So your "porch" is going to be the same height as the building eave? So how does this space be effective for taller equipment?
Height definitely has a direct bearing on cost.
I'm probably not explaining it right. I plan to build a normal shop with 12 foot walls and a 10 foot tall, 12 foot wide door on one end. Then put an 10x10 roll up door on the other end because I already have it. The shop will have concrete floors and leanto's off of each side. Shop will be 30 feet wide and 48 feet long, plus the leanto's, which I will make as big as I can, but that will depend on how much flat space I have when I get to that point. I'm still removing trees.
So basically a 30x48 building with 12 foot walls, 4:12 pitch metal roof on wood trusses with a flat ceiling that I will fill with blown in insulation for the shop.
Then I will extend the roof line another 48 feet to create a covered gravel parking area for my tractors using these metal trusses.
Metal trusses - farm & garden - by owner - sale
Figuring the roof pitch, the width of the roof and the thickness of those metal trusses, I should have over 15 feet of open space under the trusses. 14 feet gives me plenty of room to drive my backhoe into there.
I will have enough room to double this if I decide to later on, for 96 feet. Or I could go just 24 feet to start, and keep adding in 24 foot lengths when I have the need and the money. I will set a post at 24 feet and run a gluelam beam to support the trusses. Trusses will be every 8 feet.
I should admit that I've been working on this plan for a few years now and it's always changing. So this is my latest version of what I want to build and it could easily change a few more times before I actually start building it.