Concrete Slab Foundations: Pros And Cons


The foundation of anything is the basis of it, the beginning of the project. This is what comes first and holds the rest of the project up. In this sense, we’re talking about concrete foundations for buildings such as houses. There are three types of concrete slab foundation types – slab-on-ground, suspended slab and precast slab. In today’s blog, our concrete contractors are going to go in depth and explain to you what some of the pros and cons are of concrete slab foundations.


What exactly is a foundation?

As we said above, a foundation is an initial structure that will support the entire project. But it goes a bit deeper than that. The foundation of a building must do at least three things:

  • Support the structure;
  • Keep out groundwater; and
  • Be a barrier to water and soil vapour.

These are the three points to a successful foundation and are key in their design. But with the three types of foundation structures, there also comes a variety of different features that will appeal to different types of people.


1.   Slab-on-ground foundations

This is the most common concrete slab foundation type and can actually be laid in two different ways:

  • The conventional slabs that feature deep holes with beams. These can be insulated beneath the floor panels; and
  • Waffle pod slabs. These sit closer to the surface and through polystyrene foam contain a maze of beams in between. Waffle pod slabs are already insulated beneath the slabs.

Like the other three concrete slab foundation methods, slab-on-ground employs the use of steel mesh as well as concrete slabs to form the foundation.


2.   Suspended slab

As the name may suggest, these slabs are suspended and do not actually have direct contact with the ground below. These are commonly used as foundations for other floors in multi-storey buildings but can also be used to form the foundation for ground floors. Suspended slab foundations will be often constructed off-site and then transported via a truck.


3.   Precast slab

Precast slabs are also manufactured off-site and then transported and placed where they need to be with a crane. These can be constructed with post-tensioned reinforced or standard concrete as well as from autoclaved aerated concrete – which is lightweight and energy efficient concrete that is manufactured to have multiple closed air pockets inside of it.


Pros of concrete slab foundations

  • Thermal properties – Concrete slabs contain very high thermal mass – meaning it is quite good at storing and re-releasing heat. This works especially well in the sense of foundation as it is a good heat regulator for the house. Of course, to take full advantage of the concrete slab’s thermal properties it must be paired with a passively designed house.
  • Long lasting – Concrete is already a naturally long-lasting creation. But, with the correct reinforcement and design, the concrete slabs can last close to forever. They must be placed correctly and compactly to ensure there are no openings that could cause destabilisation. They must not be affected by water too much as this could weaken them.
  • Termites – Concrete slabs can be highly resistant to termites as long as they have the least number of shrinking joints as possible. Any joints and penetrations should be treated – as well as the edge of the slab.


Cons of concrete slab foundations

  • Insulation design flaws – The edges of concrete slabs have trouble letting heat escape in the colder seasons. With this in mind, you should ensure that the insulation should be constructed to account for this.
  • Thermal properties – The great thermal properties do have their downsides. If your evenings are hot, then the heat stored in the slabs will not dissipate, but instead, continue to be stored in the concrete. To combat this, natural ventilation will need to be provided in the design. This is especially the case in the upper levels of multi-storey houses. This should be paid close attention to particularly if you have bedrooms on upper levels as it could affect comfort whilst sleeping in the evenings.
  • Acoustics – Whilst concrete slabs do reduce sounds such as music and loud conversation, there are certain sounds that are known to penetrate the slabs. Higher impact noises such as heels on the floorboards will get through the slabs. If you know this is likely to happen often and that it will bother you, then you should consider extra acoustic insulation.


Do you need concrete contractors in Melbourne?

Prestige Concrete Services offers high-quality concrete contractors in Melbourne. Our concrete contractors are highly professional and skilled in various concrete services. We have experience in residentialcommercial and local government projects.

If you’re in need of some concrete contractors, then please give us a call on 0411 440 157 or fill out the form on our website.