I can't address your codes;but I have an 8 X 12 that just sits on cinder blocks . It hasn't moved in 20 years . It has built in shelves holding about 600 lb of stuff which may help. When Harvey hit ,we got 40" of rain in a couple days and the only problem was the end of a 100' pine laid on it ( didn't move it ). I figure if it blows away I will have bigger problems than a garden shed. I should be clear, I am in the "piney woods" and storm damage is nearly all the result of falling trees not direct wind. If you are on the plains of Kansas , that is different.
