Liquid screed in Reading is a popular choice for modern construction due to its smooth surface, fast application, and high compatibility with underfloor heating. A drawback that often accompanies liquid screed installations, however, is screed laitance. This weak, thin film of tiny particles and cement can form on the surface during drying, and it can cause adhesion problems and reduce the performance of floor coverings.
Understanding how screed laitance is created and taking preventative action is the solution for hard-wearing, long-lasting flooring.
What Causes Screed Laitance?
Screed laitance generally results from more water than there should be present in the liquid screed mixture, which drives the fine particles apart and towards the surface when the screed is drying. The contributing causes are:
- Overmixing or Unsuitable Mixing Technique – Insufficient mixing results in excessive air entrainment and disrupts the screed consistency.
- Excessive Water Content – An excess of water within the mixture reduces the strength of the binder to such an extent that it promotes laitance formation.
- Insufficient Drying Time – If the screed is not left to dry for a long enough period, laitance occurs due to uneven evaporation of water.
- Environmental Conditions – All three of these, high humidity, temperature variation, and low ventilation, are causes of laitance formation.
Why Is Screed Laitance a Problem?
Even though screed laitance is not always evident, it can be very problematic if not addressed. This thin, weak laitance layer will inhibit the adhesion of floor coverings such as tiles, wood, or vinyl, leading to lifting, cracking, or uneven finishes. It can also be a capillary bridge for water, trapping moisture and increasing the potential for mould growth, as well as compromising the long-term stability of the flooring system.
How to Avoid and Remove Screed Laitance
In UK Screeds Ltd., specialists in liquid screed in Reading and across the UK, various ways are applied to avoid and remove screed laitance:
- Correct Mixing of Screed – Applying the correct mix ratio to prevent excessive water from weakening the screed.
- Sufficient Curing Time – Providing sufficient drying before installing any flooring to prevent laitance from developing.
- Surface Preparation – Light sanding, shot blasting or grinding is effective in removing laitance before installing floor coverings.
- Use of a Primer – Special bonding agents can be applied to promote adhesion and seal the surface before flooring is installed.
By following best practices, screed laitance can be managed effectively, offering a high-quality, long-lasting flooring solution for any project.
For more information, contact UK Screeds Ltd.
