help with skid foundation for shed

[PoorOwner]

I wanted to know if I am using the 4x4 for skids, is laying down 2 of them (86" long and parallel to each other) enough for a 7'x7' shed platform? They will be put about 48" - 50" apart. Then the floor joists would be 2x6 it's a lot easier to level 2 skids than 3 I think..

Also, I want to put some gravel below each concrete block say 8"x16" holding the skids, how big should the gravel "pit" be under each block?
I am in California clay soil.

Last question is that the shed is plastic floor and will sit on the PT plywood, It occurs to me water could get in between the plywood and shed plastic floor (though not likely), should I be drilling a series of holes on the plywood incase.. for if I spilled liquid inside the shed in a rain storm where the rain falls sideways.

 

[TexasT]

The last one we built got two 4x6 "skids", then we built the 2x6 frame/floor on/attached them. We cut a bevel on the bottom of each end to help it "skid".

 

[TractorJeff]

Width of skids, number of skids and distance between them is based on weight inside.
If it doesn't freeze and snow in your are, my opinion is sitting on concrete blocks would be good enough.

 

[bad_idea]

2x6's spanning 4' will hold quite a bit of weight, you should be good there. When I built my metal shed the instructions said to spread roofing tar along the seam of metal shed to wood floor for waterproofing. Perhaps that would work for you?