Self levelling concrete is widely used to correct uneven floors and prepare surfaces before installing tiles, wood, or vinyl. When installed correctly it creates a smooth, level base with minimal effort. However, mistakes during preparation or installation can quickly lead to cracking, poor adhesion, or weak floors.
Across London and the South East, many flooring issues occur because self levelling compound is used incorrectly or applied in conditions it was not designed for.
Understanding the most common mistakes can help prevent costly repairs later.
Poor subfloor preparation
One of the biggest causes of failure is poor preparation of the base. Self levelling compound needs a clean, stable surface to bond properly.
Dust, oil, paint residue, or loose concrete can prevent adhesion and cause the levelling layer to separate from the floor.
Before applying any levelling compound, the surface should be cleaned thoroughly and primed where required.
Using self levelling for large height differences
Self levelling concrete is designed for thin applications, usually only a few millimetres thick. Attempting to correct large floor level differences using self levelling compound often leads to cracking and weak spots.
Where significant depth is required, traditional screed or liquid screed is normally the correct solution. Our guide on self levelling compound vs screed explains the difference and when each should be used.
Adding too much water
Another common mistake is adding excess water during mixing. While this may make the compound easier to spread, it weakens the material and increases shrinkage as it dries.
The result can be a soft surface, cracking, or uneven drying across the floor.
Following the correct mixing ratio is essential for a strong and durable finish.
Applying levelling compound too thick
Self levelling products have recommended thickness limits. Applying the material too thick can cause slow drying, internal weakness, or surface cracking.
If the floor requires substantial build up, a screed system should normally be installed first before applying a thin levelling layer.
Ignoring moisture in the subfloor
Moisture problems are common in ground floor slabs and older properties. If the base contains excessive moisture, the levelling compound may not cure properly.
This can lead to powdery surfaces, debonding, or damage to the final floor covering.
Proper moisture testing and damp proof protection are essential before installation.
Rushing the drying process
Even fast drying levelling compounds require time to cure properly. Installing tiles or flooring too early can trap moisture and weaken the bond between layers.
Allowing sufficient drying time helps ensure the surface remains stable and durable.
Why choose LMA Floorscreeding
At LMA Floorscreeding, we have over 15 years of experience installing traditional screed, liquid screed, and self levelling concrete across London, the South East, and wider UK regions.
Our work is built around clear communication, united effort, quality workmanship, and trust. We aim to deliver smooth, level floors that perform reliably for years.
Customers choose LMA because we provide fast, tidy installation, honest advice, and solutions tailored to each project. Our systems also perform exceptionally well with underfloor heating.
If you are planning a flooring project in London or the South East and want reliable results, the LMA Floorscreeding team can help.
We provide expert guidance, practical solutions, and clear quotes so you know exactly what to expect from the start.