What do I need to make a shed office usable year-round in Michigan?

We offer spray foam insulation that's a game-changer for year-round use. It seals gaps, prevents drafts, and works especially well under the building for floor insulation, since the building sits elevated. Spray foam under the floor is one of the best investments you can make if you plan to finish the interior later. A ductless mini-split handles heating and cooling in one unit. After that, it's details: weatherstripping on the doors, maybe a small area rug over the floor, and good window placement so you're not fighting glare on your screen.