The 13-Step Site Preparation & Foundation Process

6-Inch Minimum Excavation — Nothing Organic Remains Beneath The Pad

All sod, root systems, organic topsoil, and biologically active material are excavated from the full 14×16 rough pad area to a minimum depth of 6 inches. In Greater Cincinnati's clay-heavy soils, excavation may extend to 8 or 10 inches to reach stable inorganic mineral soil. Sod and clean topsoil are stockpiled for reuse in finish grading around the completed building.

Inspect, Regrade & Compact The Native Subgrade

After excavation, the exposed subgrade is inspected for soft spots, loose fill, trapped roots, wet pockets, and unstable soil. Any unsuitable material is removed and replaced or reworked before the base layers continue. The subgrade is then regraded for positive drainage and compacted in overlapping passes with a plate compactor.

This step creates the firm, consistent bearing surface that supports the fabric, stone base, moisture barrier, foundation beams, and floor system above it. The goal is not simply to make the ground look flat. The goal is to create a stable prepared subgrade that does not pump, rut, settle, or hold water beneath the finished building.

Separation Fabric — Keeping Stone Clean, Stable & Structurally Useful

Commercial geotextile stabilization fabric is rolled out across the prepared 14×16 pad area before any stone is placed. The fabric separates the compacted soil subgrade from the crushed stone base above it, helping prevent the stone from sinking into clay, mud, or softened soil over time.

Fabric seams are overlapped, pulled flat, and extended across the full prepared pad area so the gravel base remains clean and separated from the native soil below. The fabric is installed before stone placement, not after.

Pressure-Treated Perimeter Containment — Holding The Stone Base In Place

Pressure-treated perimeter containment timbers are installed around the full prepared pad area before the stone base is placed. The containment frame helps define the gravel pad boundary, holds the crushed stone in position, protects the clean edge of the foundation base, and helps prevent gravel from migrating into the surrounding yard over time.

The perimeter is set to the planned pad layout and checked against the batter board references. Where site conditions allow, the timbers are secured with driven rebar stakes to help maintain alignment and resist movement during stone placement, grading, and long-term use.

6-Inch #57 Washed Limestone Base — Drainage, Bearing & Stability

A minimum 6-inch layer of #57 washed limestone, or a comparable clean angular stone, is placed across the full prepared pad area inside the perimeter containment. The stone is spread evenly over the geotextile fabric and raked to the planned elevation before final consolidation.

The clean angular stone creates a stable, free-draining base beneath the moisture barrier, foundation beams, and floor system. Because the stone is washed and open-graded, water can move through the base instead of collecting directly beneath the building.

Level, Seat & Consolidate The Stone Base Before Moisture Protection Begins

The #57 washed limestone base is leveled, checked against the planned elevation, and consolidated across the full prepared pad area. The stone is raked, adjusted, and seated so the base is even, stable, and ready to receive the moisture barrier and foundation beam layout.

Clean angular stone does not compact like soil or crusher fines. Instead, the goal is to settle, seat, and stabilize the stone so the pieces interlock, high spots are corrected, low areas are filled, and the finished surface supports the layers above without shifting or rocking.

Moisture Barrier Over Stone — Separating The Wood Foundation From Ground Moisture

A 10-mil polyethylene moisture barrier is placed over the consolidated stone base before the foundation beams are set. The barrier is laid flat across the prepared pad area, with seams overlapped and taped where multiple sheets are required.

This layer helps reduce ground moisture exposure beneath the structural floor system. It is installed after the stone base is prepared and before the 6×6 pressure-treated foundation beams are positioned.

Five equally spaced 6×6 Ground-Contact Foundation Beams — The Structural Base That Carries The Floor

Five equally spaced 6×6×12' ground-contact pressure-treated foundation beams are set on top of the moisture barrier and aligned with the actual 10×12 building footprint. The beams run in the 12-foot direction and are spaced evenly across the 10-foot width to provide continuous support beneath the floor framing.

Each beam is checked for straightness, alignment, spacing, and elevation. The beam system must be level, co-planar, and properly positioned before the 2×6 floor joist system is installed above it.

2×6 Pressure-Treated Floor Joists — Framed 16 Inches On Center With Blocking

The floor system is framed with 2×6 ground-contact pressure-treated joists installed at 16 inches on center. Rim joists define the outside perimeter, and the joists are laid out square to the 10×12 building footprint over the four 6×6 foundation beams.

Center blocking is installed between joists to help control twisting, improve floor stiffness, and lock the joist system together before the plywood subfloor is fastened. The floor frame is checked for squareness, consistent spacing, and solid bearing before sheathing begins.

3/4" Pressure-Treated Plywood Subfloor — Framing-Ready Platform Complete

The completed floor frame is covered with 3/4" ground-contact pressure-treated plywood. Sheets are laid out, aligned, fastened to the 2×6 floor joist system, and checked so the finished platform is solid, square, and ready for exterior wall framing.

At this point, the site preparation and foundation sequence has created a layered system: cleared ground, excavated subgrade, stabilization fabric, clean stone, moisture protection, 6×6 beams, 2×6 joists, blocking, and a structural plywood subfloor.