Insulation approach for an above ground sandstone wall
I am renovating a 1905 wood frame house in Pittsburgh, we have cold winters and hot summers. The basement for the house is sandstone and is above ground. Only the basement floor is below grade. The basement walls are probably 2′ thick. I want to insulate the basement, it will be heated as it will be living space. But I want to take advantage of the thermal mass of the walls so my thought is to add 2″ external rigid foam with some kind of siding on top of to keep water out. I’m wondering if anyone has experience with this approach, or a better idea? It’s weird not having an underground foundation.
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答复
Hi Beth,
您是否阅读了马丁关于绝缘地下室的文章？看//m.etiketa4.com/article/how-to-insulate-a-basement-wall。
这是我的外行根据阅读各种GBA文章的看法。（也许专家承包商会在随后的帖子中发声。）
您的石墙是用统一切块制成的吗？如果是这样，在内部将回收的刚性泡沫应用到内部可能会容易得多。如果表面不均匀（更像是瓦砾墙），则GBS文章通常建议将闭孔喷雾泡沫安装到内壁表面上。
我想知道的一件事是，石材的水分储层性质是否引发了任何其他问题。
嗨，史蒂夫 - 谢谢。我已经读过马丁的文章，大概几次。但是我尚未确信，值得通过在内部绝缘而失去墙壁的热量。石墙绝对不统一，我希望很难挂在上面。我可能会看到创建一个外墙，然后用喷雾泡沫填补它与石墙之间的间隙。而且我知道从木材框架到外部石材上发生的任何事情的过渡将是关键。
Hi Beth,
GBA上有有关热质量的文章：//m.etiketa4.com/article/all-about-thermal-mass
本文指出了以下关于热质量在较冷气候下如何工作的信息：
"If daytime highs are 50°F or less for months at a time — as they are in colder areas of the U.S. during the winter — thermal mass won’t help much. After all, heat is flowing through your walls in just one direction: from the interior to the exterior. Under these condition of steady-state heat flow, you need insulation more than you need thermal mass."
好文章,谢谢。我的观点是that the mass already exists, and insulation can be added. It's not a question of one or the other. And the space within will be heated and cooled as part of the central heating/AC system. I believe the R value of the thermal mass is insignificant in this case. I believe (hope?) the effect of adding insulation "should" stop heat and cold flowing through the massive wall. It's just a matter of does the insulation help more on the inside or the outside of the mass wall. If it's on the outside, there will be a lag time between getting heat stored into the stone, or, getting the stone cooled during the summer, but I think the dissipation rate is very much slowed because of the insulation. Or conversely, if the insulation is on the inside, won't it be fighting the exterior temperatures stored within the stone walls? I also haven't gotten to thinking through any condensation problems. But I'd rather have that be outside between the stone and the insulation then inside behind the insulation.
另外，有：//m.etiketa4.com/article/exterior-insulation-for-an-ugly-brick-building。我认为这类似于我要做的事情，但正在寻找一些输入。
Hi Beth,
This site (https://www.naturalstoneinstitute.org/designprofessionals/technical-bulletins/rvalue/) indicates that the R-value of limestone is between .067 and .114 per inch. If this is accurate, a 24 inch thick wall would be between R-1.61 and R-2.74.
Martin's article suggests it makes more sense in a heat-dominated climate to put the insulation on the inside.
Of course, you may be right that the limestone is analogous to the brick in the "Ugly Brick" article. (Advice on insulating brick walls often includes a lot of "it depends" statements.) I would note that the contractor was installing rigid insulation continuously from the footer all the way to the roof line (along with putting in new windows and bucks).
Maybe we can get some input from someone who works in your region.