Dry from the ground up
Your shed comes with a very solid floor.
The floor is made with 18mm weather-proof plywood (WBP). A coat of wood preservative on the top surface gives an extra layer of protection. This plywood is fitted to tanolised timber bearers and then a waterproof membrane is fitted between: This waterproof membrane also laps up around the edges where it is joined with the same membrane that is fitted within the walls.