I am giving in and doing a cool room. Using an existing block building. Building is 12 feet by around 30. Built like a lean to off of another building. One of the long wall is 6’6” and the other is 8’ tall. am wanting to use one 25000 btu unit. I’ll be insulating with spray foam. The guy who is going to spray it said to frame walls with 2x6. So I’ll be doing that on three block walls and I’ll have to build a wall to close it off. I’d like to go as long as I can since after insulating it’ll be closer to an 11 foot wide room. Thoughts on how long to make this room to effectively cool it and maximize space? One steer will be in it