Foam under slab? Zone 4B
jackofalltrades777
| Posted in Green Building Techniques on
Is it worth putting 3″ of rigid foam under a house slab (no basement-slab on grade) in a Zone 4B climate?
Some claim it’s not worth it as in the summer, it’s better to have the slab connected to the groun for the cooling effect. In the winter, the foam might help but it’s offset by the summer loss of using the ground to cool the slab.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Peter,
We are planning our future home build in CZ 4B (southwest New Mexico) and thinking about insulating under the slab but only one panel width in from the stemwall. Hoping that gives us a bit of both benefits, which you mentioned. I do not have links handy but came across this idea in different posts/threads here on GBA.
Using an ICF stemwall would be the easiest and most cost effective way of doing that.