Replacing Shed Floor

[TheClot]

I've got a 6' x 3' Tongue & Groove pent shed with a rotten floor. I'm planning to replace the floor with 18mm OSB3. Current plan is to tip the shed on its side, screw in OSB to 'walls', then re-position on fresh base.
Would welcome any comments on this, including, is it best to rest shed on large side (ie 6' x 6') or one of the ends (6' x 3')? Or is there any easier way? Thanks