Choosing the correct screed thickness is important when preparing a floor for tiling. If the screed layer is too thin, it may lack strength and lead to cracked tiles or grout. If it is too thick, drying times increase and tiling may be delayed. The required depth depends on the screed type, the floor structure and how the room will be used.
Traditional screed thickness
For traditional sand and cement screed, UK construction guidance generally recommends:
- Bonded screed (applied directly to concrete): minimum 25mm
- Unbonded screed (installed over a membrane): minimum 50mm
- Floating screed (over insulation or underfloor heating): minimum 65mm, or 75mm in areas with heavier loads
These depths provide sufficient strength to support tiled floors and prevent movement or cracking.
Liquid screed thickness
Liquid screeds can often be installed thinner while still achieving good strength.
Typical depths include:
- Bonded liquid screed: around 25–30mm
- Floating liquid screed: around 40–50mm
This reduced thickness can be helpful on refurbishment projects where floor height is restricted.
Why screed thickness matters
Tiles are rigid floor finishes, meaning they cannot tolerate movement beneath them. If the screed is weak or too thin, it can flex under load, leading to cracked grout joints or loose tiles. Correct thickness allows the screed to cure properly and distribute loads evenly.
Common mistakes
Common issues that cause problems include using self-levelling compound to create depth, installing screed too thinly to speed up drying, or laying tiles before the screed has cured fully.
Why choose LMA Floor Screeding London?
With over 15 years of experience, LMA Floor Screeding London installs screed systems across London with reliable workmanship and clear advice.