Not all sheds need to be attached to the ground. Many wooden sheds will rest solidly on concrete blocks or similar foundations, even beams set on compacted gravel. But lighter sheds, especially those of metal or vinyl, usually need to be attached in some way and many homeowners are more comfortable with sheds that are solidly secured into the ground. There are three basic ways to attach a shed to the ground: concrete slab, pier and beam foundation or ground anchors (also called tie-downs).
Form and pour a concrete slab for the surest foundation to attach a shed to the ground. Excavate the shed area, fill it with compacted gravel, then cover it with concrete. Secure the shed to the slab either with bolts set upright in the concrete while it is being poured or with concrete nails driven through wooden base plates into the slab. Bolts will work with either wood or metal and vinyl sheds; drill holes in the base plates or bottom rails to match the bolts, then fasten the shed with washers and nuts.
Set pre-cast concrete piers in the ground in holes or build forms and pour concrete for piers; either style should have metal brackets in the concrete to hold beams that support the shed. Dig holes for pre-cast piers with a post-hole digger and set them in place; secure them either by replacing dirt or by pouring concrete in the hole around them. Install the beams with nails or screws in the brackets and nail a framed floor to the beams.
Use ground anchors, especially with metal or vinyl sheds, which are lighter than wood. Pick a type of anchor to conform to the shed; most metal or vinyl shed kits either come with anchors or with recommendations for anchoring. Dig a hole, put an anchor in it and set it in concrete or use anchors with are driven or screwed into the ground. Secure the shed to the anchors with heavy wire with eyelets on the ends and a turnbuckle to tighten the wire.