Prepare a Strong Foundation for Your New Building

Block site prep is a straightforward option for locations where the building can be set on skids and leveled with solid concrete blocks. The ground should be firm, reasonably level, and able to shed water away from the building.

• Use solid concrete blocks measuring 8″ × 16″ × 4″.
• Place blocks at the front and back of every skid.
• Add intermediate blocks along each skid so no support points are more than 6 feet apart.

Remove soft soil, vegetation, roots, and debris from the building footprint. Level each support point carefully so the skids bear evenly and the doors operate correctly after installation.

A limestone pad creates a stable, well-drained base beneath the full building footprint. It is especially useful where runoff, soft soil, or seasonal moisture could affect the site. This is our recommended option for most sheds and barns.

• Install 4 inches of #57 limestone.
• Extend the limestone 12 inches beyond the building on all sides.
• Use optional 4 × 4 retaining boards where needed to contain the stone and define the pad edge.

Excavate and grade the area as needed before placing the limestone. Compact the stone evenly and verify that the finished pad is level while still allowing surrounding surface water to drain away from the building.

A concrete foundation provides a durable, permanent base when the building design or intended use calls for one. Final elevations, reinforcement, thickness, and local code requirements should be determined before the pour.

• Pour the concrete pad ½ inch smaller than the building dimensions.
• Install treated plates at the perimeter.
• Fasten the treated plates to the concrete using approved anchors or bolts.

Confirm the exact outside building dimensions before forming the pad. The concrete must be square, level, and fully cured before installation. Coordinate any plumbing, electrical conduit, drains, or embedded hardware before concrete is placed.

A post platform foundation supports the building above grade and can help on sloped or uneven sites. Because the post layout carries structural loads, locations and elevations should be confirmed before digging.

• Dig post holes 32–42 inches deep.
• Place post pads or concrete in the bottom of each hole.
• Install the posts and connect bolted cross-beam joists to create the supporting platform.

Set all posts plumb and at the correct height. Check the completed platform for level, square, and secure connections before the building is installed. Local frost-depth and structural requirements may affect the final design.

When a shed is attached directly to a concrete slab, the wall system needs a raised edge that helps secure the structure and separates wall materials from surface water.

• Provide a 4-inch reinforced curb for a shed attached to a slab.