Everything You Need To Know About Self Levelling Compound
27/01/2025What Is Self-Levelling Compound?
Put simply, self levelling compound (SLC) is a cement-based mixture, which contains aggregates and additives designed to smooth, and flatten a surface.
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.
How Does Self Leveling Compound Work?
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.
How To Lay Self Levelling Compound
Subfloor Preparation
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.
Primer
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.
Edge Framework
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.
Application
We’d always recommend following the manufacturer's instructions for the best results. However, typically the process is as follows:
Mixing Self Levelling Compound
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
Start To Pour
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.
Inspect
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.
Drying Process
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.
Self Levelling Compound FAQs
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 3230 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 01604 859800.
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 3000 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:
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.
What Tools Do I Need To Lay Self Leveling Compounds?
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 Levellers
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
Spiked rollers are used to remove air bubbles from self levelling compounds. Helping to create a smooth and level surface.
Flooring Trowels
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
Floor preparation tools are used to prep your floor for laying self levelling compound, ensuring you get the best finish possible.
Mixing Buckets & Tubs
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.
Popular Self Levelling Compounds
At Pro Tiler Tools, we stock a wide range of self-levelling compounds, from several popular brands.
Self Levelling Compound | Walkable In | Internal Or Exterior | Thickness | Coverage | |
Ardex ARDITEX CL PLUS+ Fibre Reinforced Moisture Tolerant Levelling & Smoothing Compound | 2 hours | Internal | Up to 10mm | Approximately 4m² at 3mm Thick Per Unit | |
30 minutes | Internal | 2 - 30mm | Approximately 4m² at 3mm Thick Per Unit | ||
Kerakoll Levelflex Gel Rapid-Setting Fibre Reinforced Self Levelling Compound | 90 minutes | Internal | 2 - 100mm | Approximately 6.5m² at 2mm Thick Per Unit | |
Larsen Professional SLC 3015 FAST Ultra-Rapid Setting Fibre Reinforced Self Levelling Compound | 30 minutes | Internal | Up to 15mm | Approximately 4.5m² at 3mm Thick Per Unit | |
4-6 hours | Internal | 3 - 40mm. | Approximately 6m² at 3mm Thick per Unit |
Ardex Self Levelling Compounds
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.
BAL Self Levelling Compounds
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
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!
Larsen Self Levelling Compounds
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 3015 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
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!
Ultra Tile Self Levelling Compounds
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.
At Pro Tiler Tools, we have everything you need to successfully lay self levelling compound and our team have the expertise to guide you in the right direction as to the best products to suit your needs. To speak with our team, contact us at 01604 859800 or email us at [email protected].