In short, not safely. Shipping containers are built to be stacked several units high, but that strength depends entirely on an even, load-bearing base beneath the bottom container. Soft or uneven ground undermines that from the outset, whatever the containers themselves are rated to carry. It’s one of the most common mistakes we see with first-time container setups, and it’s almost always avoidable with a bit of planning before delivery.
Why Ground Condition Matters So Much
A loaded shipping container can weigh several tonnes, and that weight is carried through the four corner castings at each corner of the unit. On firm, level ground, that load is spread evenly and the structure stays stable. On soft ground, one corner can sink slightly more than the others, twisting the container frame out of true. Once that happens, doors can jam, stacked units become unstable, and the risk of a container shifting or toppling increases significantly.
This isn’t just a theoretical risk. Even a small amount of settlement, just a few centimetres at one corner, can be enough to throw a container’s frame out of alignment. Containers are engineered to flex and carry weight vertically through their corner posts, but they’re not designed to cope with uneven support underneath. Once the frame is under that kind of stress, it can affect everything from door alignment to the long-term structural integrity of the unit.
What Counts as Soft Ground?
- Grass or turf without a hard base beneath it
- Recently disturbed or backfilled earth, which hasn’t had time to settle and compact naturally
- Ground that becomes waterlogged after rain, even if it seems firm when dry
- Loose gravel or hardcore that hasn’t been properly compacted before use
- Areas close to drains, soakaways or underground services, where the ground may have been excavated previously
It’s worth noting that ground condition isn’t always obvious just by looking at it. A patch of ground that seems solid in dry summer weather can turn soft and unreliable after a few weeks of autumn or winter rain, which is why proper preparation matters even on sites that look fine on the day of delivery.
How to Prepare Ground for Stacked Containers
Level and Compact the Base
The ground needs to be levelled and compacted before delivery, removing any soft patches or debris that could create an uneven surface underneath the container. This usually involves excavating any loose or organic material and replacing it with a compacted layer of hardcore or aggregate, giving the container a firm, stable footing.
Use a Proper Foundation
Concrete pads, railway sleepers or purpose-made steel bearers are the most reliable way to spread the load evenly, particularly if containers are being stacked two or more high. Concrete pads under each corner casting are the most robust option for permanent or long-term stacked setups, while sleepers or bearers can work well for shorter-term arrangements. This is worth planning before delivery rather than working out on the day, since retrofitting a foundation under an already-positioned container is far more disruptive.
Check Drainage
Ground that’s fine when dry can turn soft after heavy rain. Making sure water drains away from the container base helps keep the ground stable through wetter periods, and it also protects the container’s underside from prolonged exposure to standing water, which can accelerate corrosion over time. A slight fall away from the container, combined with adequate surrounding drainage, makes a real difference over the life of the installation.
Consider the Number of Containers Being Stacked
The more containers you’re stacking, the more critical ground preparation becomes, since the load on the ground increases with every additional unit. A single container on soft ground might settle slightly without causing major problems, but a two or three-high stack on the same ground is far more likely to develop serious issues. If you’re planning a multi-container stack, it’s worth getting the foundation checked by someone experienced in this kind of setup before committing.
Our guide on what ground preparation is needed before container delivery covers this in more detail, and our post on how to move a storage container is useful if you’re relocating a unit that’s already on site, whether because the ground has proven unsuitable or your storage needs have changed.
Getting Access Right
Ground condition isn’t the only factor. Delivery vehicles need a clear, firm route to the drop-off point too, and the same soft-ground issues that affect a stacked container can also cause a delivery vehicle to become stuck or unable to safely lower the unit into place. Our transport guidelines page sets out what’s needed for different vehicle types, and if you need secure steps up to a stacked or raised unit, our container stairs are worth considering as part of the wider setup.
Get Advice Before You Order
If you’re not sure whether your site is suitable for a stacked container setup, talk to our team before delivery. It’s much easier to sort ground preparation in advance than to move a container once it’s settled unevenly, and a short conversation upfront can save a lot of disruption later on.