We're getting ready to build 40x60 with a second level. Multiple drains in the floor. 10' ceilings in the first floor, 2' knee walls in second floor to minimize lost space on the outside of the second level. 12' section on 1 outside wall on 1st floor to accommodate skinning machine. Spray foam insulation, wood stove and propane heat. Multiple drains in the floor. Will be partitioned off to accommodate trap storage, freezers and utvs on front end. Back end will be skinning area and lure making area. Upstairs will be overflow storage

Mike a 4' knee wall would be better, less knee work to get stuff back. My work shop is 30x50. wish it was 40x60 with attic.