带金属屋顶的小房子：蒸气罩？
I’m building a 20’ tiny house on a trailer with a 3:12 shed vented roof vented. My current plan for the roofing and ceiling structure consisting of 2×6 rafters is as follows: metal roof->water and ice shield->5/8” plywood->XPS foam between rafters->tongue & groove beetle kill planks. I am located in zone 5b with cold snowy winters. Is this layering plan sufficient to prevent condensation issues in the winter? The question is, do I need a vapor retarder between the plywood and xps foam, or between the tongue and groove and the xps, or skip a separately distinct vapor retarder? Thanks for any insights you can provide – I am a complete rookie. For what is worth, the heating will be small wood stove.
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答复
对不起，我的帖子中的图层错过了T＆G和框架之间的1“XPS。
User-6887032,
为了安全，这种类型的屋顶组件需要在最上层的绝缘层和屋顶护套之间的通风通道。通风通道需要连接到屋檐附近的拱门通风口和峰值附近的脊通风口。
所选择的方法称为切割和鹅卵石方法 - 通常不推荐用于屋顶，如果有清晰的通风通道，可以购买。有关更多信息，请参阅Cut-and-Cobble Insulation。
By far the most important layer in this assembly is the interior air barrier (needed to prevent interior air from entering the assembly). Note that tongue-and-groove boards are extremely leaky. In theory, a continuous layer of XPS between the boards and the underside of the rafters could be used as your air barrier, as long as the seams of the XPS are carefully taped with high-quality tape -- but some experts note that XPS may shrink, pulling away from the tape.
For more information on XPS shrinkage, seeUsing Rigid Foam As a Water-Resistive Barrier。（向下滚动到读取“DO刚性泡沫面板缩小的子标题下的部分？”）
问：“我是否需要胶合板和XPS泡沫之间的蒸汽延迟器，或在舌头和槽和XPS之间，或跳过单独不同的蒸汽延迟器？”
答：不，您不需要额外的蒸气延迟器，因为XPS已经是蒸汽延迟器。你需要的是持久的空中障碍。
嗨马丁，
感谢您的快速反应。注意到内部的空气障碍。是否有比泡沫板更好的选择？此外，我试图在移动结构时，由于振动问题，我试图远离干墙。我不是100％的舌头和沟槽的需要销售，也可以对胶合板护套内部而不是T＆g的想法开放。
I just read your suggested links and I'm now wondering if I should consider roxul instead of foam board in the roof due to the shrinkage issue and PITA install factor. I unfortunately can't get a spray foam installer up to my location and I'm leery of trying DIY spray foam options.
Best,
j
User-6887032,
Can you tell us your name?
一旦包括通风通道和挡板，您的2x6椽子有足够的空间约4英寸的绝缘。如果您使用切割和鹅卵石的方法安装矿物羊毛绝缘或约R-20，那么这并不多 - 关于R-16。连续的内部XPS添加另一个R-5，因此您最终得到R-21至R-25。这远远低于最低代码要求。
The inferior R-value may not matter in a tiny house, because a tiny house is usually easy to heat, but it's still worth mentioning in case you were unaware of the issue.
对于内部空气屏障，首选总是录音干墙。只要您不担心未来的泡沫收缩，录音XPS就会起作用。另一种选择是欧洲空气屏障膜之一（例如，Intello Plus).
Thanks again Martin! My name is Jon, but I unfortunately haven't figured out how to change my name on this board.
Intello Plus does seem like a good option for my needs.
鉴于一个小屋将从内部乘员，淋浴，烹饪等中有更多的浓缩水蒸气创造，我也应该寻找一个屋顶界面，这些界面提供比优雅的水和冰盾更高的渗透率吗？我意识到金属屋顶具有基本零渗透性，因此界定的渗透性可能较少令人担忧？
j,
Q. "Given that a tiny house will have more concentrated levels of water vapor creation from the inside occupants, shower, cooking, etc., should I also be looking for a roofing underlayment that provides a higher level of permeability than grace water & ice shield? I realize a metal roof has essentially zero permeability, so maybe the permeability of the underlayment is of less of a concern?"
答：你不会通过金属屋顶造成任何向外干燥，因此您的屋顶衬垫的渗透率无关紧要。
Roofs don't dry toward the exterior, metal roof or no, so don't bother with permeable underlayments.
By the time you've paid for the cut'n'cobble foam a Intello you will have been better off buying a few sheets of 3" or 4" reclaimed roofing polyiso and installing R23 rock wool or R21 fiberglass in the 2x4 bays and go un-vented. A 4x8 sheet of used 3" polyiso in near perfect condition usually goes for between $15-25 in my neighborhood, 4" goes for $20-30/sheet, sometimes less. Double-layering it with 2 layers of 2", seams overlapped works too. With 4" foam the you'll need 6" pancake head timber screws to hold it all down with an OSB nailer deck onto which you would mount the roofing, at about 75 cents per screw in small quantities, eg:http://www.diyhomecenter.com/fastenmaster-headlok-heavy-duty-wood-screws-50-box?screwlength=34。（咨询Nailbase制造商的安装指南，以获得最佳螺钉图案和间距，例如：https://www.hunterpanels.com/docman-类别/ product-documents/hpanels/speciality-products/1388-h-shield-nb-application-guide/file.)
4英寸的Polyiso（R24-ISH在完全评价的R）和R23摇滚羊毛在椽子湾，你仍然会害羞R49，但它仍然会在U-Factor的基础上达到代码性能。在贬低的R5 /用于露点控制评估的英寸您仍然将R20脱离R43，占结构护套外的总R的约47％，即使在较高的湿度下也是5个气候的大量气候。（对于40％的普通房屋，即使是40％的常规房屋通常就足够了。）仅3英寸的外部PolyiSo，腔内R23岩棉可能有点边缘，但R20或R21玻璃纤维仍然可以。