A properly designed and build wood floor (and foundation) will hold thousands of pounds with no trouble.
There are 4 items that determine the strength of your wood floor
- Number and spacing of foundation supports, (skids) usually 2 or 3, spaced at 4 to 7 ft on center
- Floor joists size, usually 2×4, 2×6 or 2×8
- Floor joist spacing, usually 12 to 16 inches on center
- Thickness of floor covering, usually ¾ inch plywood or OSB, square edge or tongue and groove
Your storage shed plans should specify the floor joist size and spacing. However if you want to build an even stronger floor, either use larger joists or more of them (closer on center), and/or more skids.
Most wood floors are built to these specifications
- 8 wide sheds, 2×4 joists 16 inch on center, 2 skids (4×4) at 5 ft on center
- 10 and 12 wides, 2×6 joists 16 inch on center, 2 skids (4×4) at 6 to 7 ft on center
These are the specifications I recommend and show in my FREE Shed Building Guide. Floors built to these specifications will hold a lot of weight.