是提供带状疱疹后面的较小（非常小）的排水空间。
Any issues with placing the drain wrap b/w the shingles and foam as opposed to installing the housewrap between foam and sheathing?
Happy New Years!
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Replies
No problem with having the WRB on the exterior of your foam. However, 1" of polyiso in Climate zone 5 is insufficient exterior insulation. If you search the site there are numerous articles on how much insulation is needed, as well as integrating a WRB into your system.
克里斯，
我不同意亚伦在气候区域的1英寸Polyiso（R-6）是否足以适合2x4墙的问题。刚性泡沫足够厚。有关更多信息，请参阅Calculating the Minimum Thickness of Rigid Foam Sheathing.
There is a more important problem to your plan, however. I don't recommend installing cedar shingles on rigid foam. Since the shingles won't be able to dry quickly on the back side, they will tend to curl and split if you nail them over foam.
带有外部刚性泡沫的房屋上的通常方法是（a）在泡沫上安装一层OSB或胶合板（某些构建者使用钉子），或（b）在水平1x3绑带上安装Cedar带状疱疹。
如果您选择在泡沫上安装胶合板或OSB，则最好的安装方法将包括三维排水垫，例如Cedar呼吸。
Apologies, I had the 7.5 number in my head. Sorry to get off tangent but what is the reasoning behind lower R numbers on 2x4 walls?
亚伦，
如果您建造带有外部刚性泡沫的木结构墙，则将墙壁护套夹在两层绝缘层之间。护套的温度位于室外温度和室内温度之间温度的连续性上。
The thicker the wall framing (and the thicker the insulation installed between the wall studs), the closer the wall sheathing is to the outdoor temperature. In other words, if you have 2x6 walls, the sheathing will be colder in winter than if you have 2x4 walls -- unless you make the rigid foam thicker.
马丁，
Would you have the same concerns with cedar shingles directly over housewrap or felt?
Just wondering if you see a specific difference when foam is included...
谢谢
最低限度的最佳练习是在“排水包裹”的房屋包裹上安装雪松木瓦，在这里通常称为Crinke Rap。正如马丁所描述的那样，雪松呼吸器是更好的，但是它很昂贵，根据我的经验，后方有点痛苦。
克里斯，
Aaron's answer is correct. But if you install cedar shingles over a layer of asphalt felt, and if the asphalt felt is installed over a layer of board sheathing or plywood sheathing, then you have some moisture-buffering capacity in the asphalt felt and the sheathing. There materials are hygroscopic, and can therefore take on moisture when the shingles are wet. This is useful.
On the other hand, rigid foam can't take on any moisture at all. That's why rigid foam is the worst possible substrate for cedar shingles or any wood siding.
嗨，马丁和亚伦，
感谢您的回复。我们通常在侧壁上使用雪松呼吸器。它是如此昂贵，我打算将排水包裹定为替代方案。
In our coastal environment, we have been getting 25-30 yrs. out of cedar shingles over felt. I have wondered how many years you gain with cedar breather. Is it 5 or 10? Just wonder if the upcharge for the product is worth the long term benefits? I suppose the drainage space is not just beneficial for the siding, but for the substrate as well. But still wonder if there is truly a equal benefit to the cost difference.
谢谢as always.
马丁和吉尔，
我处于同一气候区域，但从技术上讲是区域5。我计划在胶合板和船舶墙护套上使用沥青感觉，以取代需要更换的雪松侧壁带状疱疹。这种方法无法解决缺乏空气障碍。我们将在里面放板岩，这是否有资格作为空气屏障？或者我还应该做其他事情来制造空气障碍。由于这是一种重塑，只要它不会引起问题，我就可以简单地更换沥青毛毡而只有蒸气屏障。