Detailing basement insulation
I live in central NH zone 6 and I have a question about details for insulating my basement by myself. The house is a year old and during last summer the basement reached 64F and 80% RH until I got a dehumidifier. The town calls for R-15 cont./R-19 cavity wall, so I am planning 3” of XPS or Polyiso and 1.5” XPS then subfloor over the slab. My question is about my PVC waste line which is attached to the foundation perimeter wall. I can get 1” of rigid foam behind it, but that’s all. Do I need to move this line away from foundation, or is there an alternative?
Second question is about the rigid foam on the slab around interior staircase and support walls. Does the staircase need to be removed (yikes) to be raised up to the new subfloor or do I have other options.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part