Are you curious about your options for underground storage using prefabricated steel?

Whether you’re storing anything from water, fluid or gas, to seeds, cardboard boxes, utility items, and everything in-between, a prefabricated steel substructure can be an ideal way to construct below-ground.

This is because unlike more traditional methods of below-ground construction, prefabricated steel substructures won’t leak or crack over time. They can also be built to much tighter tolerances (+-3mm) and can be installed 70 – 80% faster on-site.

TIP: Want to know more about prefabricated steel? Read my recent blog: ‘What is Steel Prefabrication Below-Ground and How Does it Work?’.

So, what are your options when it comes to prefabricated steel underground storage?

Well, as a specialist subcontractor who deals exclusively in prefabricated steel substructures, I’m going to talk you through all of your main options below – along with finishes, fixtures and fittings.

1. Water, chemical or fluid storage

If you’re storing any kind of fluid, a prefabricated steel substructure is without a doubt the most reliable method, as it’s built similarly to the hull of a ship – so, you can be confident it won’t leak over time.

Your main options for this type of storage using prefabricated steel are either a sump or bespoke substructure. Alternatively, you can use a prefabricated steel substructure as an interceptor tank or catchpit.

TIP: For more on these options, check out our Wide Lane and Floorspan case studies.

2. Storage for food or consumables

If you’re looking for a safe, dry place to store food or consumables, again a prefabricated steel substructure is a great choice, as this innovative method doesn’t just stop water from getting out – it stops it from getting in (a common issue with underground storage).

In the past, our substructures have been used for clients to store seeds and coffee beans – check out this case study to learn more about one project in particular. See below for more about different finishes that might suit your project best and keep your consumables fresh.

3. Machine storage

We often construct sumps or substructures with the sole purpose of positioning machines to be positioned into, allowing the working platform for operatives to be at ground level – rather than elevated on a platform.

There are various fixtures and finishes that can provide you with a wealth of options for machine storage, and all prefabricated steel substructures are built to be bespoke, to your own requirements – regardless of the size needed.

TIP: For a better idea of machine storage, check out our real-life examples in the form of our recent case studies – in particular, the London Taxi Company, Heathrow airport, and Northfield.

4. Foam blocks

Another use for prefabricated steel is a gym landing pit, and we’ve already constructed these for a couple of clients. Essentially, we built substructures or sumps to store foam blocks, which then allow gymnasts to land safety into landing pits.

We’ve actually put together a couple of case studies to give you a better idea of how this looks, and how it works in practice (check out our Lovells and Witham Gym case studies).

Further options for fixtures and finishes

Here are all of the finishes we can complete with a bespoke prefabricated steel substructure:

  • Mild Steel Structures
  • Painted finishes
  • 2 pac gloss
  • Hardwearing floor finishes
  • Non-slip floor finishes
  • Waterproof/swimming pool paint (rubber-based)
  • Galvanised steel
  • Stainless steel structures (304 grade or 316 grade)

Prefabricated steel substructures can also be built to incorporate various different fixtures or fittings – such as factory bolts, unistrut or captive nuts. Insulation is another great option if your substructure is to be used as a habitable space.

If you’re not sure what you need, we should be able to advise you further once we get a better understanding of what your substructure, sump or storage facility is going to be used for.

TIP: We offer a complete design package, which involves tailoring the requirement to your budget and finding the most economical solution for both long and short-term.

Advice from a specialist subcontractor

Reckon a prefabricated steel substructure could be a great choice for your next project? In that case, the best thing to do is to contact us in advance of starting the design stage (if that boat hasn’t already sailed), as we need six weeks’ lead time.

Chances are, if we understand what you’re looking to deliver on the project, we can help with some budget advice from the very beginning – to help manage your expectations.

If you’re undecided on which method of below-ground construction to use, ensure you consider the time it will take to install your substructure on-site, the accuracy/tolerances required, and the level of waterproofing you need – along with which option best suits your intended usage.

These are all key factors to consider when choosing the right underground storage method for you.


Thanks for reading, and I hope this blog post has helped to shed some light on the various potential uses for underground storage with prefabricated steel.

Need to know more about whether a prefabricated steel substructure might be the right choice for your project?

Feel free to leave a comment below – or get in touch with me directly. I’ll be happy to help!