PerryChase, OSB is not suited to being exposed directly to the elements. It is fine under the roofing felt and shingles, and I find it great on the exterior walls when I’m nailing on vinyl siding. But if OSB gets wet, over time it puffs up and delaminates. The roof on my shed is engineer trusses on 2′ centers, then OSB sheathing, then roofing felt, then shingles with roof vent. The walls are 2×4 studs, then OSB, then Tyvek wrap, then vinyl siding. Instead of concrete I laid down large stone, then length ways 16′ (end to end) 6″x6″ treated beams (4′ on center), then 16′ 2×4 treated for floor joists on 12″ centers, then 3/4′ treated plywood. I can jump up and down on the floor and it is rock solid. I bought all of my supplies from Lowes. I think I spent around $5000 building the super shed. $1000 of that was for two pairs of double steel doors (one double door at an end and one on one side). I then partition the building, giving the wife 1/3 and I took 2/3 (I have more junk…motorcycles, the tools to build the shed, the tools to tile our floors, etc, etc). As a comparison, I got a price quote for a pre-made shed from a local builder. The cost of a new 14 x 24 shed, delivered was around $6600. So, building it myself, mine cost less and it is 16 x 30.