IDK about US wooden houses, but here isolation for old building is usually done on the outside on the top of previous finish with styrofoam or mineral wool: htt

IDK about US wooden houses, but here isolation for old building is usually done on the outside on the top of previous finish with styrofoam or mineral wool: https://d-art.ppstatic.pl/kadry/k/r/1/70/9e/60644af2aec93_o_full.jpg https://d-art.ppstatic.pl/kadry/k/r/1/70/9e/60644af2aec93_o_... >economically unrealistic to do just to save on HVAC That depends on how much the HVAC costs... I saw some videos from last USA freeze where people had ice (!) inside of their homes - I doubt heating that is in any way economical.