I have a 30' x 50' with insulation in the walls, 5/8" plywood on the inside wall, 1/2" plywood on the outside with sheet metal on it. From the road it looks like a metal building. 7/16" plywood on ceiling with six inches of fiberglass insulation. I bought a used 3 and half ton AC unit, duct work and all installed for $1500. When it's 85 in the shop, like it was today (99-101 outside) I can run the unit for 20 to 30 minutes and cool down the shop. It does not drop the temperature much but it dry's out the air and it feels cooler. If it cools it down to 78 to 80 it feels good while we work in the shop.
Last summer I added on a 20' x 50' to the back of the shop. Now the shop is 50' x 50' but I have not put insulation into the new part, nor did I add AC. It's about 18 degrees hotter in the new part during the day.
I think the screen door would be great in the fall and spring.
Dwight
I did build a bathroom in the new addition.
