Vaulted / cathedral ceiling insulation
Ok, I’ve been reading on here and FHB for days about insulation. Here’s my situation:
Home (kitchen) remodel:
一段时间前，我的鳕鱼风格的马里兰州家园的后面放了一个小门廊。大约25’x6’。棚屋顶3/12沥青和2×4 afters。最终，它后来被关闭，成为厨房风格的厨房。
When the porch was closed in, a poor flashing/ water management job led to severely rotted walls.
I bought the house 6 months ago with intentions of installing a rear deck. After lifting the siding and discovering the damage (a not so pleasant conversation was had with my 900$ home inspector.)
After weighing my options, let the kitchen remodel ensue.
Trying to save money and time here’s what I decided:
-Rear exterior wall and 6′ of each side wall completely replaced.
- 新的墙壁用常规的2×4框架和拉链系统护套建造。
-Re-attached roof to new exterior walls.
-Wife decided that the slanted ceiling looks “Nice” as opposed to a flat ceiling.
- 花几个小时研究隔热实践使我在这里。
屋顶有一个通风的拱腹，可循环到膝盖墙后面的阁楼空间。通过在侧壁上高的通风口进行通风孔（我不太确定这种做法，但这是一个不同的问题。）
我知道我需要在1英寸的空间。我喜欢使用1英寸刚性泡沫（建造的站点）挡板使空气流通的想法。我已经阅读了Mike Gurertin的文章，他在其中使用了箔纸面对的刚性泡沫，但此处的大多数文章建议使用Owings Corning XPS。为什么在实践上有所不同？
After I figure out what type of foam to use my main question is what the heck to put below that?
对我来说，最具成本效益的是玻璃纤维。
面对/不面对面？我需要蒸气屏障还是延迟器？
我能说的是最好的做法是使用空气密封的干墙和蒸汽阻燃油漆的未面面板？
我还想在天花板上涂上油漆的T＆G松树。
Any guidance with this mess of information would be greatly appreciated.
Thank you
安迪
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Replies
安迪,
You are mistaken when you write that "most articles on here recommend using Owings Corning XPS." In fact, green builders try to avoid the use of XPS (since XPS is manufactured with a blowing agent that has a high global warming potential).
Your biggest challenge is the fact that the rafters (2x4s) aren't deep enough to allow you to install enough insulation to meet minimum code requirements.
If you read these two articles, all of your questions will be answered:
How to Build an Insulated Cathedral Ceiling
Site-Built Ventilation Baffles for Roofs
I might be guilty of writing comments that could be interpreted as recommending Owens Corning XPS. For the record, I do not recommend Owens Corning XPS. It's not quite as terrible as Dow XPS, but it's plenty terrible and about a hundred times worse than foil-faced polyiso.
安迪,
我关于现场通风障碍的文章继续解释了为什么，即使有些人坚持安装蒸汽渗透通风挡板，我也不认为挡板的蒸气渗透性很重要。
您写道：“我对面对的箔纸的关注是，它会通过成为另一个蒸气屏障来捕获空气中的空气。”这句话混淆了两个概念。解开它们：捕获空气很好。（您总是想争取气密性。）在某些组件中，捕获蒸气可能是一个问题 - 但是在通风障碍的情况下，即使使用蒸气易变的材料来使该水分问题也没有任何报道通风挡板。
In Maryland (Climate Zone 4), the 2012 IECC mandates that roofs should have a minimum R-value of R-49, not R-24. So if at all possible, R-49 (or better) should be your target.
Thank you both for the info!
Martin,
谢谢你的快速反应！我很抱歉，我忽略了我用2x8的2x4 r子姐妹，这样我至少可以在那里获得R19 batts以及泡沫，这将使我的价值为R-24。
Home Depot的Polyiso Foil面对的板是6点时更高的R值，这是我最初想要使用的。
My concern with the foil faced was that it would trap air in the cavity by being another vapor barrier.
I guess my confusion with the XPS comes from one of the articles you provided where it says..
“（如果您使用刚性泡沫作为挡板，选择薄EPS或XPS而不是箔面对的多氰透明尿素可能会更有意义有点蒸发，而面对箔却是蒸气屏障。）
I'd like to be as energy conscious as possible without spending an arm and leg.
Martin,
感谢您为我打破这一点，您可以告诉我我对这个东西的新手。我将远离XPS，并坚持使用我的原始计划，以使用箔面泡沫。
至于实现R-49 ..这将是很艰难的，但是我将继续研究能够靠近的方法。
This website is such a great resource and i appreciate all knowledge and advise you guys share!