We're planning how to finish our basement, and haven't been able to figure out something related to insulation.
The home's in Minnesota, and was built in 2008. XPS insulation (installed by the builder) covers all concrete surfaces, and I haven't seen any indication of any sort of moisture intrusion. I can't see what's behind the XPS, though I took photos during construction and it doesn't look like there's anything but concrete there.
Here are my questions:
- When framing the exterior walls, should I add any sort of vapor barrier between studs and XPS, or will the existing XPS facing suffice?
- Should I add batt insulation between studs, or leave those interstices empty?