Attic insulation reality check
Nate g| Posted inEnergy Efficiency and Durabilityon
It’s time to get my attic air sealed and re-insulated and I’ve committed to hiring it out since the 6/12 pitch truss attic is a horrible place that I hate to work in. I’m having trouble finding people willing to blow cellulose. Everyone around here seems to want to blow fiberglass. Is this a major issue?
The first bid I’ve gotten is $3.20/sf for attic floor air sealing and R-30 worth of blown fiberglass. Sane/insane?
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Replies
Nathaniel,
我认为它是。当我第一次在这发生了浓厚的兴趣stuff a few years ago one of the first things I saw was a youtube video showing a demonstration of bulk water being poured on cellulose vs fiberglass. The cellulose shrunk drastically while the fiberglass just shed it with the water going to the bottom of the container. They then stated that fiberglass is material of choice. If you didn't know better and had an incurious mind one would actually believe the urban legend shown in that video.
Apparently in large parts of the country the insulation blowers also have incurious minds that will latch onto the easiest, laziest explanation for anything. When I tried to find cellulose blowers locally it was hard to find. They all wanted to blow fiberglass and when pressed for an explanation they said it would handle water better. Yeah, right.
What those youtube demonstrations were really showing is that if you have any bulk water intrusions, either through air paths or simple leaks, the first thing that will happen with fiberglass is water will reach sheathing and rot it. In contrast the cellulose will absorb it. The experiment in the video wasn't realistic at all though because the biggest problem isn't rapid bulk water intrusion that collapses the cellulose, but slow intrusion. In slow intrusion of water in cellulose the cellulose has the ability to spread the moisture to its neighbor and decrease the local density.
让我吸引的是，如此多的人以谋生为生的人是如此无知。这很令人失望。正如它所说的，人们看到了他们想看到的东西，而剩下的则无视。
对于我附近的玻璃纤维来说，价格为10美分/每R英尺安装的价格，但这还包括广泛的鼓风机通向空气密封，这可能不是问题。
从25年前开始的低密度玻璃纤维的冬季性能问题已大大解决 - 它比以前要好。目前尚不清楚他们是否解决了将削减为冷却季节表现的红外半透明问题。但是，即使这仍然是一个问题，在R30+的情况下，它不会像舒适和效率的灾难一样，它回到了1990年前的时代，当时R19是Code Min Min Attic绝缘，许多气候。
埃里克（Eric） - 没有火箭科学家（或建筑科学家）浪费他们的职业，即安装绝缘材料。但这没关系 - 我不愿为这项服务支付火箭科学率。无论是玻璃纤维，纤维素还是其他东西，是安装的质量使其造成或破坏它，而不是安装程序的知识深度。给我一个首先空气密封的人，以正确的平滑甚至深度安装隔热材料，没有缝隙，凹陷或空隙，不会阻塞阁楼通风口，并自行清理，即使我是一个快乐的人，即使安装人员陷入了高中数学的速度，并认为月球着陆并不是一个精心制作的骗局。有很多细节要正确，一个安装人员对其工艺感到自豪，比他们对不同绝缘材料的相对特性（或不知道）更为重要。
Dana, I agree that pride in workmanship is important, maybe most important. But you may be ignoring an important point. If a person just handles the basics by rote and never thinking much about it, then stuff happens. If something happens out of the ordinary to that individual, or the circumstances are slightly different from what he/she is used then that person will likely bungle it. That's because they are used to assessing things without analysis. Happens all the time. People like that are thrown for a loop easily. That's because people like that generally don't know what they don't know. It's the Dunning-Kruger effect.
To quote Wiki: "The Dunning–Kruger effect is a cognitive bias wherein unskilled individuals suffer from illusory superiority, mistakenly assessing their ability to be much higher."
Oh that reminds me... How important is it to also do the attic floor that's over an attached garage? The garage isn't used for anything other than typical garage stuff, but it does get scorchingly hot in summer and very cold in winter. And there's a water heater in there.
Eric,
达娜（Dana）有一个称呼它为“创造性的愚蠢”。达娜（Dana）在关于绝缘和空气密封的另一个问题上写道：“但是……您做出的事物越多，白痴变得越有创造力。”- 更多信息请访问：//m.etiketa4.com/community/forum/general-questions/36982/Insulation-VS-VS-Air-flow-extra-extra-extra-extense#sthash.ey77beryi.dpuf
Nathaniel,
The answer to your question depends on your climate. Most garages aren't insulated. But if your garage gets "very cold" in winter, I'm surprised that your water heater is located there. Obviously, you don't want your garage to freeze if there is plumbing there.
我猜想您的车库不会冻结，这就是为什么水管工将热水器放在那里的原因。我还猜想您住在“非常冷”的地方很温和。
内森（Nathan），我刚刚在我的添加阁楼上吹纤维素约20英寸（R60），每平方英尺约1美元。这不包括空气密封。
为了响应水分的想法，为什么您的阁楼上都有大量的水？而且，如果您确实有散装水，则无论您有玻璃纤维还是纤维素，都会遇到问题。问题不是此时的绝缘材料类型，可以确保您的屋顶不泄漏，通风正确。
决定以$ 2/平方英尺的价格出价，用于R-30玻璃纤维和两次鼓风机门测试（一个之前，一次），并带有鼓风机门定向的空气密封。我更喜欢纤维素，但价格是正确的，我厌倦了试图追逐任何可以做到这一点的人。即使我能高度怀疑，我也能找到任何可以得到没有硫酸铵的东西的人。
相关地，你们是否知道欧文斯·康宁（Owens Corning）是欧文斯·康宁（Owens Corning）绝缘的制造商，欧文斯·康宁（Owens Corning经过认证可以安装Owens Corning绝缘材料？这些家伙正在运行的会员计划...
I hate blown fibreglass. It seems to collapse like a souffle if you so much as look at it, and unlike cellulose it won't fluff back up to the depth it was previously. Also, lower R value per inch means that eaves will have even less insulation above the top plates (depending on construction). And wind washing is much more of an issue. I am loathe to disagree with D Dorsett on anything (extreme folly!) but in this case I think the product does matter, and it's not simply about quality of installation.
哦，我忘了提到纤维素的回收含量为85％，而记忆中的玻璃纤维（？）则为30％。我可能犯错，或者可能是特定品牌或过时的。在这些文章之一的某个地方捡起了它...
Newer fiberglass blowing wools aren't as easy to "fluff" to a low density/easy collapsing level as the stuff of 15+ years ago, but I suppose anything is possible if you have a dishonest contractor trying to skimp on material. Unlike the older stuff, some of the new open-blow wools (such as Owens Corning AttiCat) is bagged as granulated higher density kernels/beads of fiberglass that maintain much of that structure as it's blown, with virtually zero settling over time.
虽然(我个人不喜欢的东西足够了number of basis') that I would DIY cellulose with a rental blower rather than have a contractor blow fiberglass, it's not quite as lousy a product as it used to be. As long as the blower door testing verifies the air-tightness prior to blowing the fiberglass you'll avoid the issue with infiltration dragging airborne glass fibers into the conditioned space, a common disaster when blowing fiberglass into air-leaky assemblies.
It's not hard to find sulfate-free cellulose though- even some box stores would special order "stabilized formula" goods (designed for damp spraying, and almost always sulfate-free, and performs just as well when dry-blown), from their standard suppliers without a significant up-charge. But if you're not up for a DIY and there are no contractors handling cellulose in your area you're kind of stuck. In my area you almost have to seek out sulfated cellulose when buying through materials distributors catering to contractors, but the box-store retailers catering to DIYers seem to only stock sulfated goods.