I have a 1300 sq.ft. unvented concrete block crawl space, with a concrete floor, in northeast Ohio. The crawl space is about 5 ft. high, with about 4 ft. below grade.
Which would be more efficient for keeping the house warm (or "comfortable") - insulating under the floor of the living space with R19 batt, or insulating the inside of the crawl space walls with 2in. foam board? If you can give me a brief explanation of why it would also be helpful.