Mainstream construction air-sealing
It’s pretty well established that alternate air-sealing and vapour diffusion strategies are preferable to interior poly. Here in Canada, except in high performance houses, the transition hasn’t been made, but I understand in most regions of the US poly is no longer used by mainstream builders. When they stopped using poly, did they adopt alternative strategies, or simply stop using the poly?
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答复
Malcolm,
您可以加载您使用术语“替代战略”。该术语意味着（a）在过去，向外蒸汽扩散是一个问题，并且（b）如果构建器不使用内部蒸汽屏障来解决向外扩散，则需要另一策略来限制向外蒸汽扩散。
In fact, outward vapor diffusion is almost never a problem. In the case of wet walls, the two most common causes are (a) Bad flashing details that allow the penetration of wind-driven rain, and (b) Air leaks that allow warm, moist interior air to enter walls and contact a cold surface.
Your question implies an unstated question: Are most U.S. builders doing a good job of wall design and construction? The answer to that is no. The two biggest flaws I see are bad details for managing wind-driven rain and too much air leakage.
马丁，
我的帖子来自这里的另一个问题关于湿地下室OSB，在这里移动它来避免泥泞的讨论，我觉得我也搬了泥浆，我真的只对空气密封感兴趣。
The poster has batt insulated stud cavities and is worried about the moisture they contain, as drywall is about to be installed. But what struck me is that there doesn't appear to be any intermediate stage of air-sealing. No gaskets or caulking being talked about. So I wondered whether the most common air-sealing strategy in mainstream building is really just relying on a standard drywall installation, or whether anything more is done?
Malcolm,
The short answer: Every researcher who has looked into the matter has found that new homes in the U.S. are gradually getting tighter. I don't have these studies at my fingertips, but if needed I can look them up.
美国建筑商仍然有很长的方式去。如上所述a news story on GBA，2009年IECC设置了一个非常低的酒吧 - 只有7个ACH50。最近的一项调查发现，新的家庭建造者的“高百分比”是让吹风机门的门口在4到6℃的50之间。没有什么可以写回家的，但超过十年前更好地写作。（相信它）。
The most confusing thing about your question is the idea that when you include interior polyethylene, you have addressed air leaks -- and when you don't include interior polyethylene, you have a leaky house. Neither of these assumptions is true.
My state adheres to 2009 IECC. WRB is tapped and copious amounts of caulking/sealing is applied to the framing areas which are responsible for air leakage.
马丁，
The practice here in BC is to use the poly as an integral part of the air sealing strategy. It is continuous over the ceiling and walls, is caulked to the subfloor, window and door openings and all penetrations. The advantages are that it is inspect-able and yields fairly predictable results even without a blower door test. The disadvantages are that you have the poly.
So at present we have this detailed layer of air-sealing, and on top of that the drywall. What I wondered was: as builders in the US did away with the poly, did they continue any of the attendant air-sealing, or do you just end up with the standard drywall layer we have and an overlay? Maybe my assumption that poly used to be installed in the US with the same level of air-sealing is wrong?
I don't want to beat this to death, I'm just trying to understand how drywall, installed without other air-sealing strategies doesn't lead to problems, or if other air sealing is done, what trades are doing it when?
Malcolm,
当内部聚乙烯在佛蒙特使用时，没有人披露任何东西 - 很少有建筑物已经听说过气密电动盒子。所以聚乙烯并没有真正有助于气密性。当佛蒙特州建造者使用poly时，他们的房屋泄漏了。当他们停止使用Poly时，他们的房屋仍然泄漏。
The fact that you are caulking seams and caulking the poly to the subfloor and penetrations obviously makes a difference. If builders in BC wanted to use this approach when installing drywall instead of when installing polyethylene, the effects would probably be similar.
In other words, the key is the caulk.
Malcolm,
如果您正在寻求更好的替代方案，而不是多于空气密封墙......
我会考虑胶合墙壁护套，胶带，仔细密封泥浆门槛，窗户和其他渗透（胶带，垫圈，填缝）。或气密干墙接近，密封盒和干墙/地板交叉点，以及阁楼的墙壁顶部。还有空气密封产品，允许水蒸气透射（比智能蒸汽屏障更昂贵）。
今天美国建设者在做什么，这在过去有点改善？正如马丁所说，一般而言，他们可能没有做得多。但也许更小心地使用Tyvek或类似的散装水和允许蒸汽透射的空气屏障，施加在壁套上。我们可能没有良好的数据，以近似于对美国各种气候的新建进行的空气密封实践的百分比。
The problem with poly for air sealing is that it traps moisture in walls. And as Martin notes, installing poly is usually not stopping air leakage around windows/doors/electrical boxes/mudsills, or tops of walls in attics. That pretty much describes what I did 30 years ago.