Working on an agricultural building (slab on grade, 1 1/2 floors). The exterior is almost complete, and now it's time to move indoors. I'm planning to keep the concrete floor (will paint it later), there will be gypsum on the ceiling and OSB/gypsum on the walls. I will also install horizontal 45x45 before OSB/gypsum.
What is the best/optimal/simplest work order for the ground floor? I was thinking of the following:
- Insulation 145mm exterior walls
- Age-resistant plastic exterior walls
- Batten ceiling
- Gypsum in the ceiling
- Horizontal 45x45 on exterior walls
- Frame interior walls
- OSB/gypsum on one side of interior walls
- Electrician/plumber
- Insulation 45mm exterior walls
- OSB/gypsum on exterior walls
- OSB/gypsum on interior walls
- Sit down and have a beer

How would you do it? Tips are gratefully received!