Aug. 11, 2025
Put simply, self levelling compound (SLC) is a cement-based mixture, which contains aggregates and additives designed to smooth, and flatten a surface.
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Self-levelling compound can also be referred to as self-levelling cement, floor screed or floor levelling compound. It’s designed to level uneven floors before installing a new floor, whether that’s tiles, carpet, vinyl or wood.
There are two main types of self-levelling compounds; latex-based SLC and water-based SLC. As the names suggest, water-based self levelling compound is mixed with water, and the latex-based self levelling compound is powder with a liquid acrylic polymer.
But how does a self-leveling compound level itself out? Well, unfortunately, it's not as exciting as you may think, water always finds “level”. The concrete has a low enough viscosity it still allows water to do its thing, but thick enough to harden into a solid surface.
Floor preparation is key to ensure a successful finish. Sweeping and hoovering the floor thoroughly so the surface is clean and free of debris is the first step. Any loose material left on the surface could comprise the final finish. If you spot any cracks or holes in the floor, these should be filled in beforehand. The Ardex P 10 SR Rapid Hardening Crack Repair Resin Kit is great for helping fill those non structural cracks, it’s easy to use and no mixing equipment is required.
Applying primer will help to ensure the SLC adheres to the surface. Primer can also aid in the flow of the leveller and help with its "self-levelling" properties as a primer can slow the absorption of the moisture from the leveller into the screed. When you purchase a self-leveling compound, there may be a suitable primer mentioned in the instructions and how to apply the primer to the subfloor. If not, our team is always happy to help point you in the right direction to find the perfect.
One of the most popular primers is the Mapei Eco Prim Grip Plus, it’s ready-to-use so no mixing involved, and suitable for both internal and external floors and walls.
After the primer has dried, you’ll need to install an edge framework around the perimeter. This helps to guide and contain the SLC to the specific area.
We’d always recommend following the manufacturer's instructions for the best results. However, typically the process is as follows:
Before you start it’s best to check you have all the correct self levelling tools for the job. Following the manufacturer's instructions, add the SLC and water/latex (dependent on the type of self levelling compound you have chosen). Ensure you mix thoroughly, removing all lumps and it's as smooth as possible. We highly recommend using a paddle mixer for the best results.
Read more: Finding The Best Tool Bags & Tool Boxes
Once you are happy with the consistency, pour the leveller onto the surface. Use a flooring trowel to distribute evenly, working the SLC to the very edge of the framework.
Once the self levelling compound has been distributed evenly, use a pin roller to help release trapped air and level the surface.
Check for any low areas, if you do find any, this will need additional mix being added and troweling/pin rolling again. You will also need to check the manufacturer's instructions that the leveller can be used for multiple layers. Also, it is recommended that the use of a primer is used prior to any additional layers being added.
As per the product instructions, allow it to dry, typically you’ll have to wait for 2-24 hours for the self levelling compound to harden. Once the recommended time has passed, and you are happy to do so, remove the framework.
You can now inspect the leveller to ensure you are happy with the results. If you do notice any imperfections/dips, you can apply more leveller as needed.
How Long Does Self Levelling Compound Take To Dry?
Each self levelling compound will have a different recommended drying time, this can span anywhere between 2-24 hours. For best results always follow the manufacturer's instructions.
What Is The Best Latex SLC?
We have a great blog which covers this in detail, read about the best latex self levelling compounds here.
How To Mix Self-Levelling Compounds?
Mixing self-levelling compound differs with each brand & type, for best results follow manufacturer instructions. In general, once all water/latex is added, you add two-thirds of the powder, then the remaining third once fully mixed, as this will aid in a smooth mixture. We wouldn't recommend adding extra water/latex as this can compromise the mixture, especially with latex as this is designed as a 1 bag - 1 bottle mix.
How Thick Should I Lay Self Leveling Compound?
This is dependent on the type and brand of self levelling compound. For example, the Mapei Ultraplan Maxi Ultra Fast Drying Self Levelling Compound is ideal for thicknesses from 3 to 30mm. Whereas the BAL Level Max All In One Leveller is suitable to 2 - 80mm – one of the largest in the market, so it is very dependent, but to find the perfect self levelling compound feel free to contact our team on .
How Long Until You Can Walk On Self Levelling Compound?
Again, this is very dependable on the type and brand of self levelling compound. The Kerakoll Keralevel Eco LR Rapid Repair Mortar can handle foot traffic after 2 hours, whereas the Tilemaster Fine Flow Free Flowing Heavy Duty Self Levelling Compound can handle light foot traffic after 3 hours.
Can You Use A Self Leveling Compound Outside?
Yes, if the self levelling compound is suitable for both internal and external environments, it can be used outside. For example, the Ardex A46 Multi-Purpose Concrete Repair Mortar can be used outside to repair damaged concrete, building ramps and levelling a patio. Here are some popular examples of external self levelling compound options:
Ultra Floor Level It Renovate
BAL External Level Out Fast Set Self Levelling Compound
Kerakoll Levelflex External
Larsen Professional SLC External Self Levelling Compound
Read more: Work In Cold Weather: Can You Tile Outside In Cold Weather?
Can You Put Self Levelling Compound On Tiles?
Yes, you can pour self levelling compound on existing tiles. Ensure the surface is prepped and primed before laying it.
To lay leveller you’ll need a number of different self levelling compound tools, this includes; a mixing bucket, a mixer/mixing paddle, a flooring trowel, and a spiked roller.
Pin rollers are used to level the compound and distribute it evenly across the space. They have adjustable pins which can be raised or lowered to follow an uneven floor. Creating a flat surface.
Spiked rollers are used to remove air bubbles from self levelling compounds. Helping to create a smooth and level surface.
Flooring trowels are used to help distribute self levelling compound over subfloor and are great for directing SLC in the right direction.
Floor preparation tools are used to prep your floor for laying self levelling compound, ensuring you get the best finish possible.
Having a clean mixing tub or bucket is important when mixing self levelling compounds. It ensures debris doesn't get trapped in the mixture, resulting in a bumpy/uneven finish.
At Pro Tiler Tools, we stock a wide range of self-levelling compounds, from several popular brands.
Our range of Ardex Self Levelling Compounds are suitable across a wide range of substrates, including concrete, sand and cement screeds, and existing ceramic and natural stone tiles. The Ardex ARDITEX CL PLUS+ Fibre Reinforced Moisture Tolerant Levelling & Smoothing Compound is a popular choice for DIYers and professionals alike. Suitable for internal use, and under damp proof membranes, it is also walkable in as little as 2 hours.
If you want to learn more, please visit our website High strength cement self-leveling compound.
BAL self-levelling compounds are another popular choice, as they have been formulated to create a smooth, flat and level surface quickly and efficiently. BAL’s fast set range can be walked on only after 30 minutes and tiled on after 45 minutes! Perfect for those working on a time crunch.
Kerakoll self-levelling compounds are ideal for use in heavy-traffic areas; commercial buildings, hospitals, and airports etc. The Kerakoll Levelflex Gel Rapid-Setting Fibre Reinforced Self Levelling Compound is fibre-reinforced with gel-technology, and is walkable after just 90 minutes!
Whether you're a professional tiler or a DIY enthusiast, Larsen self-levelling compounds will help you achieve a perfectly level floor. Larsen Professional SLC FAST Ultra-Rapid Setting Fibre Reinforced Self Levelling Compound is one of their most popular products, suitable for both domestic and commercial properties, and able to withstand light foot traffic in 30 minutes.
Mapei self levelling compounds are known for their quality and performance. One of their most popular SLCs is Mapei Topcem Fast Set Hydraulic Screed Binder, perfect for high traffic areas, fast drying, external and internal use, and suitable for underfloor heating!
Whether you're working on residential renovations or large-scale commercial installations, our Ultra Tile Fix levellers range offers the perfect solution for achieving flawless results. The industry-renowned Ultra Tile Fix Pro Level Two has an advanced formulation, offering rapid setting and exceptional strength, making it the ideal choice for demanding projects. For added reinforcement and flexibility, consider Ultra Tile Fix Pro Level Fibre, specially designed with added fibres for enhanced durability and crack resistance.
If you’re facing a cracked or uneven floor and want a quick, reliable fix, self-leveling concrete might be the perfect solution. Whether you’re renovating a basement, installing a radiant heating system, or simply updating old floors, this fast-setting, easy-to-pour material can save you time and money—while delivering professional-looking results.
Self-leveling concrete can be a fast, cost-effective solution to the problem whenever you need to repair, smooth, or raise a floor.
Self-leveling concrete is a cementitious mixture, much like concrete. But unlike concrete, it flows easier and sets up much faster. The product is mixed with water, pumped or poured into place, and spread evenly with a gauge rake. Once it’s spread out, it continues to flow evenly and levels itself out.
Now that you know what self-leveling concrete is, in the article, we’ll discuss the following:
Depending on the product, it may be smooth and flat within 1-2 hours. In about 6 hours, it may be completely hardened and ready for use, depending on the flooring material being installed on top. Self-leveling concrete can be used as an underlayment for tile, carpet, or other floor coverings.
Now, let’s clarify some things concerning product names. Instead of “concrete,” you might see products called “self-leveling underlayment” or “concrete leveling compound.” This name means the same thing as “self-leveling concrete.”
They’re generally mixtures of Portland cement, polymer plasticizers, and other ingredients. They have the strength of concrete but flow more easily and are set up quickly.
Self-leveling concrete can be poured as thin as a quarter of an inch, just enough to smooth out small imperfections if that’s all you need. But if the concrete floor has low spots and needs to be smoothed even more, it can be poured as thick as an inch and a half without adding aggregate and 5 inches with the addition of aggregate (though make sure you follow all manufacturer’s guidelines).
Self-leveling concrete works especially well with radiant heating installations because it easily flows around the tubing. The thicker floor-leveling compounds that must be troweled to achieve a proper finish can’t do this.
If you find moisture is a problem in the slab, you need to get a professional to handle the moisture remediation. You can also visit the International Concrete Repair Institute (ICRI) for more information on next steps or to find an expert to help.
Let’s say you’re upgrading an old, damaged concrete floor that’s settled or cracked. Or maybe you’re installing a radiant heating system in a floor. Maybe you’re building an addition and must match the floor to the floor in an adjoining room. Maybe you’re finishing a basement where the floor is rough and uneven concrete.
Other concrete toppings applications include warehouse floors, light industrial applications, retail stores, and institutional facilities.
Concrete toppings can also receive pigmented color dyes, stains, saw cuts or mechanical polishing to produce a decorative concrete finished wear surface.
The cost of self-leveling concrete can vary depending on various factors such as the size of the area to be covered, the thickness required, and the brand of the product. On average, a 50-pound bag of self-leveling concrete flooring costs between $30 to $60, and it typically covers an area of about 20 to 30 square feet at a quarter-inch thickness.
Keep in mind that this is only the cost of the material itself. If you’re hiring a professional for the job, labor costs will also factor in. The labor cost usually depends on the complexity of the job and the contractor’s experience and can range from $3 to $5 per square foot.
When compared to traditional concrete leveling methods, self-leveling concrete often proves to be more cost-effective due to its ease of application and reduced labor cost, although the initial material cost might be higher.
Before installing your new floor, there’s an essential consideration you need to address: moisture in the existing concrete floor. All concrete contains moisture, and if the moisture level is too high, it may cause the leveling compound to degrade over time.
So you need to test the slab to ensure the moisture level is not too high.
This isn’t something you can do just by looking at the slab. No matter how the slab looks, moisture deep in the slab can migrate to the surface over time and cause serious problems.
If the moisture level deep in the slab is too high, you need to take steps to remediate it before you can pour your new concrete floor.
RH testing is the basis for the ASTM F standard. This standard governs the processes of obtaining results using in situ probes in concrete slabs. Despite the complex terminology, this test method is actually straightforward and much faster than you would think.
Once the L6 sensors are installed in the slab and equilibrated after the F requirement of 24 hours, there’s no need to move them from location to location and wait for them to equilibrate again.
Repeat readings can be taken without additional equilibration time. And unlike reusable probes, the L6 sensors never need calibration.
While self-leveling concrete is designed to be easy to use, problems can sometimes occur. Here are a few common issues and their solutions:
If the compound doesn’t level as expected, it might be due to incorrect mixing or application. Ensure that you follow the manufacturer’s instructions for mixing and applying the product. Using a gauge rake can help to distribute the product evenly.
This can happen if the compound dries too quickly, which might be due to high temperatures or low humidity. Try to control the working environment as much as possible to avoid rapid drying.
This problem may occur if the old concrete smooth surface wasn’t prepared properly before application. Make sure the surface is clean, free of dust or oil, and primed if necessary before applying the self-leveling concrete.
As mentioned in the original article, high moisture levels can cause problems. Always check the moisture content of the slab before application and take necessary steps if the moisture level is too high.
Remember, when facing difficulties, it’s always beneficial to reach out to a professional or contact the product manufacturer’s customer service. They can provide you with specific advice and guidance based on your situation.
Whenever you need to repair, level, or raise a floor, self-leveling concrete can be a fast, cost-effective solution.
Self-leveling cement can be used as an underlayment for tile, carpet, or other floor coverings.
For a successful self-leveling concrete installation, follow the seven tips in this article.
To ensure that your finished floor does not suffer from a concrete flooring failure, it’s essential to test the concrete subfloor for high moisture levels according to the ASTM F standard. It’s not that hard to do, and you’ve got a great product from Wagner Meters that can help.
The Rapid RH L6 system is the fastest, easiest, most cost-effective system for RH testing concrete slabs in compliance with ASTM F. It will get you accurate results in a fraction of the time versus other methods, and it’s digital, with convenient wireless communication to your smart device.
Learn more about if your concrete is ready for underlayment.
Yes, you can—as long as you properly prepare the surface. Self-leveling concrete requires thorough cleaning, priming, and sealing of any cracks or gaps before pouring. Skipping these steps can lead to poor adhesion and uneven results.
You should avoid using self-leveling concrete if:
Yes. In most cases, self-leveling concrete can be poured over existing slabs. However, the old concrete must be:
Coverage varies by product, but generally, a 50 lb bag covers about 20–30 square feet at ¼-inch thickness. Always consult the manufacturer’s guidelines for exact coverage, as mixing ratios and desired thickness can affect how far each bag goes.
Drying times vary by product and environmental conditions. In many cases, the surface is walkable within 2–4 hours, and you can install most floor coverings after 24 hours. Check your specific product’s instructions for exact curing times.
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