总结中的蒸气屏障
和祖父母d of mine today who is in the tail end of GC’ing a complete remodel of a 1920’s 2 story Victorian in Minneapolis ZONE 6b he mentioned that he was going to use a layer of poly in the 2nd story ceiling, drywall and finally blow the attic floor with cellulose. His main rational for doing so is because the BI called for a poly vapor barrier. I suggested he instead consider VB paint and that would effectively meet code and also avert many of the much publicized concerns over using poly specifically raised in the blog post from the other week. Although it was interesting to read Doug M persistent defense of the poly as he is from MN as well…………… my friends concern is whether the building inspector will allow for the VB paint. Understanding all building codes are different and untimely he wil need to get the final ok from the BI on whether he will also for the paint ……..I did have a few questions.
1）涂料是否需要成为VB Spec'd或2种胶乳的底漆足以满足？
2) He is using closed cell SPF in the walls, controlling interior humidity/vapor becomes extremely important as the house will be very tight. Thus the poly in the ceiling would seem to very much run the risk of condensation especially in lieu of them having AC during the summer. Right?
3使用Poly的垮台已被充分记录，但使用VB涂料确实有任何缺点缺点等。
Assuming the BI allows for the paint is their any good reason that poly would be preferable? His insulation contractor suggested in “remodels” paint is often ok’d, but in his case because the house is down to the studs, essentially its considered new construction and thus the BI will mostly likely want to see the poly? I see the rational on why the insulation contractor say it but again the logic seems to be lacking.
我想如果BI播放难以通过确定的麦白。有人用过它吗？
Replies
M.S.,
问：“涂料是否需要成为VB规格或任何基于乳胶的底漆足够的涂层？”
答：您必须检查当地的代码书，但许多代码呼叫液态延迟器，渗透不超过1次烫发 - 换句话说，蒸汽延迟引物。您需要一个已测试渗透率的油漆。
Q. "The poly in the ceiling would seem to very much run the risk of condensation especially in lieu of them having AC during the summer."
答：在夏季的空调房屋中，没有滤热的天花板比用聚合物保持干燥器。但是，我没有听说明尼苏达州天花板多的严重问题，所以我认为没有足够的凝结造成问题。
Q. "Does using VB paint have any disadvantages, shortcomings etc.?"
A. No.
问：“假设BI允许涂料，是它们的任何好理由，优选的是优选的？”
A. No.
Q. "The BI will mostly likely want to see the poly."
答：我没有看到任何理由（除了无知）为什么这会如此。我不认为国家中有任何住宅建筑码，需要在天花板中聚保。
Q. "I guess if the BI plays hardball, then MemBrain by Certainteed."
A. MemBrain would certainly work.
Martin, as I understand it, poly was installed to prevent vapor from entering sealed areas where potentially damaging condensation could take place (i.e. wall cavities). Assuming that an attic is properly ventilated, can you think of circumstances when a vapor barrier would be beneficial (for example extreme humidity levels such as swimming pools)? We see moisture issues in unconditioned attics all the time but they are due to missing air barriers and inadequate ventilation - not missing vapor barriers. Where we find poly installed over the ceiling drywall, mold issues are not uncommon especially when insulation levels are inadequate (Zone 5).
Torsten,
在冬季，蒸汽驱动通过冷酷气候天花板是从内部到外部的，所以蒸汽迟缓的涂料是有道理的。它将减缓内部水分的扩散，倾向于迁移到天花板组件中。
您声称模具与使用天花板蒸汽屏障有关。我令人怀疑的协会。我经常在浴室天花板上看到模具，特别是靠近外墙。发生这种情况，因为绝缘在墙上的顶板上非常薄，并且在冬天的干墙天花板上很冷。这就是为什么水分和模具积聚在那里。该溶液是绝缘体较厚的绝缘和凸起脚跟桁架。
If the attic is vented correctly, poly in the attic will work fine as long as the attic is also air sealed. We have used .Membrane for a while now and it works fine. Air sealing is as important as the insulation. Do not rely on any kind of paint for a vapor barrier.
Tim,
我对你的陈述感到困惑，“不要依赖任何类型的涂料来蒸汽屏障。”你是对的，油漆不是蒸汽屏障;这是一种蒸汽延迟器。但建筑规范不需要蒸汽屏障;他们只需要蒸汽延迟器。
蒸汽延迟器涂料可靠地进行，在石膏干墙上产生1倍烫矿表面。这就是建模代码所需的所有内容。