I am building a home with a 3 car garage which I hope to use part of it as a workshop. I did not think to ask for the outside walls of the garage to be insulated. Would it be a good idea to get the walls insulated. I live in Arkansas where it gets moderately hot in summer and moderately cold in winter. Is it too late to insulate the walls now that the drywall is up? I am going to get an insulated garage door as the cost difference was not much.Paul