Preparing Ground for a Shipping Container

Why level matters more than you think

A container is a steel box that relies on being square. If one corner sinks, the frame twists, and the first thing you notice is that the doors no longer line up or the locking bars need a shove. Left long enough, water pools against the sills and rust starts where you cannot see it. Levelling the ground is the cheapest maintenance you will ever do.

What good ground looks like

• Firm: compacted hardcore, concrete, tarmac or well-established stone. Freshly dug or backfilled ground will settle unevenly.
• Level: within an inch or so across the footprint. Small differences can be shimmed; a noticeable slope cannot.
• Draining: water should run away from the container, not sit under it. A very slight fall across the site is better than a dead flat hollow.
• Clear: no drains, soakaways, septic tanks, service ducts or shallow cables under the footprint.

Supporting the corners

On decent ground, the simplest approach is a concrete paving slab or a short length of railway sleeper under each corner casting, bedded so all four sit at the same height. On a 20ft container that is four points; on a 40ft it is worth adding support at the midpoints as well, especially on softer ground or if you intend to load it heavily.

Avoid stacking loose bricks or timber offcuts. They move, they rot and they crack under point loads. If you need height, use proper concrete blocks laid on a compacted base, or pour small pads.

Common surfaces

Concrete or tarmac

Ideal. Check the slab is thick enough and in good condition, and remember that hot tarmac in summer can mark under corner castings. Slabs or steel plates spread the load.

Gravel or hardcore

Very common and perfectly good if it is compacted rather than tipped. A 4 to 6 inch layer of MOT type 1, whacked down, with slabs under the corners, gives an excellent base and lets water drain.

Grass and soil

Workable for a small unit, but expect settlement and seasonal movement. Strip the turf, dig out to firm ground, backfill with compacted stone and set the corner supports on that. On clay, do more rather than less - clay shrinks and swells with the weather.

Sloping sites

Either cut into the slope and retain the cut, or build the low side up on solid pads to bring the container level. Do not simply chock the low corners with whatever is to hand, and do not let the container act as a dam across a slope where water runs.

Airflow underneath

Lifting the container a few inches off the ground keeps the underside dry, lets air move and stops leaf litter and standing water rotting the base rails. It also makes the floor warmer, which helps with condensation. Keep vegetation cut back around the unit for the same reason.

Practical prep checklist

1. Mark out the footprint, adding room to walk round and the door swing at one end.
2. Check nothing is buried under the footprint.
3. Clear vegetation and topsoil down to firm ground.
4. Compact a stone base if the ground is not already solid.
5. Set four (or six) supports, checking they are level with a long straight edge.
6. Make sure water can run away from the container, not under it.
7. Confirm the lorry can reach the spot - see the delivery access checklist.

After it lands

Open and close the doors before the driver leaves. If they bind, the container is not sitting square and it is far easier to lift and shim it there and then. Check the level again after the first winter, particularly on newer ground, and shim if anything has settled.

Not sure your ground will do? Send photos and a rough description through the contact form and we will tell you what we would do. If you are still choosing a unit, start with container sizes explained or browse new and used stock.