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我有一些客户要求我审查他们房屋的墙壁装配设计。我的计划是将9英寸双螺柱墙壁框架造成密集的包装纤维素隔热材料。他们想知道，在密集的包装纤维素隔热和外部床单上塑造一个2×6的墙壁，构架单个2×6墙是否会更便宜或更有意义。有什么想法吗…。我将补充说，他们的担忧是价值，能源效率，成本和碳足迹。对于双螺柱墙，我的透视镜头值在R-33时，对于单个2×6壁，我的透视值是R-25，猜测泡沫并不能完全消除螺柱的热桥接。
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我要问的一个问题是，为什么9“而不是12”？似乎有很多人为此射击和R-40价值。另一个是，如果您在外面使用1英寸的泡沫，就足够了吗？我不知道您在什么气候。
My preference, rational or not, is to not use the foam, so I would be going with the double stud wall and cellulose. The thermal bridging becomes a non-factor, the assembly is permeable both ways, you can use organic materials and skip all the pesky foam chemistry questions, frame with 2x4 instead of 2x6 (lighter/faster although yes there are twice as many sticks), eliminate any issues of siding/trim fastening and window depth, and avoid showing your clients a dumpster full of foam cutouts headed to the landfill.
In remodel situations, with walls in place, foam outsulation makes sense. In new construction, you can get around it easily.
I think that question is best answered with a specific climate in mind. In addition, I suggest a review of the location of the air-tightness layer and the vapor retarder since they play as important a role as the insulation. So, in what climate zone is the project located?
Thanks David, the 12" was my plan but the clients wanted to lose less floor space. Another builder told them that the latter method would save a lot of time and money, but I don't necessarily agree. I would love to hear more thoughts........
抱歉，该项目在第7区。
[以后编辑：对不起；该项目位于4C区。]
对于一个不熟悉双墙框架的人来说，（当然）做单墙会更快一些，但是我敢打赌，这并不是那么快，“很多时间和金钱”对我来说似乎并不准确。我想知道丹·科尔伯特（Dan Kolbert）或其他做过的人是否会响起。显然，前期强调节省大量时间和金钱通常会导致他们余生中质量较低的产品。
Are you going to be submitting a firm price for your proposal, vs. a firm price from the other guy? Or, is this a situation where it's T&M and the guy who says "save a lot of time and money" enough times gets the job... whether or not it's true?
谢谢大卫。另一个建筑商刚刚被聘为顾问，以减轻客户的想法，我实际上使用了最好的方法来使他们获得美元的最佳效率。我对此没有任何竞争，但是我确实必须锁定该号码。我个人已经计算出隔热成本，并计算泡沫的成本，6英寸的墙的成本更高400美元。此外，安装床单还有一些劳动力，以及蒸气和壁板应用程序可能会导致的并发症防水。FSC2x4是.33/lf而不是2x6，即0.52/lf。考虑到2x4的木材，这似乎是400美元，这似乎是洗涤液。让我们不要忘记劳动和泡沫安装的麻烦。
Does anyone think I am missing something?
马太福音,
我会回应David的建议，并提出双框架并将厚度提高到〜12“。框架的成本大致相同，纤维素便宜，R值远远超过了1英寸的泡沫方案。您可以出售潜力，以相对于能源成本获得更好的热舒适度或更低的能源成本，尤其是在像区域7一样寒冷的气候下。
实际上，您的气候似乎太冷了，无法停在1英寸的泡沫。计算刚性泡沫护套的最小厚度
I don't think you're missing anything, but I would revisit the foam thickness and revise the cost and R-value numbers, along with the possibly greater difficulty of installing thicker foam and dealing with window depth and siding/trim attachment through thicker foam (i.e. you might be able to use nails straight thru 1" foam, but with 2" or more you are using screws or even adding battens).
As David guessed, I vote for double wall. It's pretty quick and easy building the second wall, you can use 2x4's for the exterior wall, and you avoid the use of all that foam. We've found exterior foam to be tricky to detail, time consuming, and you still need to figure out how to attach your siding.
You do need to figure out how to deal with bridging at your rim, rafter overhangs, and your ridge, esp. if it's a structural ridge. But I really see less and less reason to use foam above grade in new construction.
I just had the same configurations among those I priced out with the builder I want to use, Matthew. An interesting difference: the double-stud/cellulose package comes out to about 10% additional by his figures. He also suggested I switch the exterior insulation for Dow's SIS.
另一个区别：我们的气候是如此之多，就像其他人一样，我想知道那里是否有足够的热屏障。
I hope you'll let us know what they/you finally decide.
乔
我会让您知道他们的决定。谢谢大家的聊天，并将继续在这里寻找更多评论。
我知道我的立场。
还好I screwed up the Zone calculation, the project is in Zone 4C/ on the edge of the Marine/ Dry line. With this info any other thoughts?
The owners need to factor in the loss square footage with the 9" and 12" options.
On a basic 1,000 sq ft book they will lose 6% of their area with the 12" wall.
Most buildings are measured for permit, tax value etc by the outside of frame method so they will be paying 6% more for the part of permit based on sq ft and the portion of property tax based on sq ft.
If you ask me Richard, we have to make choices: A little square footage, or a lot of Energy Savings?
Matt, not a choice between Size and energy savings. Where you put insulation can affect both permit costs and property taxes. Locally both permits and to a certain extent, property taxes are based on size. Both measure outside of framing dimensions. So exterior foam is not within the "taxable" square footage, but thick walls are.
我在哪里，他们还算在外面的门廊和露台，我认为这不是一个强烈的论据。您要么想在任何地方便宜，要么想建造很多绝缘材料。当他们带着薄的高R值绝缘材料出来时，我们会说话，直到那时，越来越厚。