Insulating Stem Wall / Floor of Encapsulated Crawlspace
Insulating my crawlspace is something that will happen soon-ish. I’m located in climate zone 3C (coastal California) and have already encapsulated the crawlspace with good results. Still – no insulation yet.
The ground ouside the home is basically level with bottom of the rim joist (sits a few inches below it). See attached quick sketchup drawing.
It makes obvious sense to insulate the rim joist. The normal advice is to then also insulate the stem walls…but not the floor. Why?
I’m sure the ground temperature near the surface is colder than a few feet down but given the total square footage of stem wall to dirt floor, I can’t make much sense of this from a BTU calc.
I’ve tried my hand at even modeling this in THERM for guidance but ground contact assemblies seem to be something of a dark art.
My intuition tells me that insulating the stem wall and not the floor is akin to something like really good insulation with single pane windows. The heat is just going to bypass around the stem wall.
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