Plumbing penetrations can be tricky to plug with rigid foam board; SPF seals seamlessly around obstacles with a few passes of the spray gun.
The foam can be walked on only minutes after spraying, permitting multiple layers without significant delay. The 2x4 at this chimney base will be removed after spraying to provide the code-required gap between the flue and the foam.
Cured foam sticks tenaciously to most surfaces. Plastic food wrap protects these plumbing stubs from the overspray.
When a finished basement interior is planned, the foam can run up the walls to create a thermal break at the slab edge.
In an unfinished basement, rigid foam board provides a neat thermal break at the slab's perimeter. The excess can easily be trimmed flush with the finished slab and sprayed with a thermal barrier coating.