Site Preparation for Shipping Containers

How to prepare a US site for a shipping container, ground prep, gravel pads, concrete foundations, drainage and mistakes to avoid.

Ground Preparation

Strip 4–6 inches of topsoil, compact the subsoil, install non-woven geotextile fabric. In freeze zones, extend below frost depth.

Gravel Foundations

6–8 inches of compacted ¾-inch minus crushed stone, sized to container footprint plus 2 ft margin. The default US foundation for 90% of buyers.

Concrete Foundations

Concrete piers ($800–$1,800) for permanence and ventilation; strips ($1,500–$3,200) for soft ground; full slab ($3,500–$7,000) when a permit requires it.

Drainage & Mistakes

Pitch 1–2% away from the container, add gutters on long-term installs, maintain a 4–6 inch air gap underneath, never set directly on dirt.

What surface does a shipping container need to sit on?

A container has four corner castings, that's the only point of contact with the ground. The surface needs to support the load at those four points and keep the container level over time. Three options work in practice. Compacted gravel (most common): a 15 to 20 cm layer of crushed stone, levelled and compacted, on undisturbed subsoil. Cheapest, easy to install, allows drainage. Concrete pads or pavers at each corner: four reinforced concrete pads or large paving slabs, levelled, with the container resting on its corner castings. Better for permanent installations. Full concrete slab: a continuous reinforced slab under the entire footprint. Most expensive, used for buildings or critical installations. Avoid placing directly on grass, soil, or asphalt, these settle, hold moisture, and cause the container to twist over months.

How level does the surface need to be?

The corner castings must be within 25 mm (1 inch) of each other in elevation, measured diagonally. More than that and the container's frame is twisted, doors stop closing properly, water pools on the roof, and over time the structural integrity is compromised. Use a long spirit level or a laser level across the diagonals after the container is placed. If it's out of level, the standard fix is to shim under the high-side corners with steel plates or treated hardwood blocks, then re-check. For permanent installations, take the level reading 30 days after placement and again at 12 months, surfaces settle, and a level container at install can become out-of-level by next summer.

Do I need a permit or building approval to place a container on my site?

Depends on the jurisdiction and intended use. Three common cases. (1) Temporary on-site storage during construction: usually no permit needed in most countries for a stay under 6 to 12 months. (2) Permanent storage container in a commercial or agricultural setting: often no permit if it's clearly mobile equipment, not a building, but check local zoning. (3) Container as a building (office, dwelling, retail): typically requires building permits, structural certification, and code compliance for habitability, this is no longer a container question, it's a building question. The single rule: if the container will be modified (cut, welded, electrified, plumbed) and used as occupied space, expect to need permits regardless of country.

How do I protect the site and the container from water damage?

Water is the single biggest long-term threat to a container installation. Four measures. (1) Drainage away from the footprint: the gravel bed or concrete pad should slope 1 to 2% away from the container so rainwater runs off rather than pooling. (2) Gutter or drip edge if the container is under any structure that channels water onto the roof. (3) Clearance underneath: the corner castings naturally lift the container 15 to 20 cm off the ground, preserve that gap. Don't let mud, leaves, or debris fill the underside, as it traps moisture against the steel and accelerates corrosion. (4) Roof inspection annually: the container roof is rated for water tightness, but pooling water plus dents plus UV will eventually create pinholes. Walk the roof once a year, clear debris, check for soft spots.

What's the full site checklist before the container arrives?

Eight items. (1) Surface prepared: gravel compacted, concrete pads cured, or slab finished, done at least 7 days before delivery for concrete. (2) Level verified: under 25 mm diagonal variance, measured. (3) Drainage installed: slope confirmed, no low spot under the footprint. (4) Access cleared: 25 metres straight approach for tilt-bed, lateral clearance for side-loader, no overhead obstructions under 4.5 m. (5) Setback respected: minimum 30 cm from walls, fences, neighbours' property, for door operation, ventilation, and maintenance access. (6) Power and water planned if you'll add services later: trench lines, conduits in place before the container blocks the route. (7) Anchoring planned if needed (high-wind areas, building code requirement): twist-locks or wire tie-downs to anchor points in the slab. (8) Delivery scheduled with your trucking company and a contact person on site for the delivery window.