Self-levelling compounds are intended for thin surface corrections rather than deep floor build-ups. Applying the material too thickly can lead to performance problems during curing and later use. This issue is often seen during renovation projects where uneven slabs are being corrected quickly.
Why thickness matters
Most levelling compounds are designed for depths of 2–10mm, with some systems allowing up to 15mm. When installed beyond the recommended thickness, the compound may cure unevenly. The surface may appear firm while the material underneath remains weak, increasing the risk of cracks or separation.
Common problems when it’s too thick
Excess depth can result in:
- Cracking caused by excessive shrinkage
- Weak or powdery material beneath the top layer
- Poor bonding to the concrete base
- Long drying periods before flooring installation
- Reduced durability in busy areas such as kitchens or hallways
These issues are particularly common where preparation or moisture control has not been handled correctly.
Why it happens
Self-levelling compound is sometimes used to solve large height differences in floors. However, it is designed for final smoothing rather than structural levelling. Problems can also occur when priming is skipped or when the base floor is not properly inspected.
What to use instead
For thicker applications, traditional screed or liquid screed systems are generally the correct solution. These materials are designed to handle deeper layers and heavier loads.
Why choose Floor Screeding Surrey?
Floor Screeding Surrey installs screed and levelling systems across Surrey with experienced teams and clear advice.F