Hello GBA community. I am adding an addition to my existing raised ranch house in climate zone 5.  The addition consists of 3 concrete slab levels. I plan on adding R-10 rigid foam to the exterior perimeter stem walls (on both sides). The exterior is also getting self adhering waterproof membrane and dimple mat. 

Should I also consider doing anything regarding waterproofing or insulation on the interior stem walls ? In the attachment, #1 is slab on grade (rock ledge) of master bedroom, #2 is an elevated slab 1′ 10″ higher than slab # 1 and equal height to existing home subfloor (floor joist over crawl space), and elevated slab # 3 is 1’10” higher that existing home subfloor. 

Essentially Slab # 1 (master bedroom/ bath) will be below slabs #2 & #3. I don’t expect any issues with high water tables or water intrusion. 

Hope this is enough info, and if not, I will gladly submit additional info.  

Thanks,

Mike – Hudson Valley, NY