Whether you are creating a concrete floor for your kitchen, or a simple and hard-wearing floor for a warehouse space, knowing how to lay a concrete floor properly will help to make sure you get it right the first time.
Understanding the different concrete floor layers
Part of the process of laying a concrete floor is to build up the concrete floor layers to ensure the surface is level and suits your requirements. The different concrete floor layers you will need to consider include:
A layer of sub-base should be added and compacted to form a level surface for your concrete floor. This will help to stabilise the ground and ensure the concrete floor does not crack. Infilling any areas that have been excavated will bring the concrete floor to the required level for your project.
Damp-proof Membrane (DPM)
A Damp Proof Membrane (DPM) helps to stop any moisture rising through your concrete floor. Each of the concrete floor layers is important, and including a DPM is particularly vital in moisture-prone areas. A layer of sand should be included before the DPM, and layers of the membrane should be overlapped at the edges to ensure the concrete floor cures at the same rate across its entire area.
Insulating your concrete floor slab helps to stop the cold from rising into your building. The most common insulation for concrete floors is a polystyrene insulation board. This is laid on top of the Damp-proof Membrane and sealed together with strong duct tape. It is vital to ensure the insulation layer extends right up to the walls of your structure.
The concrete layer of your floor will need to be deep enough to provide adequate structural integrity. A depth of at least 100mm is advised, but consult a structural engineer for more detailed calculations based on the requirements of your project.
The screed layer is a thinner concrete mix that is used to level the surface of a concrete floor, this can be used to provide the final surface of the floor, or further decorative finishes can be added.
To prepare the site for your concrete floor you will first need to ensure your measurements are as accurate as possible, and that you have all the correct tools for the job. Once you are ready to begin, start by preparing the ground.
If you are laying a concrete floor on soil you will need to compact the ground to create a level and strong base. Compacting the ground prevents movement underneath your concrete floor, which helps to prevent cracking and ensures the longevity of each of the concrete floor layers.
Using high-quality aggregates, you will need to add a base layer of between two and four inches in thickness. This base layer will also need to be compacted to create a stable base for your concrete floor.
Using reinforcing bars in your concrete floor might be necessary if you are building it to withstand significant loads. For example, if the concrete floor needs to support agricultural machinery or a heavy structure. Reinforcing bars, or ‘rebars’ need to be a certain distance apart depending on the size of the bar and the weight the floor needs to support.
A structural engineer will be able to assist with the calculations for the correct reinforcement of your concrete floor. Fibre-reinforced concrete is also a potential option for lighter loads.
Pouring a concrete floor is simple with readymix concrete delivered directly to your site and ready to pour where it is needed. Mixing concrete by hand for a concrete floor would take a long time, and might result in an uneven finish. Pouring the floor in one go, with a uniform mix, will help to create a consistent surface finish and cuts down on our labour time significantly.
Your concrete floor will need a minimum of 48 hours to cure before light foot traffic can be permitted in the area. It is strongly recommended to allow at least five days for curing before walking on the slab, if possible, as this allows it to increase in hardness.