How Thick can you Pour Self-Levelling Compound?

How Thick Can you Pour Self-Levelling Compound?

Normally self-levelling compound is poured as a thin 5mm layer to smooth the floor ready for the finished floor covering. HOWEVER

You can comfortably pour 90% of all self-levelling compounds up to around 12mm if you have a very uneven subfloor. The main idea of self-levelling compounds is not to get the floor perfectly level, but more to get rid of any unevenness and ready for a finished floor covering.

Trowelling Self Levelling Compound
Applying Self-Levelling Compound

If you need to start pouring your self-levelling compound any deeper than 12mm over a large area. You might need to consider doing it in two separate pours at 12mm. One to build up the level, and one finishing pour. This is great if you are a beginner as it in effect gives you a practice run. Always check the manufacturer’s DATA SHEET for your specific type of self-levelling compound.

You can increase the depth you can pour self-levelling compound up to 30mm in a single pour, by adding Coarse Aggregate (Gravel) to the mix. You can normally buy Coarse Aggregate (Gravel) in bags from your local builder’s merchants.

I am assuming you are working on the ground floor, if you are looking to do a deep pour of self-levelling compound. When you are performing a deep pour, you soon end up using lots of self levelling compound, which can get expensive.

I tend to use the self-levelling compound below, which you mix with water, as they are often cheaper and can be used at greater depths.

40mm Deep
Ultraplan Renovation Levelling Compound 25kg
£28.99 (£1.16 / kg)


Can be used up to 40mm deep in a single application


Fibre Reinforced so can be applied at greater thicknesses, than conventional self-levelling compounds


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03/15/2024 09:24 am GMT

If you want to know how much self-levelling compound you will need. I have made another article showing you how to work it out. Simply change the floor area and coverage to suit your application. How Much Self-Levelling Compound do you Need?

The self-levelling compound max depth is between 30mm-40mm depending on the manufacturer. If you need to level the floor any more than 30mm or 40mm, I would seriously consider getting a professional to install a concrete floor screed.

Check Out these manufacturers’ Data Sheets to give you more information on the depth you can pour self-levelling compound.

What is self-levelling compound?

Self-levelling compound is also known as a floor screed or floor levelling mix. It is a thin layer of a cement-based mixture that is applied to subfloors in order to level out any bumps.

The mix is applied in a thin layer to subfloors such as concrete and floorboards, you use it before laying another floor, such as tile, above it.

It is called a self-levelling compound as it, in theory, self-levels. What this means is that you don’t have to worry about getting the mix perfectly level. It should flow across the floor, and correct any errors.

While this does generally work, there are limits. It doesn’t flow like water so will not perfectly level over a large area and may require a bit of help from you.

Why use a self-levelling compound?

You use a self-levelling compound to turn a bumpy, uneven subfloor into a perfectly smooth surface. This is great when you are fitting a solid floor such as tile or wood.

Your floor wont be able to hide the bumps and just sit on them when you fit a rigid floor. Tiles will crack and break and a wood floor will bounce and move. Whereas a flooring-like carpet will happily sit on an uneven base.

Sam Wood

Wood by name, wood by nature. I am a fully qualified, time-served, award-winning joiner with an NVQ Level 3 in Carpentry and Joinery as well as an HNC in Construction. Beyond my joinery qualifications, I have also earned a degree in building surveying. I believe these qualifications make me perfectly positioned to provide expert advice on many different areas of DIY as well as share all of the tips I have picked up in over a decade working on building sites!

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