No recommendations on construction. However, I started remodeling my unheated garage last year (NY as well) and this is the first winter I’ve worked out in there. Please don’t forget how cold it gets. I thought “eh, I’ll work up a sweat and won’t mind”. Boy was I wrong. It gets so cold the barbells feel like frostbite after a set of 12. Insulate, plan on heating, and make sure any gaps are filled in