How do you do Larsen Trusses and cellulose on the outside of an old house?
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Can I add Larsen Trusses and cellulose to 1920s House in Minneapolis?
Ken Traefald
Feb. 17, 2020Last updated: Sept. 9, 2020
我在明尼阿波利斯有栋20世纪20年代的房子，我在考虑把墙板拆下来用密集的纤维素加12英寸深的拉尔森桁架。我在Fine homebuilding杂志中看到的指南建议，最好的路线是应用poly barrier在外面，因为从桁架中获得的r40将阻止任何水分凝结在poly上。我将使用1/2“胶合板的外壳和一个透气的房子包裹，然后一个雨幕和壁板。
When insulating the exterior of old homes to improve energy-efficiency you need to be careful not to trap moisture inside walls. What you read about installing a poly vapor barrier on the outside of a building is not a wise. I’m wondering if perhaps you misread that? You should never put a vapor barrier on the exterior of a wall in a cold climate, which Minnesota most certainly is.
An R40 wall of EPS foam would in itself act as a vapor barrier and react as you suggest, but with dense packed cellulose insulation, moisture would migrate thought the wall in winter, be unable to leave due to the poly, and it would rot. Here is a page on exterior house insulation that will explain, including how Larsen trusses and cellulose were used on a Passive House.
How to insulate the exterior walls of old homes and not trap moisture inside
In your question you imply two different wall assemblies, so help me out to make sure I understand – the poly on the outside is not a good idea, but your other suggestion makes more sense providing you assemble it in the correct order. If you strip the walls, install a plywood sheathing, tape the joints as an air barrier, theninstall Larsen trusses, cellulose and a breathable house wrap membraneyou would be far better off than the idea of an exterior vapor barrier.
就我个人而言，我不会对粘合在护套上有任何问题，因为这样你的蒸汽屏障就会很好地位于墙的三分之二附近，蒸汽屏障外面有三分之二的绝缘材料。这些都说得通吗?如果我有什么误解，请随时询问后续。Here is another page would help explain, ourbuilding science made easy video, which explains the how vapor moves through walls, and how to properly manage it.
也许我的措辞应该是，把聚物包裹在护套上，然后钉在拉森桁架上。我的房子和大多数20世纪初建造的房子一样，内部有灰泥和带油漆的板条，有2x4的螺柱，用吹入的纤维素隔热。外护套板为1 × 8的。我对墙壁做了热扫描。似乎没有任何多余的纤维素沉淀。冬天的时候我检查过阁楼，没有多余的湿气。你说，把墙拆了，装上胶合板。你的意思是要剥掉1x8的护套板吗?如果是这样，是否可以将胶合板钉在现有的护套上?那时你可以用胶带把胶合板连接起来。 Then you could seal the edges of the poly to the plates and install the Larsen trusses.
I'm still looking at the Rockwool Comfort Board 80 option too. Would it work to use a self adhering WBR, on the sheathing and then insulate with 8" of Rockwool or is there to much potential of condensation in the Rockwool in a house like mine.
我发现Delta Vent SA的网上价格是每561平方英尺569美元。卷。这是典型的价格吗?备选方案:Henry Blueskin VP-100 WRB每400平方英尺239美元。Ft和有33的烫发等级;而Grace Vycor en V-S WRB是每480平方300美元。ft and has a perm rating of 15.
我可以特别订购2英寸厚度的岩棉舒适板。如果我这样做，我想放两张纸，然后是水平的钉子，然后再放两张。如果我选择在外面隔离地下室，你会把墙板放在外面地下室板的金属装饰上面，还是留下一个小间隙?当处理床单时，你通常使用什么尺寸，48x96或更小的?一个人递上一张2英寸的全尺寸纸是否可行?我的装置就像你在视频里做的一样。
Seperate question. Have you used the LiteZone windows in any of you Eco homes?
Hi Ken,
I pasted your questions and points here, my responses are in bold -
你说，把墙拆了，装上胶合板。你的意思是要剥掉1x8的护套板吗?
关于拆板的事，抱歉，没有。我更多的是在询问而不是建议。如果你有一个带有1x8s的框架墙，它是固体和方形的，满足代码和雪负荷的要求，那么我自己会保留它们。
I'm still looking at the Rockwool Comfort Board 80 option too. Would it work to use a self adhering WBR, on the sheathing and then insulate with 8" of Rockwool or is there to much potential of condensation in the Rockwool in a house like mine.
你提到你是在模仿我们用8英寸厚的外部岩棉做的墙壁组装，这个组装效果很好。水分通过岩棉没有问题。
我发现Delta Vent SA的网上价格是每561平方英尺569美元。卷。这是典型的价格吗?备选方案:Henry Blueskin VP-100 WRB每400平方英尺239美元。Ft和有33的烫发等级;而Grace Vycor en V-S WRB是每480平方300美元。ft and has a perm rating of 15.
In a cold climate you can install a vapor barrier at the 2/3rds point (with 2/3rds of insulation on the exterior), so depending on the thickness of the wall, the perm rating may not be that important, we had a 2x6 wall at 5.5 inches thick so it wasn’t perfectly at the 2/3rds point but with 2x4s I think you are.
我可以特别订购2英寸厚度的岩棉舒适板。如果我这样做，我想放两张纸，然后是水平的钉子，再放两张纸。如果我选择在外面隔离地下室，你会把墙板放在外面地下室板的金属装饰上面，还是留下一个小间隙?当处理床单时，你通常使用什么尺寸，48x96或更小的?一个人递上一张2英寸的全尺寸纸是否可行?我的装置就像你在视频里做的一样。
Rockwool doesn’t come in 4x8 sheets that I know of, so smaller ones I bet you can handle yourself, but I really can’t weigh in on whether or not this is a one or two person job.
We rested our exterior insulation panels on the exterior insulation of the slab. Metal is a conductor, so keep that in mind. Not sure what you mean by ‘leave a gap’, any gaps in insulation should be filled.
We did it with strapping for ease and we thought to save a bit of money on materials, and it worked fine, but it was pretty labor intensive. It may cost about the same to go with something like Cascadia Clips to install the insulation without thermal bridging as well.
Seperate question. Have you used the LiteZone windows in any of you Eco homes?
We have not, and I couldn’t confirm the R19 value they put on them but they do work very well by creating multiple sealed air chambers while keeping the window lighter than had you installed triple pane glazing.