Redundancy of Vapor Retarder and Latex-Painted Plastered Blueboard for Vapor Retarder
Climate zone 6.
My wall stackup from the exterior is 1″ hemlock siding, 1″ airspace, housewrap, 2 1/2″ xps, 5″ studwall insulated with r23 roxul.
I understand that the 2 1/2″ xps is marginal for my climate zone and detailing the vapor retarder will be essential to performance.
我将安装蓝板，这将被涂抹，灌输并用乳胶涂料涂漆。
如果蓝板详细良好，是否有必要甚至是良好的保险，以便在蓝板之前安装汽室延迟器，或者如果是井详细说明，那么它将是不必要的冗余吗？
For that matter, are there any issues with two layers of vapor retarder?
Thanks, Daniel
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答复
丹尼尔，我会首先要注意，普通读者可能厌倦了看见，但无论如何我都要提到 - XPS中的吹风剂是有效的温室气体，比二氧化碳1400倍，比任何其他施工材料更差。尽职尽责的建造者找到一种替代材料，具有较低的环境影响，如Polyiso泡沫，EPS泡沫，摇滚或木纤维绝缘。如果您可以找到使用XPS的源，这是一个不同的故事。此外，XPS的XPS宣传值R-5 /在时间上降低到约R-4.2 / IN，等于或接近EPS的稳定R值。
CZ6中具有蒸汽延迟外部保温的墙壁需要至少33％的R值，以保持露点的冷凝表面并避免水分积聚，允许涂漆的干墙，3类蒸气延迟器，全部这是在内部所需的。使用R-23腔绝缘，这意味着在外部至少R-11.5。2.5“XPS是标称R-12.5，但将年龄为约R-10.5。如果目标只是为了超过建筑官员，你会没事的，但我更愿意避免风险，要么碰到你的外部保温真正的R-12.5或更高，和/或在内部添加可变渗透膜，如SIGA MAJREX或PRO CLIMA Intello。我假设涂上薄型的撇灰岩石膏在蓝板上表现大约与干墙相同，但我可能是错误的- 这不是我在哪里。
The IRC building code simplifies the math to say that a Class 3 vapor retarder (i.e., painted drywall) is allowed if you have at least R-11.25 over a 2x6 wall, but some think their wording is a bit too simplified.
Depending on Daniel's construction schedule, he might actually be able to get the new Foamular NGX version of XPS that drops the GWP from 1420 to 80, still higher than the other options you list, but vastly better than blueboard. It's supposed to be available throughout north america as of Jan 1st. There's not much reason to prefer it to EPS, but it might be more readily available than EPS at some point--we'll have to see how quickly it's actually made available. Scott Gibson is working on an article on this and I'm hoping he'll have more detail than I know about how soon it will be available.
查理，这是一个很好的观点。我希望看到新XPS的生命周期分析。我最近经历了HFC VS HFO发泡剂的喷雾泡沫行业的生命周期分析，虽然GWP为1030 Vs 1，但HFO-吹塑的总GWP仅为HFC吹的24％。仍然更好，但没有一千次，因为你可能期望只关注吹药。我想起XPS相似，但希望看到数字！
Yes, I am not ready to start recommending it as a green choice--only as less of a disaster than it used to be. But it will be good to get more information.
Because of the valuable information I received on this forum, I accessed and used reclaimed xps for the entire project. Unfortunately at the time I went by the advertised r-value and also the reported cold weather performance of xps which claimed an increase in r-value as temperature decreased.
Short of removing all the siding, I'm stuck with the 2.5" xps.
Great that you got the reclaimed XPS!
达纳在它的方向上指出了我，在此之前，我从未听说过它的可用性。从那以后，我为我的新房子购买了整个披肩保温，另外150张3“×4'x3”回收的Polyiso，以及这里和那里的一些薄片。这一切都处于美好的状态，以及它所花费的一小部分。我当地的Craigslist始终有很大的数量。比巨大的储蓄更好地了解可能有一次注定垃圾填埋场的材料。
丹尼尔，R值随着温度的减少而增加，我相信除了Polyiso之外的所有绝缘。我不确定的程度。用了很好！
在您的边际案例中，使用II类内部侧延迟的高端（例如.5至1 PERMS）。例如，只是蒸汽延迟涂料。为此提供支持：
https://www.continuousinsulation.org/content/2021-ibc-and-irc-adopt-improved-vapor-retarder-requirements
更重要的是，总是空气密封并测试它。内侧有些更好。
Just to be clear, typical exterior foam doesn't keep the sheathing above the dew point or prevent condensation/sorption/moisture accumulation. But it usually does limit it enough to avoid problems. Even more so if foam is the only sheathing. Understanding this is critical to understanding why perms (both interior and exterior) still matter.
我本可以更精确和书面，“将冷凝表面保持在露天上方绝大多数的时间。”对于想要了解的人，你可以在这里读到这一点：
https://www.buildingscience.com/sites/default/files/document/ba-1406_measure_guideline_incoreting_thick_layers_of_exterior_rigid_insulation_on_walls_2015-04.pdf.
https://www.buildingscience.com/sites/default/files/migrate/pdf/BA-1316_Moisture_Management_for%20High_R-Value_Walls_rev.pdf
XPS是唯一的护套。
How is the assembly tested?
这里应该有一些信息：
//m.etiketa4.com/collection/air-barriers-sealing.
感谢您的信息。
My inclination is use vapor retarder paint. Is there any advantage or disadvantage If I also install Membrain prior to the blueboard?
Thanks, Daniel
编辑：
I should add, this is a timberframe, so one of the reasons I'm inquiring about the use of a vapor retarder like Membrain is because its installation would likely give me some advantage to detailing the air sealing.
我认为包括膜是一个好主意。在墙壁的内侧，在XPS的内侧，在XPS上，以防情况并不清楚。
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