I am building a 40 by 50 insulated stick-built shop that will be 14ft tall. I do not have the money to heat the floor. I am going to use the shop for car storage and working on cars. For those of you with a shop, what kind of heat source would to recommend? I am pondering a wood stove (although there may be some insurance/safety concerns), gas heat, or electric heat. Generally, the winters where I live have 10-15ish days of below freezing temps. For the sake of car care, I am not sure if I should try to keep the shop relatively warm or if I can get away with heating it only when I am working in the shop. Thanks in advance.