Concrete Slabs for Commercial Buildings
22 January 2023
Lane Barker, Project Manager
A strong, flat, smooth concrete base is a vital part of your commercial building project.
Getting your slab right ensures that you’ll get a lifetime of use out of your structure, so making sure your concrete is suited to the future use of the structure is a key thing to consider.
In this article, Lane takes us through what to consider when planning the concrete slab for your commercial building. 
What You Need to Know About Concrete Slabs
IN BRIEF
- In commercial building projects, the structural engineer uses the soil report and their understanding of what the structure will be used for to guide the slab’s design.
- The function of the building can determine how the slab is designed which could be with or without joints, or by using traditional mesh or fibre-reinforced concrete.
- The MPa (strength) for a commercial building slab is generally 25 to 32. The thickness of the concrete slab is stated in the project specification documents.
- We typically recommend pouring the footings, building the structure, and then laying the slab – this allows better site access during construction.
Getting the Right Slab
If you’re new to the world of slabs, it’s good to know that not all concrete is created equal. Not only does concrete come in different strengths, but there are also different construction methods – for example using fibre-reinforced concrete vs traditional steel mesh – and then there’s a whole range of jointing systems available.
All of these elements can be customised depending on the way you’ll be using your building and the type of plant and equipment you use in your day-to-day business.
Joint Design
For example, a high-volume warehouse that sees hundreds of forklift movements per day across the floor will be subject to different stresses than a production plant where heavy machinery remains permanently in place. This can affect the joint design.
Some construction methods allow for jointless slabs, however most create large slabs in sections with joins that allow for slight shrinkage or movement as the concrete hardens. This is a natural part of the curing process and is factored into the design of the slab.
The Function of the Building
Additionally, the function of the building may change several times over its lifetime, something that is particularly important for commercial property investors to consider. Laying the right slab for the type of future tenant you want can make it easier to lease your building.
For owner builders, if your business eventually outgrows its premises, a multipurpose slab that suits a range of purposes can be more attractive to new owners down the track, but at the same time, you need to ensure you’re not compromising too much and you’re investing in the type of slab that suits your business now.
Concrete Strength Requirements for Commercial Buildings
When it comes to the strength of the slab itself, this is normally specified by the structural engineer. The engineer uses the soil report and their understanding of what the structure will be used for as a guide to designing the slab. For example, a structure with machinery point loads will have different requirements to a warehouse full of simple pallet racking.
Concrete strength is measured in MPa: this typically refers to the compressive strength after 28 days of curing.
What Comes First, the Slab or the Structure?
Our clients often ask “When should I pour the concrete slab for my building?”
Generally, our recommendation is to build the structure first and then pour the concrete afterwards.
Because the slab is not structural to the building, it can be laid down later, giving better access for heavy machinery to move in and out during the construction phase.
The footings form the actual structural component of the foundations, so pouring the footings, then building the structure, and then pouring the slab is the most sensible workflow.
This process creates a more easily accessible site and ensures that the freshly finished slab is not damaged by machinery.
Can Steelcorp Pour My Concrete Slab?
All of the above design factors are worth considering in the early stages of your project. However, because concrete can be such a specialised field, we don’t look after slabs in-house.
Instead, the Steelcorp team can recommend a concreter in our professional network that can give you a great result.
Having worked with many trades throughout Victoria and NSW, we’ve got a shortlist of the best concreters that can provide a strong, long-lasting base for your new structure. Get in touch with us for an introduction.
