By its very nature, a metal outdoor shed is a lightweight structure. If it is not anchored securely to the ground, it can be moved around by a strong wind. Any metal building should ideally be positioned so it does not sit in a naturally windy place, but, to be safe, it will still be necessary to give the shed an anchoring system.
The best way to anchor a metal building is to set the four corners on concrete piers that are located at each corner of the building. These blocks of concrete actually serve dual purposes, for they not only anchor the lightweight structure to the ground, but also provide four corner posts to support the building. When you pour the concrete posts, make certain that the tops of all four are level. Each pier should be at least one foot square, with a depth that goes at least two feet into the ground. Properly constructed concrete piers should keep the shed securely fastened in place through most inclement weather. Each pier needs a bolt placed in a vertical position at the top while the concrete is still wet. The bolt will then be attached to a block of wood, which is held tight to the surface of the concrete by a few washers and nuts. The floor of the metal shed is then secured to the blocks of wood, located at each pier. You may also wish to build a 2 x 4 frame floor to support the metal shed, but this is not always necessary.
As an added precaution, insert metal anchors into the ground, and then use a cable to connect the anchors to the shed. These auger-type devices enter the ground in corkscrew fashion, and a guide wire is attached to the tops of the anchors from the shed.These anchors add some protection against high winds, but should not be the only means of attaching the metal shed to the ground. A combination of both concrete piers and metal augers will work very well in most weather situations.