Depending on the environment in which you have poured your liquid screed you may find yourself needing to sand your floors before you can continue with your project. After liquid screed is poured, often a weak, thin layer of laitance will be left sitting on top which will have to be removed within a week to ten days after pouring.
What is Laitance?
Laitance consists of cement and small aggregate particles that rise to the surface when too much moisture has been added to the mix. This may be as a result of inconsistent quantities in the initial mix or as a result of rain damage. Both of these factors will result in poor curing and increase the formation of laitance. This thin layer, although seemingly harmless, is one of the biggest causes of failure in liquid screed floor installation. Whilst initially it may appear that this layer isn’t an issue, as traffic increases on the surface and temperatures fluctuate throughout the year you will begin to notice it will crack and separate, ruining the finish of the screed and any installed flooring.
When Should the Sanding Take Place?
The sanding of the surface should begin a week to ten days after the initial application. The lower portion of the liquid screed will still be drying at this point which is why sanding is ideal during this period of time. Not only will sanding expedite the drying process, but it will also ensure that a stable surface forms on which you can place your flooring of choice.
By using a specialised diamond cutting pad, the screed will be sanded down, removing any layers of laitance. Overall the longevity and durability of the floor will be drastically improved and will ensure any further application of flooring whether it be laminate, tiles, vinyl etc. can be easily installed. The removal of laitance is key in achieving a successful liquid screed installation and ensuring you won’t have to spend time and money fixing your subflooring in the future.