Plywood and Foam Assembly for Finished Basement Floor
We are finishing a basement and trying to end up with a floor that is carpeted. I’m considering foam board + plywood/osb subfloor approach in Martin’s article: https://www.greenbuildingadvisor.com/article/installing-rigid-foam-concrete-slab
How flat does the floor need to be for the foam + plywood/osb approach if the goal for the finished surface is just carpet? Can 1″ thick of XPS tolerate hills of 3/8″ and perhaps some shallow valleys? It seems pretty stiff, but I’m not sure if it conforms to the floor a bit over time.
I’ve read several articles about the foam + plywood approach but I’ve not seen the flatness requirements of the floor dealt with in any of them.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part