Interior Insulation Retrofit of Masonry Walls
I am working with a contractor to buy a ~1900 stone house in the Philadelphia area. Currently the house has been reduced to bare walls and flooring. The architect has called for a simple 2×4 stud with fibreglass batt insulation with a 2″ air gap. I am concerned that despite stuffing the studs with R20, the effective R will be considerably lower due to the thermal break of the wood stud and lack of Air Barrier. The architect has also not suggested any insulation in the basement floor, which is to be 1/2 completed.
我曾在英国历史悠久的砌体博客中读到，应使用可渗透的岩壁舒适板80连续绝缘系统维护和考虑气隙。我必须扭转系统，我考虑了：
2×2 furring strips (providing 1.5″ air gap)
Comfortboard 80
Plywood
aw/wrb
2×4 studs with Comfortbatt
I am now however reading from Building Science that masonry walls should in fact be sealed from the inside with closed-cell foam if possible to stop freeze-thaw inside the gap when the temperature significantly drops from the inside insulation. The temperature does get down to 10F around this time of year so I can see a situation where the temperature differential inside the house will be significant. I had thought that using a permeable Rockwool would enable vapour transmission for drying, but had not considered the temperature issue.
Any thoughts are warmly welcomed because Building Science often discusses only brick, and I am unclear if a 16″ stone wall would be a similar proposition.
Thank you
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
答复
SPF Over Stone Foundation是必经之路。
It is hard to air seal a lumpy surface any other way. With an insulated assembly the stone will be very cold, in cold climate interior air leaks can condense on the stone and can create mold issues. Having an assembly that is vapor open, such as mineral wool, will only make this even worse by also allowing interior moisture to diffuse.
我周围有很多旧房屋，有2'+的石头粉底（气候区5），它们仅被玻璃纤维棒隔热。它主要有效，但后面总是有一些霉菌问题。
Provided you deal with exterior water leaks, with SPF you won't have issues. Once the SPF is up and seals the foundation, you can fill the rest of the stud cavity with batt insulation. Important item is not to install a vapor barrier anywhere in the assembly.
Thanks Akos. By SPF, I'm assuming you mean Spray Foam? I think Building Science recommend a Closed-Cell foam. I'm not entirely clear why that would be better than Open-Cell and the differences, but is that what you're suggesting with metal or wood studs?
Yup spray foam. Closed cell spf foam works well in this application as it is also a vapor retarder which is what you want. I would follow the BSC guidelines:
https://www.buildingscience.com/documents/insights/bsi-041-rubble-foundations
I never understood the thinking behind metal studs in a basement. I guess maybe if you are very tight on space a thin 1 5/8" steel wall makes sense. If the conditions are bad enough to cause issues with wood studs you have much bigger problems than the construction of your walls.
Metal studs are also a pretty big thermal bridge, you loose about half the R value of the insulation you put between them. I would only use metal studs if required by code.
向内部喷涂泡沫似乎确实是一个常见的答案。我唯一关心的是，这会改变蒸气曲线，然后石头和关节只能干燥到外部。有趣的是，以下链接与砖头讨论了这一点：
https://www.proremodeler.com/insulating-old-masonry-buildings
他建议使用气隙和水排水管，然后再隔热材料……建议似乎与大多数人所说的不使用蒸气屏障相抵触。闭孔泡沫不会是那种蒸气屏障吗？绝对是一个艰难的选择
您可以尝试使用Dimple Mat提供排水层，但是很难在不平坦的切石粉底上正确安装。
我同意阿科斯（Akos）的观点，即闭孔喷雾泡沫是这里要去的方式 - 砖石墙和未通风的大教堂天花板是两种大型利基应用，喷雾泡沫确实是最好的选择。在足够厚的层中，闭孔喷雾泡沫是一种蒸气屏障，但这不是砌体的问题，因为砌体并不真正在乎它是否湿，因此不需要干燥。如果您有大量的水问题（从墙上流出了水），那么这是通过分级，排水沟以及可能的砾石和法国排水口在外部最好解决的问题。
Bill