If you’re planning a construction project, understanding the different types of concrete slabs available can be as foundational as the structure itself. 

Concrete slabs form the bedrock of most buildings, offering durability and a variety of structural benefits – but not all slabs are created equal.

No matter the size or scale of your upcoming project, choosing the wrong type of the slab can be a costly error.

In this article, we’ll delve into the most common types of concrete slabs used in Melbourne, including on-ground, suspended, and precast. Each type serves distinct purposes and comes with its own set of advantages for different construction needs. 

Whether you’re building a new home, adding an extension, or laying the groundwork for a commercial facility, knowing these options will ensure that your foundation supports your structure optimally.

The longevity, safety, and cost-efficiency of your building can all hinge on this foundational decision, so read on to learn everything you need to know.

NEW: Australian Standards for Laying Concrete (Minimum Thickness)

Melbourne’s Most Common Concrete Options

On-Ground Slabs

On-ground slabs, also known as slab-on-grade, are a popular choice for many residential and commercial buildings in Melbourne. 

These slabs are poured directly on the earth after the site has been excavated and prepared with a layer of compacted sand or gravel to enhance drainage. 

This type of slab is ideal for level sites and is known for its cost-effectiveness and quick installation process.


  • Cost-effective: Generally less expensive than other types due to simpler construction processes.
  • Quick installation: Reduces overall construction time, as it does not require complex frameworks or extensive ground preparation beyond levelling and compacting.
  • Energy efficient: Provides excellent thermal mass, helping to regulate indoor temperatures and reduce heating and cooling costs.


Choosing an on-ground slab involves ensuring the site is appropriately prepared to avoid future settlement issues. It’s crucial to perform a thorough soil test to determine the soil type and ensure adequate drainage and compaction before the concrete is poured. 

Suspended Slabs

Suspended slabs are used primarily in multi-story buildings and situations where the ground conditions are not suitable for on-ground slabs. 

These slabs are supported by walls, beams, or columns and are often used for creating floors between levels in a building. 

Suspended slabs provide excellent structural strength and flexibility in design, making them ideal for uneven terrain or areas prone to flooding.


  • Structural strength: Provides robust support for upper floors in multi-story constructions.
  • Versatile design options: Allows for creative architectural designs and effective use of uneven or sloping sites.
  • Protection against environmental factors: Ideal for flood-prone areas as it raises the building’s base above ground level.


Installing a suspended slab typically involves the use of formwork and sometimes, the incorporation of pre-stressed or post-tensioned steel to enhance strength. Coordination with structural engineers and adherence to local building codes are essential for ensuring the slab’s stability and durability. 

Precast Slabs

Precast slabs are manufactured off-site and delivered ready to install, providing a fast, efficient, and precise method of construction. 

These slabs are ideal for projects that require consistent quality and rapid assembly, such as in commercial developments or high-density residential buildings.


  • High-quality control: Manufactured in a controlled environment, which ensures consistent quality and finish.
  • Reduced construction time: Significantly speeds up the construction process as slabs are prepared off-site and simply installed on-site.
  • Less waste: Produces less waste on the construction site, as excess materials are minimised and can be recycled in the factory setting.


When opting for precast slabs, coordination with the manufacturer is key to ensure that the slabs meet the specific requirements of your project. Detailed planning for transport and installation is also crucial, as these slabs require careful handling to prevent damage.

Navigating Your Concrete Slab Choices

Soil Type and Quality

The type of soil on your construction site plays a pivotal role in determining the most suitable slab. Melbourne’s diverse geography can present varying soil types, each with unique properties that influence the choice of slab. 

Sandy soils, for instance, offer good drainage and are typically paired with on-ground slabs, whereas clay-rich soils may necessitate the use of suspended slabs to counteract soil movement and potential settling issues.

Proper soil testing is crucial to accurately assess the soil type and its bearing capacity. Understanding these factors helps in selecting a slab that not only supports the structure effectively but also minimises the risk of future foundation problems. 

Environmental Considerations

Environmental factors such as climate and potential flood risks are critical.

The city’s variable weather patterns, including its propensity for both drought and heavy rain, require thoughtful consideration of slab types to mitigate potential environmental impacts.

For areas prone to flooding, elevated or suspended slabs may offer a more resilient solution, protecting the structure from water damage.

In addition to flooding, consideration of thermal efficiency is important. 

On-ground slabs, especially those with polished concrete finishes, can offer excellent thermal mass, absorbing heat during the day and releasing it at night, which can be particularly beneficial in Melbourne’s fluctuating temperatures. 

Concept Concrete Tip: Choosing a slab with good thermal properties can significantly enhance the energy efficiency of a building, contributing to a more sustainable and cost-effective structure.


Budget Constraints

Budget is invariably a decisive factor. Each slab type comes with its own cost implications, from the initial outlay for materials and installation to long-term maintenance costs. 

On-ground slabs typically represent the most cost-effective option, particularly suitable for projects with tighter budgets. 

The long-term savings from potentially lower maintenance and energy costs with options like precast or suspended slabs might justify the initial higher investment for some projects.

It’s important to evaluate both the upfront and ongoing costs associated with each type of slab in relation to the overall budget and financial goals of the project. 

Future Usage and Load Requirements

The intended use of the building significantly influences the choice. Structures that anticipate heavy loads, such as industrial buildings or multi-story residential complexes, may require the robustness of suspended slabs. 

These slabs are designed to handle greater loads and offer the flexibility needed for complex architectural designs. For single-story homes or structures with lighter load requirements, a simpler on-ground slab may be entirely adequate. 

It’s essential to align the slab selection with the anticipated future usage to ensure it can adequately support the intended activities and load. 

POPULAR: How to Fix Uneven Concrete Slabs

Concrete Slabs: Final Recap

  • Choose Based on Soil and Environment: The type of soil and environmental conditions like weather and flood risks significantly influence which slab is suitable.
  • Consider the Project’s Future Usage: Align the slab type with the anticipated load requirements and usage of the building.
  • Budget Wisely: Understand the cost implications of each slab type, considering both initial expenses and long-term benefits.

Selecting the right concrete slab is crucial for ensuring the durability, functionality, and cost-effectiveness of your construction project. It’s essential to:

  • Evaluate all factors thoroughly.
  • Align choices with the specific needs of your project.
  • Consult with experts to gain deeper insights and guidance.

Making informed decisions with professional advice can lead to a more successful construction outcome, tailored to both your immediate needs and long-term expectations.

If you’re planning a project in Melbourne and need expert advice on concrete slabs, don’t hesitate to reach out to a member of the Concept Concrete team on 1300 366 343 today.

Take the Next Step with Concept Concrete

At Concept Concrete, we understand the importance of getting your foundation right—the first time. 

Our commitment to excellence ensures that we avoid costly mistakes, making us the go-to experts for your needs.

Why risk the stability of your construction with guesswork? Let Concept Concrete guide you through the complexities of choosing the perfect concrete slab. 

Our team of seasoned experts is ready to provide personalised advice that aligns with your specific construction requirements and to help you make informed decisions that save time and money.

Contact Concept Concrete today at 1300 366 343 or request a fast and FREE quote online today.