So typically i would work on 400mm centres for both types of support using 18 20mm thick decking.
Proper shed floor joist support.
So what is the proper shed floor joist spacing.
If your storage shed is going to be larger then you will want to put in a middle support beam that goes the opposite direction of the way your joists are hanging.
Providing more support and rigidity than cross bracing solid blocking is a reasonable alternative but can be an obstacle for running plumbing pipes and electrical wire between floor joists.
Also cut your 4 x 4 skids to length.
Cut all floor joists to proper length along with your 2 rim joists and two band boards and skids.
The amount of weight a 2 8 can support is going to depend on the span of the joist and how far apart it is from the next joist.
After cutting all lumber mark off your two band boards for joist layout at 12 on center.
Gather the proper lumber to cut your floor joists rim joists and 2 two band boards and 4x4 skids.
To square the area measure 3 feet along one string and 4 feet along the adjacent string.
Set batter boards and mason line to mark the perimeter of the posts that support the runners.
Solid blocking should be used where floor joists overlap over beams.
Since you can span 13 with a 2 8 spf joist on 16 inch centers but you ultimately decide to only span 8 feet with your joist on 12 inch centers the weight.
The runners are set back from the shed frame the distance of the overhang.
The spacing of both joists and bearers will be governed by the type of structural floor decking that is used.
Although a 2 6 can span 11 10 a span 8 feet or longer should have a center support beam.
The distance between the two points should be 5 feet.