Foundations for Your Gym In A Tin – What Does It Sit On?

One of the most common questions I get is:

“Matt, what does the container actually sit on?”

And the honest answer is — it depends on your ground.

Every site is different. Soil type, drainage, slope, access — they all matter. The good news is there are clear, proven options depending on your ground conditions. So let me talk you through them in order of simplicity and ground strength.

If you already have a solid, level surface such as an existing concrete slab, a concrete driveway or a tarmac car park, then we can often use jack pads. A jack pad is a heavy-duty adjustable support that sits under each corner of the container. It allows us to level the unit precisely and it’s clean, fast and a great option when the base is already strong and flat.

Another very common solution, especially on softer garden ground, is concrete padstones. These are 300mm by 300mm by 300mm concrete blocks placed under the key load points of the container.

For a 20ft Pod 20, you would need 6 padstones in total — one under each corner and two in the centre of the long sides.

For a larger Pod 60 made from three joined containers, that increases to 12 padstones.

Padstones spread the load effectively while keeping groundwork relatively simple compared to pouring a full concrete slab. It’s a neat middle-ground solution and works very well on many domestic sites.

If your ground has good natural bearing capacity — firm, stable soil — then we can go even simpler.

In this case we lay a geotextile membrane directly onto the ground. This stops weeds and separates soil from the structure. On top of that, we install oak railway sleepers measuring 2400mm by 200mm by 100mm. These are positioned at 1200mm centres.

For a Pod 20, you would need five sleepers.

This spreads the load evenly, keeps the container lifted slightly off the ground and allows airflow underneath. It’s cost-effective, quick to install and perfectly suitable when the ground conditions are right.

If the ground is softer or slightly uneven, then we step things up.

For medium ground bearing conditions, we excavate the site to a depth of 150mm. We install a geotextile membrane, then lay 150mm of compacted MOT Type 1 or scalpings. This material is mechanically compacted to form a solid sub-base. Oak railway sleepers are then installed on top.

The compacted MOT creates a stable, load-bearing platform that reduces movement over time. This is a very common solution in garden installations where the soil isn’t poor, but isn’t perfect either.

If the soil is weak, clay-heavy, waterlogged or prone to movement, then we go for the most robust option.

In poor ground bearing conditions, we excavate to a depth of 400mm. A geotextile membrane is installed, followed by 150mm of compacted MOT Type 1 or scalpings. On top of that, we pour a 250mm ground-bearing concrete slab reinforced with two layers of B-Mesh steel reinforcement.

This creates a fully reinforced structural base that will not shift or settle. It’s the most substantial solution and gives complete long-term stability.

So which one is right for you?

There isn’t a one-size-fits-all answer. We look at your ground condition, drainage, slope, access and intended use. From there we recommend the most appropriate and cost-effective solution.

The important thing to understand is this — once the base is properly prepared, your Gym In A Tin can be delivered, positioned, connected to power and ready to use within hours.

No months of messy construction.

No long disruptive build process.

Just smart groundwork and a plug-and-play gym.

If you’re considering a container gym and want honest advice about your site, just get in touch. I’ll happily talk you through the best foundation option for your ground.