I think a lot depends on the construction of the shed. If it has a framed floor with timbers or runners underneath, then it should be easy to move. I worked for a modular building company in the 80s, and we used to build sheds inside a factory and then deliver them (using a rollback car carrier) to customer's yards. All of the sheds had a framed floor with two or three 2x4 or 4x4 runners going the length of the shed (crosswise to the floor joists).
Some tricks we used:
1) on the truck bed, on pavement, or on the factory floor, you could jack the shed a little and place 1" diameter iron pipes under the runners. With a gentle push, the sheds would easily roll, and it was just a matter of cycling the pipes back around under the shed every so often.
2) on grass or slightly uneven ground, we'd jack the shed and place round landscape timbers (about 4-6" diameter) under the runners. These are available in all sorts of forms -- as fence posts, etc. Two guys could easily move the shed around this way, and it was also easy to slide sideways on the rollers.
3) on sloppy ground, we'd use one of the approaches above, but put down skids or sheets of plywood first.
4) if you need to winch or pull the building, weld up a little "F hook" out of angle iron that will grab the first few floor joists and provide a secure pulling point down low. We had ones with 2-3 wings going back 2-3 floor joists, with a little screw on the front to snug up against the outer joist and keep the hook in place. From there, the truck winch or a come-along, or a chain to a truck/tractor pulling point would move the shed on rollers.
5) for final maneuvering, a doubled up 2x4 and some blocks makes a great big lever arm that you can use to "walk" the building inches at a time.
6) in winter, we actually moved a few buildings by sliding them on snow with old snow-mobile skis under the runners! Obviously, that is highly dependent on the right conditions -- frozen ground and just a few inches of snow.
7) one time in a tight space, we jacked the shed and then slid some old wheeled farm implements underneath (couldn't begin to tell you what they were). Then an old timer towed the shed into place with his tractor. I do remember the guy had about 5-6 sheds in his yard already!
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If the shed did not have a solid floor, then I'd suggest jacking the shed and making a temporary frame or platform underneath, then move it on that frame. That's generally how houses are moved.
I found an old Polaroid of a shed I moved, see attached (this was just prior to strapping everything down on the truck). I think I was only 18 or so when I had that job. I'd kill to have that truck today -- it was sweet.
Good luck! Be creative!
