What is a levelling compound?
A levelling compound is a liquid, paste or powder-based mortar used to make a substrate perfectly flat before a finishing layer such as tiles, parquet, laminate or vinyl is installed. The compound fills irregularities, settlement dips and minor cracks so that the finish can be laid without humps or hollows.
Types of levelling compound
By binder, the main types are:
- Cement-based compound — for damp areas and heavy loads
- Calcium sulphate (anhydrite) compound — dries faster, not for damp areas
- Resin-based compound — flexible, for wood, old PVC or steel floors
- Rapid-set compound — walkable within hours, for renovation
- Fibre-reinforced compound — extra crack-resistant
Properties
Key data for selection:
- Layer thickness — usually 1 to 30 mm in one operation
- Open time — 15 to 45 minutes to spread
- Walkability — 2 to 24 hours depending on type
- Final strength — 20 to 35 N/mm²
- Shrinkage — low for crack-free results
Application
Levelling follows a fixed sequence:
- Prepare the substrate — clean, dry, dust- and grease-free
- Apply primer — seals pores and stops rapid water loss
- Mix — combine powder with the prescribed amount of water
- Pour — spread with a (notched) trowel or squeegee
- De-aerate with a spiked roller — to remove air bubbles
- Cure and finish — only lay the final covering after full curing
What does it level out?
| Irregularity | Solution |
|---|---|
| Deep hollows | Pre-level with a thicker coat |
| Cracks | Fibre-reinforced variant |
| Damp floor | Cement-bound type |
| Timber substrate | Resin- or fibre-reinforced variant |
Application
Levelling compound is widely used:
- Before tiling — a smooth, flat surface improves adhesive bond
- Before laminate and parquet — prevents creaking and steps
- Under underfloor heating — flat surface for even heat distribution
- In renovation — levels old concrete or screed floors
- Under vinyl and PVC — a tight surface; otherwise every defect shows through
Related terms
- Floor screed
- Anhydrite floor
- Topping
- Binder
- Primer
- Self-levelling compound
Looking for more DIY plans? Check out fredsdiyplans.com.