Curious about how a prefabricated steel substructure compares to other below-ground construction methods in terms of cost?

For any project, cost is always going to be a concern.

Depending on your project, you might find prefabricated steel to be more competitive than precast and even in situ concrete – or not.

However, those who use prefabricated steel tend to appreciate the other benefits, too – such as 70 – 80% reduction of time spent on-site, and the quality of the final product.

As a specialist subcontractor, I’m going to explain more about how prefabricated steel substructures measure up to other methods, below.

How competitively priced is prefabricated steel?

When it comes to substructures, prefabricated steel can be quite competitive. However, it all boils down to the size of the substructure you require.

As an example, a substructure that is long and approximately 1.5m wide x 1.5m deep will be more competitive in price than in situ and precast concrete. These substructures are generally used for vehicle or train inspection pits.

If the substructure is small – such as a manhole or localised pipe or cable ducts, in situ concrete will generally be more competitive and therefore it’s more economical to make large batches for a mass market.

As a general rule of thumb, our substructure quotes tend to be very close when compared to in situ concrete. The main reason for this is that we’ll have additional transport costs and logistics costs (such as a crane lift on-site).

We’re also constructing in our factory a permanent shuttered structure, which is left in position once the concrete is poured around it.

Short-term savings

In the short-term, a prefabricated steel substructure can save you costs due to the time you can save using off-site prefabricated steel vs the longer process of using in situ concrete (this can often be just a matter of days – compared to weeks!).

If you’re borrowing, a prefabricated steel substructure can also potentially save money in terms of interest on the loan (due to the substructure being installed much faster).

As the main contractor, if you’re also on-site then you can save site preliminary costs by using the faster method of off-site prefabricated steel for your below-ground substructure.

Long-term savings

In the long-term, there are also considerable savings to be made. For just one example, a product such as Hanson Concrete can offer between 15 and 30 years’ warranty.

We could issue a 10-year warranty, but our product has been proven by an expert in corrosion to last over 100 years.

End-users of substructures may encounter leaks in the 10 – 15 years after a substructure has been installed with Sika or Hanson products. Leaks can create a big issue if a substructure is to be used 24/7 – and it can take a month to repair whilst causing the owner to lose money.

For instance, in the London Taxi Company’s case, a leaking substructure would be a major spanner in the works, as the organisation would have to try and fix the problem whilst still trying to manufacture taxis.

Advice from a specialist subcontractor

If you’re looking to learn more about the cost of a prefabricated steel substructure, check out our blog on the subject – including the factors that affect the overall price you pay.

However – and this is the part where blogs stop being helpful – it can be difficult to get a good idea of overall costs for your project without speaking to us.

The best thing to do is speak to us over the phone or in person, so we can get a better idea of your project, and your requirements – we’d then be able to help you understand the costs involved and give you a better idea of what can affect them.

As a rough guide, we can construct and install substructures from around £800 – £3,000 per square metre. This does not include extras like finishes or fittings – the material you choose for your substructure (mild steel, stainless steel or aluminium) will affect costs, too.

Remember, when it comes to comparing prices for your substructure, an initial quote for prefabricated steel may be more expensive than in situ concrete, but a full comparison measuring timescales, tolerances and watertightness should all be part of the selection process.


I hope this blog has managed to shed some light on how prefabricated steel substructures measure up to more traditional in situ concrete in terms of costs. Sometimes savings in the short-term can be outweighed by long-term costs and risks.

Prefabricated steel substructures can at times be quite competitively priced, but typically it depends on the size of the substructure you need – along with the material and finish you select for the end product.

Do you have any questions about how much a prefabricated steel substructure might cost for your project? Let me know in the comments below – or alternatively, get in touch directly. I’d love to hear from you!