Are you interested in learning more about precast concrete and whether it’s the best choice for your project?

If so, then you may be researching and comparing various methods of below-ground construction such as the likes of precast, in situ and prefabricated steel.

Precast is usually the first off-site solution you’ll come across when looking for an alternative to in situ, and it can be a good option in some scenarios, but it’s not always the best solution – depending on your requirements.

As a subcontractor who specialises in below-ground construction, I’m going to tell you more about precast concrete, and how to assess whether it’s the best option for you, below.

What exactly is precast concrete?

Precast concrete substructures are constructed out of concrete via an off-site facility, removing the need for a significant amount of manual labour on-site. This also prevents as much waste as you’d find with an in situ project.

This method involves constructing concrete moulds, before pouring the concrete into them via a factory environment. The completed precast concrete substructures are then transported to your site.

Pros of precast concrete:

  • It’s quicker than traditional in situ concrete methods
  • It’s possible to design and construct bespoke precast structures
  • It has higher tolerances than in situ poured concrete
  • It leads to less waste on-site

Cons of precast concrete:

  • In order to be economical, the substructure shapes need to be modular and repetitive
  • Joints between panels can fail as many manufacturers don’t warranty the joint
  • The curing process for precast concrete can lead to cracks
  • If the substructure does encounter cracking, it can lead to leaks and panels having to be removed and replaced
  • Large precast concrete substructures can be very difficult to transport and move into position
  • Cranes are required to lift these on-site
  • It can be expensive (£1,500 – £2,500 per sq. metre)

What makes precast the right choice for a project?

Precast concrete is quite a common and popular method of below-ground construction – and it can often be more effective than in situ. However, this approach is best suited to smaller substructure, due to the weight and labour that goes into physically constructing the moulds.

In fact, the smaller your precast concrete substructure, the less of an issue it will be to transport it to your construction site. But you also have to weigh up the benefits with the risks of cracking and leaks – especially if your project is in a high water table area.

If you’re still interested in an off-site approach, but need a below-ground substructure that definitely won’t leak or crack, you could also look at the option of a prefabricated steel substructure.

To get a better idea of how prefabricated steel substructures compare to precast concrete, check out our recent blog.

TIP: If you’re still not sure if precast concrete is the correct approach for your project, I’d recommend seeking advice from a specialist subcontractor or engineer. They should be able to provide you with some free, impartial advice.


I hope this blog has helped to shed some light on the subject of precast as a method of below-ground construction. It may be the most common method of constructing an off-site substructure, but you should keep an open mind until you’ve explored all your options.

Do you have any questions about precast concrete and how it compares to other off-site approaches? If so, feel free to leave me a comment or get in touch with me directly. I’d love to hear from you!