Can self-levelling compound be built up in layers?

All types of self-levelling compound can be built up in layers. I would even recommend it, if you need build up your floor quite significantly (anything above 10-12mm).

If you are using a cement based self-levelling compound that you add water to, you should wait for your first coat to cure properly. Then prep the surface with PVA (diluted with just enough water to help you spread it with a brush or roller) once tacky apply your 2nd coat of self-levelling compound.

If you are using a 2-part latex self-levelling compound that comes with a the tub of latex included. Such as Ardex NA, you can simply apply the 2nd coat directly to the first with no priming required.

Note: Self-levelling compounds are only designed to be applied in a thin coat ideally around 3-6mm, up to possibly 10-12mm. (After this point you will need to start adding some aggregate and you are essentially making a concrete floor. But as always check the manufacturer’s Datasheet, for your specific type of 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.

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.

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