I have a small storage building and it needs some work like the floor
Related Discussions
Suggested Project Book
if the storage building is up on cinder blocks, you can lay plywood down for the floors.
If you put down plywood get the treated ones and try to go with about 1/2 inch thick, it will take more abuse and stay flat even if you get a leak in the roof or leave the door open and it rains. I have 1/2 inch in my shed that I have had for 17 years and it still is flat and in good shape even though I have a couple of leaks that I can't find in the aluminum roof.
Use precast patio block. Fill the spaces between with morter mix.