I built this wood shed with slightly used pallets from a local beer distributer, all the same size. I started by constructing a solid, heavy-duty deck with 6×6 timbers to support the heavy weight of the firewood I planned to store inside the shed. Then I used long 2×4 studs, trimmed them slightly on my table saw to fit inside the pallets, and then slid the pallets onto them, two per pallet stack. Then I erected the walls and bolted them to the sides of the 6×6 timbers at the floor. Finally, I put on a roof.
This wood storage shed was cheap and easy to build, and it lets a lot of air in to dry the firewood. — Tom Helm