Even though they are probably not as commonplace as suspended wooden floors concrete slabs are routinely used on the ground floors of properties in the United Kingdom. This means there is a pretty good chance that if you are doing any kind of renovation you will end up tiling directly onto concrete.

Within this blog post we will discuss best practice when it comes to tiling porcelain tiles onto concrete to ensure your project goes without a hitch and you end up with the high end finish you are looking for.

Can You Tile Onto Concrete?

The first thing to determine is whether you can actually tile onto concrete and the answer is an unequivocal yes you can. In the majority of cases cured concrete has strength, stability and flat making it a perfect base for anyone looking to lay porcelain tiles.

How do You Prepare a New Concrete Floor for Tiling?

Before we take a more in depth look at tiling onto a concrete slab you there are a couple of things you need to be 100% sure of:

The first is that the floor is actually concrete, some floors with the appearance of concrete could possibly be anhydrite screed which needs to be treated in a different way. You also need to check that the slab is dry enough.

You should never tile onto top freshly laid concrete. It is important that you give the concrete the time it needs to cure, settle and harden to ensure you get the best results. Drying times vary depending on the depth of the concrete but you can use the timings below as a pretty good guide:

Where the concrete has a thickness, up to a depth of 50mm you should allow one drying day per mm

Once the thickness exceeds 50mm allow 2 drying days per mm

This means that if you have a slab that is 75mm thick, you need to wait 100 days before you begin tiling.

If you don’t allow the concrete slab to harden properly the water that’s present in the concrete slab will not be able to evaporate resulting in it settling between the tiles and the concretes surface. This could result in the adhesive weakening over time, which could causes the porcelain tiles to loosen or fracture. If you are unsure on the thickness of your concrete our advice would be to contact whoever it was that installed the slab.

A good way to test relative humidity or moisture content of any floor is by using a digital hygrometer British Standards state that your relative Humidity reading should be 75% or lower, before you start tiling.

As soon as you are certain that your concrete has dried sufficiently you are ready to start your preparation. If necessary your slab has to be free of laitance, sealed, cleaned and levelled.

Laitance is a thin layer of cement dust that forms on the surface of concrete as it dries. If you don’t remove it, the adhesive might not stick properly, which could lead to floor failure over time. There are several ways to get rid of laitance: for large areas, using shot blasting machines is usually the fastest option, while handheld grinders work best for smaller spots.

As soon as you remove the laitance you need to ensure there is no dust or debris on the slab. You can do this by brushing or sweeping it away and then vacuuming the entire floor area. .

The next step is to apply a sealant using a roller or brush. If necessary a second coat can be applied after the first coat is dry to the touch. This second coat should be applied at a 90 degree angle to the initial one.

If it is needed now is the time to apply a self-levelling compound, which will level out any dips or hollows in the slab and provide you with a nice flat surface perfect for tiling on. Make sure you always use a spiked roller to ensure the self leveller is evenly distributed on the floor, and that you prime the self-leveller before you start tiling.

Once you have done all this you are ready to start tiling on your concrete slab. Our recommendation would be to always use high quality products when doing any kind of tiling as it will help guarantee the best results.

How Do You Prepare an Existing Concrete Floor for Tiling?

If you’re tackling a renovation project and already have a concrete slab, the prep and installation process is pretty similar to that for a new slab. However, keep a few things in mind:

Is the slab clean? You’ll need to remove any surface treatments like paint or sealers.
Is the slab dry? Even though an old slab should be fully cured, make sure there are no moisture issues.
Is the slab damaged? Any cracks need to be fixed to prevent future tile failures.
Is the slab level? If not, use a self-levelling compound to smooth out any bumps or dips.
Is the slab hard? Try scratching the surface with a trowel. If it gives way, you’ll need to grind it down to reach a harder layer.

Do I need to use an anti-fracture mat with my concrete slab?

Even though tiles can be laid straight onto concrete our advice would be to use an anti fracture mat especially if:

Underfloor heating is incorporated into your slab
You are tiling a large space
The tiles you are using are a larger size

These mats are used to reduce the possibility of your tiles cracking, by keeping them separate from the concrete base.

Do I need to prime my concrete slab before tiling?

There are two very good reasons why concrete slabs should always be primed before you start tiling.

For a start concrete is very porous material, the purpose of a primer is to seal the surface, making the bond with the tile adhesive much stronger.

The other reason is that concrete surfaces have a tendency to attract dust. Using a primer will reduce and seal dust, ensuring that you have a better surface to tile onto.

Can I start tiling a new concrete floor immediately?

As we’ve mentioned, it’s important to let a new concrete slab cure and dry before you start tiling. If you don’t, the shrinking concrete might cause your tiles to crack or come loose.

That said, there are ‘fast track’ adhesives that let you start tiling much sooner. Feel free to reach out to us for more details. We hope this blog will have given you all the information about tiling onto new and existing concrete floors however if you need any further information our team will be only too happy to help

is precise and useful for anyone who doesn’t have access to an electric tile cutter it can take a long time and cutting through porcelain is definitely hard work.

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