8″ of exterior mineral wool (Comfortboard 80)
I am in zone 7 (Northern Minnesota). Looking at building timber frame structure without SIPs. I love the idea of using Roxul Comfortboard 80 for exterior insulation. I want to avoid foam as much as reasonably possible even though I will most likely need to use it for the roof. Wall assembly would be 2x4s sistered onto outside of timber frame, exterior plywood, WRB (Delta Vent SA), 8″ of Roxul Comfortboard 80, vertical furring strips and then siding.
我没有看到任何在外墙上使用8英寸矿物羊毛的例子。这将是3“和2的2层”。8“会给我大约r34。在2x4之间添加矿物羊毛将至少给予R 40。不列颠哥伦比亚省温哥华市有一个很好的文件http://www.victoria.ca/assets/Departments/Planning~Development/Permits~Inspections/Example~Plans/Illustrated-Guide-R22-Effective-Walls-In-Wood-Frame-Construction.pdfthat details how to attach 8″ of exterior mineral wool.
Besides worrying about hitting a stud through the furring strips, is there any reason why this wall would not be feasible or performant? Anyone used 8″ of Comfortboard 80 on exterior?
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大卫，
Roxul has published a design guide with advice on continuous exterior mineral wool panels up to 12 inches thick (see table reproduced below).
Here is a link to the design guide:Residential Insulated Sheathing – Design Guide.
For more information, contact a technical help representative at Roxul. (The company now has a new name: Rockwool.)
For information on a project that included 6 inches of exterior mineral wool, seeWrapping an Older House with Rock Wool Insulation.
马丁，
Thank you for that link! I find it somewhat difficult searching on their website.
Edit: After reviewing that doc I see they then reference another doc for fastening that I had to google:https://static.rockwool.com/globalassets/rockwool-na/downloads/technical-guides/residential/fasteners_guide_techguide_en.pdf.
Found another excellent reference from the 15th Canadian Conference on Building Science and Technology in a paper titled "STRUCTURAL TESTING OF SCREWS THROUGH THICK EXTERIOR INSULATION"https://buildingsciencelabs.com/wp-content/uploads/2017/11/CCBST-2017-Structural-Testing-Screws-through-Thick-Exterior-Insulation.pdf.
该研究的主要目的是评估长螺杆通过绝缘的垂直载荷电阻作为具有特定聚焦在相对厚的矿棉的相对厚的绝缘层（相当于柔软板80和110）上的覆层附着技术。
They found that with a typical cladding load of 25 lb per fastener the deflection was less then 0.025" which is likely insignificant considering a one story wood-frame structure is expected to potentially have moisture shrinkage of 3/8".
Some key findings I noticed:
- deflection difference between 6" of XPS and 6" of mineral wool was 0.005". Basically no difference.
- the difference in deflection between using 6" of mineral wool and 12" of mineral wool was 0.007"
- 当紧固件安装到3/4“胶合板护套中时，只有在螺柱框架中为紧固件安装了类似的载荷偏转响应。
这让我充满信心，即使是9“的舒适板80也不会是一个问题，特别是在使用HECO Topix螺丝时。
大卫，
Thanks for the second link.
Hello David, can you update on the installation of the ComfortBoard 80, please? I'm building a timberframe this summer in Northern Maine (climate zone 7). Planning to enclose the frame with 2x4 stud wall, sheathed, wrapped in air/water/vapor barrier, rigid insulation, rain screen, and cladding.
Successes? Failures? Tips? Which insulation did you use for the roof and under the foundation?