西雅图绝缘改造
Location: Seattle, WA, Marine Zone 4C
Type of Construction: Wood frame single family residence
Year Built: 1947
Size: 690 sq ft main floor, 380 sq ft basement
几年前，我购买了一所房屋，该房屋以前曾是30多年的出租房屋，并且自建造以来由同一家庭拥有。它的更改和更新方式很少。这是好是坏。无需撤消糟糕的做工，但几乎所有需要升级。也许是空白的？
这篇文章是关于绝缘。有一个从小型l amount of loose rock wool in the attic, none in the floor or walls. I am seeking feedback on my idea to create a conditioned attic, insulated walls and unvented crawlspace.
绝缘目标
Roof: R-58 (6″ polyiso above framing, R19 batt inside framing)
墙壁：R-21.75（护套上的1.5英寸Polyiso，在纤维素中吹R12）
Crawlspace/Basement: R 16.25 (2.5″ polyiso)
I am concerned about putting additional weight on the roof framing (2×4). I will consult a structural engineer, but wanted to float my ideas here first to make sure I am on the right track. Anyone have experience with 2×4 rafters?
I am occupying the home so projects will be competed in phases as budget and time allow. I want to get the details fleshed out before I begin. I have attached a few files showing the existing floor plans, sections and a wall detail with the proposed insulation.
I have learned a tremendous amount from this community and look forward to any insights and recommendations you all might have. Thanks!
GBA细节库
A collection of one thousand construction details organized by climate and house part
Replies
JD，
我认为您通过与工程师进行咨询，在正确的道路上。他或她实际上可以参观您的家并检查屋顶组件。也许您可以为现有的2x4姐妹姐妹一个更加强大的after脚，或者可以完全重建屋顶更有意义。
On the rockwool, take care that it is not contaminated with asbestos. See this article for more information:https://inspectapedia.com/insulation/Mineral-Wool-Asbestos.php
注意：以U因子为基础，屋顶甲板上方的R6.5/英寸Polyiso的6英寸，即使没有R19绒毛，也已经达到了IRC 2015代码。可能不需要增加2x4的深度，但可能需要项圈绑带。如果2x4是道格拉斯fir（可能是位置＆老式），而在中心而不是24”，则可能不需要项圈领带。
Consult with the engineer.
R19s are the crummiest straw-man excuse for insulation to come down the pike since R11s. If you're installing insulation under the roof deck, high density R15s between the 2x4 rafters would be a better choice. HD15 fiberglass or R15 rock wool is sufficiently high density to not lose performance to convection currents, even without an interior side air barrier. If you bump the depths to 5.5", go with R23 rock wool or R21 fiberglass, not R19s or low density R22s.
使用商业建筑拆除和重新屋顶的再生屋顶泡沫比Virgin Polyiso（65-75％的折扣！）便宜得多，但应降至R5.7/英寸以供申请，堆栈和气候。在6英寸的情况下，您将达到R34（接近代码敏的性能比您在U因子的基础上想象的（以及在R15中，您在R49 Center-Caventy中的R15，但性能要高于代码，由于R34并未被after子桥接。
您的附近（肯特）有一个泡沫收回者，价格合理的商品良好至良好的形状：
https://seattle.craigslist.org/search/sss?query=rigid+insulation
https://seattle.craigslist.org/see/mat/d/3-18-rigid-foam-insulation/63666789037.html
^^^ $ 22/表3“ Polyiso在范围内”。在我的附近，它通常在$ 15-25/床单上。它也可用于隔离地下室。
Steve, thanks for the words of caution. Residential rock wool is generally not known to contain asbestos-I will have it tested before beginning work. Thanks!
Dana, Pro tip on the reclaimed insulation in Kent-will definitely be in contact with them.
What do you think about forgoing the insulation under the roof deck and adding another 3" layer above the deck? 9" at R5.7 = R51. Cost wise is a wash (or cheaper) and would be much easier to install on the outside as some of the interior areas are very tight to get into. Thanks!
The awkward length & expense of the 10.5-11" pancake head timber screws for mounting 9" of foam with 3/4" nailer deck on a pitched roof gets a bit out of hand, and the aesthetics of a 10" fascia board can look a bit odd. At 6" of foam you're only looking at 7.5-8" screws, which is do-able.
仅6.5英寸R5.7/英寸的泡沫可保证您将以U因子的基础达到代码最小值，无论您在after子上有什么框架分数。
达娜（Dana），我附上了修订的图纸。只想确保我正确理解您。6.5“甲板下的甲板上隔热材料上方的polyiso。感谢您的帮助和快速回复。
It's better (= more air tight) if you use the self adhered membrane over the plywood you're adding to the skip sheathing. It's fine to use #30 felt under the shingles above.
The skip sheathing can sometimes be the achilles heel for air leakage at the rake of the roof, even with well sealed plywood over it. If there's enough room to work with to apply a shot of 2-3" of open cell foam on the underside to seal it all up it may be "worth it", adding a bit of R. As long as you're not putting fiber insulation in the rafter bays that decision can wait until you've proven how leaky it is or isn't with a blower door. You can also just chase the leak points with a FrothPak kit or similar, rather than foaming the whole shebang.
BTW: Most dry blown cellulose runs R3.7/inch these days, some dense pack runs R3.9/inch. So a milled 2x4 cavity would be more like R13-R13.7 rather than R12, not that it makes much difference in the "whole wall R".
代码最大U-FACTOR是U0.026，即（1/U =）R38.5“整个组件”。带有6.5英寸的R5.7/英寸Polyiso（典型的每英寸额定值用于堆栈中的商业屋顶，Polyiso是唯一的绝缘材料），您拥有Polyiso的R37，每半英寸都可以添加〜r0.5胶合板将其提高到R38。组合的内部和外部空气膜以及另一个R0.5左右的R0.8，用于木瓦上的上篮。（=
Your foundation detail shows a step-out /shelf before it drops to slab level. It's still worth insulating over that shelf and down to slab level (or an inch orr so above the slabe) with R15. Just be sure the cut edges of the polyiso don't rest directly on concrete- some sort of capillary break is necessary. (EPDM flashing tape over the cut edges would surely do it.)
Thank you Dana. This is fantastic information. I've got an inquiry in with my structural engineer and we'll go from there.