Are you curious about using a prefabricated steel substructure for your next project?

As a specialist subcontractor, one of the biggest questions I get asked on a regular basis (after things like installation times, and how much they typically cost to build) is regarding the logistics once a substructure is ready to install.

More specifically, how you attach or fix into the sides of base of a prefabricated steel substructure.

Some people are concerned about whether it’s wildly different from the way they’d install a below-ground substructure constructed using more traditional methods (in situ or precast concrete).

However, I can assure you there’s nothing to worry about. I’m going to tell you all you need to know about this aspect of prefabricated steel substructures, below.

How do you fix into the sides or base?

As you probably know, when you build a substructure traditionally out of in situ concrete, and say, you require brackets or additional material to the sides or base, you would tend to drill and fix it.

If it has been constructed using the correct material, it won’t leak – at least, not until after the amount of years on your guarantee has passed by.

However, with a prefabricated steel substructure, the waterproofing comes from the steel material itself. If you were to drill a hole into the steel, and the water table rises to that level, there would be an issue of water penetrating your substructure.

Fear not, though – we do things differently using this method of below-ground construction.

If you require additional material to the sides or base or a prefabricated steel substructure, we fix our factory bolts, unistrut or captive nuts into position for you.

So, when you need to fix or attach something to the sides, it’s already been coordinated, and these will be in place before leaving the factory.

TIP: Find out the other ways prefabricated steel compares to in situ concrete, by reading my recent blog on the subject.

Advice from a specialist subcontractor

If you’re worried about how to fix into a prefabricated steel substructure, don’t be.

What would usually happen is that you specify any additional materials or fittings you need beforehand (ideally you’d tell us the level of detail required to do this), and we would fix everything you need into place before your substructure leaves the factory.

We would then leave your substructure with these fixings in position for the subcontractor who is fixing the machinery (for example) into the substructure to use.

One example of this would be the prefabricated steel substructure we constructed to be used for the conveyor belt at the London Taxi Company. After we installed the substructure, the supplier of the conveyor belt then fixed the belt to our fixings.

Alternatively, if you don’t know the level of detail required when specifying your prefabricated steel substructure, the same outcome could also be achieved by welding the fixings to the side of your substructure (which is also something we would do).


Thanks for reading. As I’m sure you’re probably aware, prefabricated steel substructures are a very innovative method of below-ground construction – in fact, no-one else is really offering these at the moment. (Despite the fact we have for over 35 years!)

That means that people tend to have a lot of questions about things like cost, installation times, and about the logistics – such as how to add extra fixtures or fittings that you might need.

The good news is that factory bolts, unistrut or captive nuts can be fixed into position for you before your substructure even leaves the factory (if you have that information when specifying your order), or welded by our team afterwards.

So, no drilling required – and you won’t have to worry about your substructure leaking!

Got any other questions about prefabricated steel substructures? Just leave me a comment below. I’d be happy to help!